The stable Cr isotopic compositions of chondrites and silicate planetary reservoirs

NASA Astrophysics Data System (ADS)

Schoenberg, Ronny; Merdian, Alexandra; Holmden, Chris; Kleinhanns, Ilka C.; Haßler, Kathrin; Wille, Martin; Reitter, Elmar

2016-06-01

The depletion of chromium in Earth's mantle (∼2700 ppm) in comparison to chondrites (∼4400 ppm) indicates significant incorporation of chromium into the core during our planet's metal-silicate differentiation, assuming that there was no significant escape of the moderately volatile element chromium during the accretionary phase of Earth. Stable Cr isotope compositions - expressed as the ‰-difference in 53Cr/52Cr from the terrestrial reference material SRM979 (δ53/52CrSRM979 values) - of planetary silicate reservoirs might thus yield information about the conditions of planetary metal segregation processes when compared to chondrites. The stable Cr isotopic compositions of 7 carbonaceous chondrites, 11 ordinary chondrites, 5 HED achondrites and 2 martian meteorites determined by a double spike MC-ICP-MS method are within uncertainties indistinguishable from each other and from the previously determined δ53/52CrSRM979 value of -0.124 ± 0.101‰ for the igneous silicate Earth. Extensive quality tests support the accuracy of the stable Cr isotope determinations of various meteorites and terrestrial silicates reported here. The uniformity in stable Cr isotope compositions of samples from planetary silicate mantles and undifferentiated meteorites indicates that metal-silicate differentiation of Earth, Mars and the HED parent body did not cause measurable stable Cr isotope fractionation between these two reservoirs. Our results also imply that the accretionary disc, at least in the inner solar system, was homogeneous in its stable Cr isotopic composition and that potential volatility loss of chromium during accretion of the terrestrial planets was not accompanied by measurable stable isotopic fractionation. Small but reproducible variations in δ53/52CrSRM979 values of terrestrial magmatic rocks point to natural stable Cr isotope variations within Earth's silicate reservoirs. Further and more detailed studies are required to investigate whether silicate differentiation processes, such as partial mantle melting and crystal fractionation, can cause stable Cr isotopic fractionation on Earth and other planetary bodies.

Stable isotope analyses of oxygen (18O:17O:16O) and chlorine (37Cl:35Cl) in perchlorate: reference materials, calibrations, methods, and interferences

USGS Publications Warehouse

Böhlke, John Karl; Mroczkowski, Stanley J.; Sturchio, Neil C.; Heraty, Linnea J.; Richman, Kent W.; Sullivan, Donald B.; Griffith, Kris N.; Gu, Baohua; Hatzinger, Paul B.

2017-01-01

RationalePerchlorate (ClO4−) is a common trace constituent of water, soils, and plants; it has both natural and synthetic sources and is subject to biodegradation. The stable isotope ratios of Cl and O provide three independent quantities for ClO4− source attribution and natural attenuation studies: δ37Cl, δ18O, and δ17O (or Δ17O or 17Δ) values. Documented reference materials, calibration schemes, methods, and interferences will improve the reliability of such studies.MethodsThree large batches of KClO4 with contrasting isotopic compositions were synthesized and analyzed against VSMOW-SLAP, atmospheric O2, and international nitrate and chloride reference materials. Three analytical methods were tested for O isotopes: conversion of ClO4− to CO for continuous-flow IRMS (CO-CFIRMS), decomposition to O2 for dual-inlet IRMS (O2-DIIRMS), and decomposition to O2 with molecular-sieve trap (O2-DIIRMS+T). For Cl isotopes, KCl produced by thermal decomposition of KClO4 was reprecipitated as AgCl and converted into CH3Cl for DIIRMS.ResultsKClO4 isotopic reference materials (USGS37, USGS38, USGS39) represent a wide range of Cl and O isotopic compositions, including non-mass-dependent O isotopic variation. Isotopic fractionation and exchange can affect O isotope analyses of ClO4− depending on the decomposition method. Routine analyses can be adjusted for such effects by normalization, using reference materials prepared and analyzed as samples. Analytical errors caused by SO42−, NO3−, ReO42−, and C-bearing contaminants include isotope mixing and fractionation effects on CO and O2, plus direct interference from CO2 in the mass spectrometer. The results highlight the importance of effective purification of ClO4− from environmental samples.ConclusionsKClO4 reference materials are available for testing methods and calibrating isotopic data for ClO4− and other substances with widely varying Cl or O isotopic compositions. Current ClO4−extraction, purification, and analysis techniques provide relative isotope-ratio measurements with uncertainties much smaller than the range of values in environmental ClO4−, permitting isotopic evaluation of environmental ClO4− sources and natural attenuation.

Biscayne aquifer drinking water (USGS45): a new isotopic reference material for δ2H and δ18O measurements of water

USGS Publications Warehouse

Lorenz, Jennifer M.; Tarbox, Lauren V.; Buck, Bryan; Qi, Haiping; Coplen, Tyler B.

2014-01-01

RATIONALE As a result of the scarcity of isotopic reference waters for daily use, a new secondary isotopic reference material for international distribution has been prepared from drinking water collected from the Biscayne aquifer in Ft. Lauderdale, Florida. METHODS This isotopic reference water was filtered, homogenized, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity, and measured by dual-inlet isotope-ratio mass spectrometry. This reference material is available by the case of 144 glass ampoules containing either 4 mL or 5 mL of water in each ampoule. RESULTS The δ2H and δ18O values of this reference material are –10.3 ± 0.4 ‰ and –2.238 ± 0.011 ‰, respectively, relative to VSMOW, on scales normalized such that the δ2H and δ18O values of SLAP reference water are, respectively, –428 and –55.5 ‰. Each uncertainty is an estimated expanded uncertainty (U = 2uc) about the reference value that provides an interval that has about a 95 % probability of encompassing the true value. CONCLUSIONS This isotopic reference material, designated as USGS45, is intended as one of two isotopic reference waters for daily normalization of stable hydrogen and oxygen isotopic analysis of water with an isotope-ratio mass spectrometer or a laser absorption spectrometer. 

A revision in hydrogen isotopic composition of USGS42 and USGS43 human-hair stable isotopic reference materials for forensic science

USGS Publications Warehouse

Coplen, Tyler B.; Qi, Haiping

2016-01-01

The hydrogen isotopic composition (δ2HVSMOW-SLAP) of USGS42 and USGS43 human hair stable isotopic reference materials, normalized to the VSMOW (Vienna-Standard Mean Ocean Water)–SLAP (Standard Light Antarctic Precipitation) scale, was originally determined with a high temperature conversion technique using an elemental analyzer (TC/EA) with a glassy carbon tube and glassy carbon filling and analysis by isotope-ratio mass spectrometer (IRMS). However, the TC/EA IRMS method can produce inaccurate δ2HVSMOW-SLAPresults when analyzing nitrogen-bearing organic substances owing to the formation of hydrogen cyanide (HCN), leading to non-quantitative conversion of a sample into molecular hydrogen (H2) for IRMS analysis. A single-oven, chromium-filled, elemental analyzer (Cr-EA) coupled to an IRMS substantially improves the measurement quality and reliability of hydrogen isotopic analysis of hydrogen- and nitrogen-bearing organic material because hot chromium scavenges all reactive elements except hydrogen. USGS42 and USGS43 human hair isotopic reference materials have been analyzed with the Cr-EA IRMS method, and the δ2HVSMOW-SLAP values of their non-exchangeable hydrogen fractions have been revised:where mUr = 0.001 = ‰. On average, these revised δ2HVSMOW-SLAP values are 5.7 mUr more positive than those previously measured. It is critical that readers pay attention to the δ2HVSMOW-SLAP of isotopic reference materials in publications as they may need to adjust the δ2HVSMOW–SLAP measurement results of human hair in previous publications to ensure all results are on the same isotope-delta scale.

A revision in hydrogen isotopic composition of USGS42 and USGS43 human-hair stable isotopic reference materials for forensic science.

PubMed

Coplen, Tyler B; Qi, Haiping

2016-09-01

The hydrogen isotopic composition (δ(2)HVSMOW-SLAP) of USGS42 and USGS43 human hair stable isotopic reference materials, normalized to the VSMOW (Vienna-Standard Mean Ocean Water)-SLAP (Standard Light Antarctic Precipitation) scale, was originally determined with a high temperature conversion technique using an elemental analyzer (TC/EA) with a glassy carbon tube and glassy carbon filling and analysis by isotope-ratio mass spectrometer (IRMS). However, the TC/EA IRMS method can produce inaccurate δ(2)HVSMOW-SLAP results when analyzing nitrogen-bearing organic substances owing to the formation of hydrogen cyanide (HCN), leading to non-quantitative conversion of a sample into molecular hydrogen (H2) for IRMS analysis. A single-oven, chromium-filled, elemental analyzer (Cr-EA) coupled to an IRMS substantially improves the measurement quality and reliability of hydrogen isotopic analysis of hydrogen- and nitrogen-bearing organic material because hot chromium scavenges all reactive elements except hydrogen. USGS42 and USGS43 human hair isotopic reference materials have been analyzed with the Cr-EA IRMS method, and the δ(2)HVSMOW-SLAP values of their non-exchangeable hydrogen fractions have been revised: [Formula: see text] [Formula: see text] where mUr=0.001=‰. On average, these revised δ(2)HVSMOW-SLAP values are 5.7mUr more positive than those previously measured. It is critical that readers pay attention to the δ(2)HVSMOW-SLAP of isotopic reference materials in publications as they may need to adjust the δ(2)HVSMOW-SLAP measurement results of human hair in previous publications to ensure all results are on the same isotope-delta scale. Published by Elsevier Ireland Ltd.

Calibrating NIST SRM 683 as A New International Reference Standard for Zn Isotopes

NASA Astrophysics Data System (ADS)

Yang, Y.; Zhang, X.; Yu, H.; Huang, F.

2017-12-01

Zinc isotopes have been widely applied in the cosmochemical, geochemical, and environmental studies (Moynier et al. 2017). Obtaining precise Zn isotopic data for inter-laboratory comparison is a prerequisite to these applications. Currently, the JMC3-0749L is the primary reference standard for Zn isotopes (Albarède 2004), but it is not commercially available now. Thus, it is necessary to calibrate a new international primary reference standard for Zn isotopic analysis. Chen et al. (2016) showed that NIST SRM 683 (a pure Zn metal nugget of 140 grams) has a δ66ZnJMC of 0.12‰, which is falling within the range of natural Zn isotopic compositions, and it may a good candidate for the next generation of international reference standard (Chen et al. 2016). In order to further examine whether NIST SRM 683 has a homogeneous Zn isotopic composition, we measured more NIST SRM 683 by double-spike methods using MC-ICPMS (Conway et al. 2013). The metal nuggets of NIST SRM 683 were intensively sampled by micro-drilling. Zinc isotope analyses for two nuggets show that they have δ66Zn of 0.14 ± 0.02‰ (2SD, N = 32) and 0.13 ± 0.02‰ (2SD, N = 33), respectively. These values are similar to those of two Zn metal nuggets (0.11 ± 0.02‰ vs. 0.12 ± 0.02‰) reported previously by Chen et al. (2016). We fully dissolved one nugget, producing pure Zn solution with identical Zn isotopic composition with the drilling samples. All results strongly support that NIST SRM 683 is homogeneous in Zn isotopic compositions which could be an ideal candidate for the next reference for Zn isotopes. Tests on more metal nuggets will be performed in a few months for further confirming the Zn isotope compositions and homogeneity. Reference: Albarède et al., 2004. 'The stable isotope geochemistry of copper and zinc', Reviews in Mineralogy and Geochemistry, 55: 409-27. Chen et al., 2016. 'Zinc Isotopic Compositions of NIST SRM 683 and Whole-Rock Reference Materials', Geostandards and Geoanalytical Research, 40: 417-32. Conway et al., 2013. 'A new method for precise determination of iron, zinc and cadmium stable isotope ratios in seawater by double-spike mass spectrometry', Analytica chimica acta, 793: 44-52. Moynier et al., 2017. 'The isotope geochemistry of zinc and copper', Reviews in Mineralogy and Geochemistry, 82: 543-600.

Calibration strategies for the determination of stable carbon absolute isotope ratios in a glycine candidate reference material by elemental analyser-isotope ratio mass spectrometry.

PubMed

Dunn, Philip J H; Malinovsky, Dmitry; Goenaga-Infante, Heidi

2015-04-01

We report a methodology for the determination of the stable carbon absolute isotope ratio of a glycine candidate reference material with natural carbon isotopic composition using EA-IRMS. For the first time, stable carbon absolute isotope ratios have been reported using continuous flow rather than dual inlet isotope ratio mass spectrometry. Also for the first time, a calibration strategy based on the use of synthetic mixtures gravimetrically prepared from well characterised, highly (13)C-enriched and (13)C-depleted glycines was developed for EA-IRMS calibration and generation of absolute carbon isotope ratio values traceable to the SI through calibration standards of known purity. A second calibration strategy based on converting the more typically determined delta values on the Vienna PeeDee Belemnite (VPDB) scale using literature values for the absolute carbon isotope ratio of VPDB itself was used for comparison. Both calibration approaches provided results consistent with those previously reported for the same natural glycine using MC-ICP-MS; absolute carbon ratios of 10,649 × 10(-6) with an expanded uncertainty (k = 2) of 24 × 10(-6) and 10,646 × 10(-6) with an expanded uncertainty (k = 2) of 88 × 10(-6) were obtained, respectively. The absolute carbon isotope ratio of the VPDB standard was found to be 11,115 × 10(-6) with an expanded uncertainty (k = 2) of 27 × 10(-6), which is in excellent agreement with previously published values.

Tellurium stable isotope fractionation in chondritic meteorites and some terrestrial samples

NASA Astrophysics Data System (ADS)

Fehr, Manuela A.; Hammond, Samantha J.; Parkinson, Ian J.

2018-02-01

New methodologies employing a 125Te-128Te double-spike were developed and applied to obtain high precision mass-dependent tellurium stable isotope data for chondritic meteorites and some terrestrial samples by multiple-collector inductively coupled plasma mass spectrometry. Analyses of standard solutions produce Te stable isotope data with a long-term reproducibility (2SD) of 0.064‰ for δ130/125Te. Carbonaceous and enstatite chondrites display a range in δ130/125Te of 0.9‰ (0.2‰ amu-1) in their Te stable isotope signature, whereas ordinary chondrites present larger Te stable isotope fractionation, in particular for unequilibrated ordinary chondrites, with an overall variation of 6.3‰ for δ130/125Te (1.3‰ amu-1). Tellurium stable isotope variations in ordinary chondrites display no correlation with Te contents or metamorphic grade. The large Te stable isotope fractionation in ordinary chondrites is likely caused by evaporation and condensation processes during metamorphism in the meteorite parent bodies, as has been suggested for other moderately and highly volatile elements displaying similar isotope fractionation. Alternatively, they might represent a nebular signature or could have been produced during chondrule formation. Enstatite chondrites display slightly more negative δ130/125Te compared to carbonaceous chondrites and equilibrated ordinary chondrites. Small differences in the Te stable isotope composition are also present within carbonaceous chondrites and increase in the order CV-CO-CM-CI. These Te isotope variations within carbonaceous chondrites may be due to mixing of components that have distinct Te isotope signatures reflecting Te stable isotope fractionation in the early solar system or on the parent bodies and potentially small so-far unresolvable nucleosynthetic isotope anomalies of up to 0.27‰. The Te stable isotope data of carbonaceous and enstatite chondrites displays a general correlation with the oxidation state and hence might provide a record of the nebular formation environment. The Te stable isotope fractionation of the carbonaceous chondrites CI and CM (and CO potentially) overlap within uncertainty with data for terrestrial Te standard solutions, sediments and ore samples. Assuming the silicate Earth displays similar Te isotope fractionation as the studied terrestrial samples, the data indicate that the late veneer might have been delivered by material similar to CI or CM (or possibly) CO carbonaceous chondrites in terms of Te isotope composition. Nine terrestrial samples display resolvable Te stable isotope fractionation of 0.85 and 0.60‰ for δ130/125Te for sediment and USGS geochemical exploration reference samples, respectively. Tellurium isotopes therefore have the potential to become a new geochemical sedimentary proxy, as well as a proxy for ore-exploration.

LabData database sub-systems for post-processing and quality control of stable isotope and gas chromatography measurements

NASA Astrophysics Data System (ADS)

Suckow, A. O.

2013-12-01

Measurements need post-processing to obtain results that are comparable between laboratories. Raw data may need to be corrected for blank, memory, drift (change of reference values with time), linearity (dependence of reference on signal height) and normalized to international reference materials. Post-processing parameters need to be stored for traceability of results. State of the art stable isotope correction schemes are available based on MS Excel (Geldern and Barth, 2012; Gröning, 2011) or MS Access (Coplen, 1998). These are specialized to stable isotope measurements only, often only to the post-processing of a special run. Embedding of algorithms into a multipurpose database system was missing. This is necessary to combine results of different tracers (3H, 3He, 2H, 18O, CFCs, SF6...) or geochronological tools (Sediment dating e.g. with 210Pb, 137Cs), to relate to attribute data (submitter, batch, project, geographical origin, depth in core, well information etc.) and for further interpretation tools (e.g. lumped parameter modelling). Database sub-systems to the LabData laboratory management system (Suckow and Dumke, 2001) are presented for stable isotopes and for gas chromatographic CFC and SF6 measurements. The sub-system for stable isotopes allows the following post-processing: 1. automated import from measurement software (Isodat, Picarro, LGR), 2. correction for sample-to sample memory, linearity, drift, and renormalization of the raw data. The sub-system for gas chromatography covers: 1. storage of all raw data 2. storage of peak integration parameters 3. correction for blank, efficiency and linearity The user interface allows interactive and graphical control of the post-processing and all corrections by export to and plot in MS Excel and is a valuable tool for quality control. The sub-databases are integrated into LabData, a multi-user client server architecture using MS SQL server as back-end and an MS Access front-end and installed in four laboratories to date. Attribute data storage (unique ID for each subsample, origin, project context etc.) and laboratory management features are included. Export routines to Excel (depth profiles, time series, all possible tracer-versus tracer plots...) and modelling capabilities are add-ons. The source code is public domain and available under the GNU general public licence agreement (GNU-GPL). References Coplen, T.B., 1998. A manual for a laboratory information management system (LIMS) for light stable isotopes. Version 7.0. USGS open file report 98-284. Geldern, R.v., Barth, J.A.C., 2012. Optimization of instrument setup and post-run corrections for oxygen and hydrogen stable isotope measurements of water by isotope ratio infrared spectroscopy (IRIS). Limnology and Oceanography: Methods 10, 1024-1036. Gröning, M., 2011. Improved water δ2H and δ18O calibration and calculation of measurement uncertainty using a simple software tool. Rapid Communications in Mass Spectrometry 25, 2711-2720. Suckow, A., Dumke, I., 2001. A database system for geochemical, isotope hydrological and geochronological laboratories. Radiocarbon 43, 325-337.

Antarctic ice-core water (USGS49) – A new isotopic reference material for δ2H and δ18O measurements of water

USGS Publications Warehouse

Lorenz, Jennifer M.; Qi, Haiping; Coplen, Tyler B.

2017-01-01

As a result of the scarcity of isotopic reference waters for daily use, a new secondary isotopic reference material for international distribution has been prepared from ice-core water from the Amundsen–Scott South Pole Station. This isotopic reference material, designated as USGS49, was filtered, homogenised, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity and measured by dual-inlet isotope-ratio mass spectrometry. The δ2H and δ18O values of USGS49 are −394.7 ± 0.4 and −50.55 ± 0.04 mUr (where mUr = 0.001 = ‰), respectively, relative to VSMOW, on scales normalised such that the δ2H and δ18O values of SLAP reference water are, respectively, −428 and −55.5 mUr. Each uncertainty is an estimated expanded uncertainty (U = 2uc) about the reference value that provides an interval that has about a 95% probability of encompassing the true value. This isotopic reference material is intended as one of two isotopic reference waters for daily normalisation of stable hydrogen and oxygen isotopic analysis of water with an isotope-ratio mass spectrometer or a laser absorption spectrometer. It is available by the case of 144 glass ampoules or as a set of sixteen glass ampoules containing 5 ml of water in each ampoule.

Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).

PubMed

Chew, Gina; Walczyk, Thomas

2013-04-02

Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

Biscayne aquifer drinking water (USGS45): a new isotopic reference material for δ2H and δ18O measurements of water.

PubMed

Lorenz, Jennifer M; Tarbox, Lauren; Buck, Bryan; Qi, Haiping; Coplen, Tyler B

2014-10-15

As a result of the scarcity of isotopic reference waters for daily use, a new secondary isotopic reference material for international distribution has been prepared from drinking water collected from the Biscayne aquifer in Ft. Lauderdale, Florida. This isotopic reference water was filtered, homogenized, loaded into glass ampoules, sealed with a torch, autoclaved to eliminate biological activity, and measured by dual-inlet isotope-ratio mass spectrometry. This reference material is available by the case of 144 glass ampoules containing either 4 mL or 5 mL of water in each ampoule. The δ(2)H and δ(18)O values of this reference material are -10.3 ± 0.4‰ and -2.238 ± 0.011‰, respectively, relative to VSMOW, on scales normalized such that the δ(2)H and δ(18)O values of SLAP reference water are, respectively, -428 and -55.5‰. Each uncertainty is an estimated expanded uncertainty (U = 2uc ) about the reference value that provides an interval that has about a 95% probability of encompassing the true value. This isotopic reference material, designated as USGS45, is intended as one of two isotopic reference waters for daily normalization of stable hydrogen and oxygen isotopic analysis of water with an isotope-ratio mass spectrometer or a laser absorption spectrometer. Published in 2014. This article is a U.S. Government work and is in the public domain in the USA. Published in 2014. This article is a U.S. Government work and is in the public domain in the USA.

Application of non-traditional stable isotopes in analytical ecogeochemistry assessed by MC ICP-MS--A critical review.

PubMed

Irrgeher, Johanna; Prohaska, Thomas

2016-01-01

Analytical ecogeochemistry is an evolving scientific field dedicated to the development of analytical methods and tools and their application to ecological questions. Traditional stable isotopic systems have been widely explored and have undergone continuous development during the last century. The variations of the isotopic composition of light elements (H, O, N, C, and S) have provided the foundation of stable isotope analysis followed by the analysis of traditional geochemical isotope tracers (e.g., Pb, Sr, Nd, Hf). Questions in a considerable diversity of scientific fields have been addressed, many of which can be assigned to the field of ecogeochemistry. Over the past 15 years, other stable isotopes (e.g., Li, Zn, Cu, Cl) have emerged gradually as novel tools for the investigation of scientific topics that arise in ecosystem research and have enabled novel discoveries and explorations. These systems are often referred to as non-traditional isotopes. The small isotopic differences of interest that are increasingly being addressed for a growing number of isotopic systems represent a challenge to the analytical scientist and push the limits of today's instruments constantly. This underlines the importance of a metrologically sound concept of analytical protocols and procedures and a solid foundation of data processing strategies and uncertainty considerations before these small isotopic variations can be interpreted in the context of applied ecosystem research. This review focuses on the development of isotope research in ecogeochemistry, the requirements for successful detection of small isotopic shifts, and highlights the most recent and innovative applications in the field.

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

PubMed

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

2016-04-19

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

Comment on the International Atomic Energy Agency Report on the Advisory Group Meeting on Stable Isotope Reference Samples for Geochemical and Hydrological Investigation, Vienna, Austria, September 19-21, 1983

USGS Publications Warehouse

Coplen, T.B.; Friedman, Irving; O'Neil, J.R.

1984-01-01

According to U.S. Geological Survey records, a report prepared by R. Gonfiantini summarizing the findings and recommendations of the 1983 Advisory Group Meeting on Stable Isotope Reference Samples for Geochemical and Hydrologic Investigations held in Vienna does not accurately represent the consultants ' consensus on three important points. The consultants (1) recommended no value for the C02-H20 oxygen isotope fractionation factor, not the cited value of 1.04115, (2) adopted a value of 1.0309 rather than 1.03086 to relate the PDB and SMOW scales, and (3) adopted a firm 180 value of -2.20% for NBS-19 on the PDB scale rather than agreeing that this would be a tentative value subject to modification when more measurements in selected laboratories are available. (USGS)

Plant family identity distinguishes patterns of carbon and nitrogen stable isotope abundance and nitrogen concentration in mycoheterotrophic plants associated with ectomycorrhizal fungi

PubMed Central

Hynson, Nicole A.; Schiebold, Julienne M.-I.; Gebauer, Gerhard

2016-01-01

Background and Aims Mycoheterotrophy entails plants meeting all or a portion of their carbon (C) demands via symbiotic interactions with root-inhabiting mycorrhizal fungi. Ecophysiological traits of mycoheterotrophs, such as their C stable isotope abundances, strongly correlate with the degree of species’ dependency on fungal C gains relative to C gains via photosynthesis. Less explored is the relationship between plant evolutionary history and mycoheterotrophic plant ecophysiology. We hypothesized that the C and nitrogen (N) stable isotope compositions, and N concentrations of fully and partially mycoheterotrophic species differentiate them from autotrophs, and that plant family identity would be an additional and significant explanatory factor for differences in these traits among species. We focused on mycoheterotrophic species that associate with ectomycorrhizal fungi from plant families Ericaceae and Orchidaceae. Methods Published and unpublished data were compiled on the N concentrations, C and N stable isotope abundances (δ13C and δ15N) of fully (n = 18) and partially (n = 22) mycoheterotrophic species from each plant family as well as corresponding autotrophic reference species (n = 156). These data were used to calculate site-independent C and N stable isotope enrichment factors (ε). Then we tested for differences in N concentration, 13C and 15N enrichment among plant families and trophic strategies. Key Results We found that in addition to differentiating partially and fully mycoheterotrophic species from each other and from autotrophs, C and N stable isotope enrichment also differentiates plant species based on familial identity. Differences in N concentrations clustered at the plant family level rather than the degree of dependency on mycoheterotrophy. Conclusions We posit that differences in stable isotope composition and N concentrations are related to plant family-specific physiological interactions with fungi and their environments. PMID:27451987

New reference materials for nitrogen-isotope-ratio measurements

USGS Publications Warehouse

Böhlke, John Karl; Gwinn, C. J.; Coplen, T. B.

1993-01-01

Three new reference materials were manufactured for calibration of relative stable nitrogen-isotope-ratio measurements: USGS25 (ammonium sulfate) d15N' = -30 per mil; USGS26 (ammonium sulfate) d15N' = +54 per mil; USGS32 (potassium nitrate) d15N' = +180 per mil, where d15N', relative to atmospheric nitrogen, is an approximate value subject to change following interlaboratory comparisons. These materials are isotopically homogeneous in aliquots at least as small as 10 µmol N2 (or about 1-2 mg of salt). The new reference materials greatly extend the range of d15N values of internationally distributed standards, and they allow normalization of d15N measurements over almost the full range of known natural isotope variation on Earth. The methods used to produce these materials may be adapted to produce homogeneous local laboratory standards for routine use.

Quality assurance and quality control in light stable isotope laboratories: A case study of Rio Grande, Texas, water samples

USGS Publications Warehouse

Coplen, T.B.; Qi, H.

2009-01-01

New isotope laboratories can achieve the goal of reporting the same isotopic composition within analytical uncertainty for the same material analysed decades apart by (1) writing their own acceptance testing procedures and putting them into their mass spectrometric or laser-based isotope-ratio equipment procurement contract, (2) requiring a manufacturer to demonstrate acceptable performance using all sample ports provided with the instrumentation, (3) for each medium to be analysed, prepare two local reference materials substantially different in isotopic composition to encompass the range in isotopic composition expected in the laboratory and calibrated them with isotopic reference materials available from the International Atomic Energy Agency (IAEA) or the US National Institute of Standards and Technology (NIST), (4) using the optimum storage containers (for water samples, sealing in glass ampoules that are sterilised after sealing is satisfactory), (5) interspersing among sample unknowns local laboratory isotopic reference materials daily (internationally distributed isotopic reference materials can be ordered at three-year intervals, and can be used for elemental analyser analyses and other analyses that consume less than 1 mg of material) - this process applies to H, C, N, O, and S isotope ratios, (6) calculating isotopic compositions of unknowns by normalising isotopic data to that of local reference materials, which have been calibrated to internationally distributed isotopic reference materials, (7) reporting results on scales normalised to internationally distributed isotopic reference materials (where they are available) and providing to sample submitters the isotopic compositions of internationally distributed isotopic reference materials of the same substance had they been analysed with unknowns, (8) providing an audit trail in the laboratory for analytical results - this trail commonly will be in electronic format and might include a laboratory information management system, (9) making at regular intervals a complete backup of laboratory analytical data (both of samples logged into the laboratory and of mass spectrometric analyses), being sure to store one copy of this backup offsite, and (10) participating in interlaboratory comparison exercises sponsored by the IAEA and other agencies at regular intervals. ?? Taylor & Francis.

Comparing Multiple Criteria for Species Identification in Two Recently Diverged Seabirds

PubMed Central

Militão, Teresa; Gómez-Díaz, Elena; Kaliontzopoulou, Antigoni; González-Solís, Jacob

2014-01-01

Correct species identification is a crucial issue in systematics with key implications for prioritising conservation effort. However, it can be particularly challenging in recently diverged species due to their strong similarity and relatedness. In such cases, species identification requires multiple and integrative approaches. In this study we used multiple criteria, namely plumage colouration, biometric measurements, geometric morphometrics, stable isotopes analysis (SIA) and genetics (mtDNA), to identify the species of 107 bycatch birds from two closely related seabird species, the Balearic (Puffinus mauretanicus) and Yelkouan (P. yelkouan) shearwaters. Biometric measurements, stable isotopes and genetic data produced two stable clusters of bycatch birds matching the two study species, as indicated by reference birds of known origin. Geometric morphometrics was excluded as a species identification criterion since the two clusters were not stable. The combination of plumage colouration, linear biometrics, stable isotope and genetic criteria was crucial to infer the species of 103 of the bycatch specimens. In the present study, particularly SIA emerged as a powerful criterion for species identification, but temporal stability of the isotopic values is critical for this purpose. Indeed, we found some variability in stable isotope values over the years within each species, but species differences explained most of the variance in the isotopic data. Yet this result pinpoints the importance of examining sources of variability in the isotopic data in a case-by-case basis prior to the cross-application of the SIA approach to other species. Our findings illustrate how the integration of several methodological approaches can help to correctly identify individuals from recently diverged species, as each criterion measures different biological phenomena and species divergence is not expressed simultaneously in all biological traits. PMID:25541978

Interlaboratory comparison of reference materials for nitrogen-isotope-ratio measurements

USGS Publications Warehouse

Böhlke, John Karl; Coplen, Tyler B.

1995-01-01

Aliquots of seven different reference materials were distributed for an interlaboratory comparison of stable nitrogen-isotope-ratio measurements. Results from 15 laboratories were compiled and evaluated selectively to yield provisional values of 515N for each material, i, with respect to atmospheric N2 (o1SN,7air). The 515N values reported by the different laboratories are correlated in such a way that some of the major discrepancies may be removed by normalization (/. e., by altering the length of the ô N scale for each laboratory by an amount defined by local measurements of reference materials with extreme values).

Nuclear and isotopic techniques for addressing nutritional problems, with special reference to current applications in developing countries.

PubMed

Iyengar, Venkatesh

2002-03-01

Nuclear and isotopic techniques are valuable tools in human nutritional research studies. Isotopes, both radioactive and nonradioactive, enable detailed evaluations of nutrient intake, body composition, energy expenditure, status of micronutrients, and nutrient bioavailability. In recent times, isotopic methods have been widely used in a number of coordinated research projects and technical cooperation projects of the International Atomic Energy Agency's Nutrition Programme. The doubly labeled water technique combines the use of the stable isotopes oxygen-18 and hydrogen-2 (deuterium) to measure total energy expenditure in free-living human subjects, and to investigate the magnitude and causes of both undernutrition and the emergence of obesity in developing countries. The deuterium dilution technique is a reliable tool to measure breastmilk intake and thereby infant growth and development. In collaboration with the World Health Organization's Growth Monitoring Program, this technique is being used to generate new data on growth standards for children in developing countries. This technique is also used in the measurement of body composition by the estimation of lean body mass and fat mass in individuals. Stable isotopes of iron and zinc have been successfully used to assess the nutritional impact of several nationwide food supplementation-programs conducted on pregnant and lactating women and children in both industrialized and developing countries. Isotopic techniques are especially suitable for monitoring changes in body composition, energy metabolism, and mineral status (with particular reference to osteoporosis) in the elderly. Nuclear methods have also served to develop models for a physiological reference man in Asia in support of radiological health and safety issues, for establishing elemental composition of foods, and for measurement of pollutants in the environment.

Tree-ring stable isotopes record the impact of a foliar fungal pathogen on CO(2) assimilation and growth in Douglas-fir.

PubMed

Saffell, Brandy J; Meinzer, Frederick C; Voelker, Steven L; Shaw, David C; Brooks, J Renée; Lachenbruch, Barbara; McKay, Jennifer

2014-07-01

Swiss needle cast (SNC) is a fungal disease of Douglas-fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible reference species (western hemlock, Tsuga heterophylla) to evaluate their use as proxies for variation in past SNC infection, particularly in relation to potential explanatory climate factors. We sampled trees from an Oregon site where a fungicide trial took place from 1996 to 2000, which enabled the comparison of stable isotope values between trees with and without disease. Carbon stable isotope discrimination (Δ(13)C) of treated Douglas-fir tree-rings was greater than that of untreated Douglas-fir tree-rings during the fungicide treatment period. Both annual growth and tree-ring Δ(13)C increased with treatment such that treated Douglas-fir had values similar to co-occurring western hemlock during the treatment period. There was no difference in the tree-ring oxygen stable isotope ratio between treated and untreated Douglas-fir. Tree-ring Δ(13)C of diseased Douglas-fir was negatively correlated with relative humidity during the two previous summers, consistent with increased leaf colonization by SNC under high humidity conditions that leads to greater disease severity in following years. © 2013 John Wiley & Sons Ltd.

New organic reference materials for hydrogen, carbon, and nitrogen stable isotope-ratio measurements: caffeines, n-alkanes, fatty acid methyl esters, glycines, L-valines, polyethylenes, and oils

USGS Publications Warehouse

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

2016-01-01

An international project developed, quality-tested, and determined isotope−δ values of 19 new organic reference materials (RMs) for hydrogen, carbon, and nitrogen stable isotope-ratio measurements, in addition to analyzing pre-existing RMs NBS 22 (oil), IAEA-CH-7 (polyethylene foil), and IAEA-600 (caffeine). These new RMs enable users to normalize measurements of samples to isotope−δ scales. The RMs span a range of δ2HVSMOW-SLAP values from −210.8 to +397.0 mUr or ‰, for δ13CVPDB-LSVEC from −40.81 to +0.49 mUr and for δ15NAir from −5.21 to +61.53 mUr. Many of the new RMs are amenable to gas and liquid chromatography. The RMs include triads of isotopically contrasting caffeines, C16 n-alkanes, n-C20-fatty acid methyl esters (FAMEs), glycines, and l-valines, together with polyethylene powder and string, one n-C17-FAME, a vacuum oil (NBS 22a) to replace NBS 22 oil, and a 2H-enriched vacuum oil. A total of 11 laboratories from 7 countries used multiple analytical approaches and instrumentation for 2-point isotopic normalization against international primary measurement standards. The use of reference waters in silver tubes allowed direct normalization of δ2H values of organic materials against isotopic reference waters following the principle of identical treatment. Bayesian statistical analysis yielded the mean values reported here. New RMs are numbered from USGS61 through USGS78, in addition to NBS 22a. Because of exchangeable hydrogen, amino acid RMs currently are recommended only for carbon- and nitrogen-isotope measurements. Some amino acids contain 13C and carbon-bound organic 2H-enrichments at different molecular sites to provide RMs for potential site-specific isotopic analysis in future studies.

Historical and contemporary stable isotope tracer approaches to studying mammalian protein metabolism

PubMed Central

2016-01-01

Over a century ago, Frederick Soddy provided the first evidence for the existence of isotopes; elements that occupy the same position in the periodic table are essentially chemically identical but differ in mass due to a different number of neutrons within the atomic nucleus. Allied to the discovery of isotopes was the development of some of the first forms of mass spectrometers, driven forward by the Nobel laureates JJ Thomson and FW Aston, enabling the accurate separation, identification, and quantification of the relative abundance of these isotopes. As a result, within a few years, the number of known isotopes both stable and radioactive had greatly increased and there are now over 300 stable or radioisotopes presently known. Unknown at the time, however, was the potential utility of these isotopes within biological disciplines, it was soon discovered that these stable isotopes, particularly those of carbon (13C), nitrogen (15N), oxygen (18O), and hydrogen (2H) could be chemically introduced into organic compounds, such as fatty acids, amino acids, and sugars, and used to “trace” the metabolic fate of these compounds within biological systems. From this important breakthrough, the age of the isotope tracer was born. Over the following 80 yrs, stable isotopes would become a vital tool in not only the biological sciences, but also areas as diverse as forensics, geology, and art. This progress has been almost exclusively driven through the development of new and innovative mass spectrometry equipment from IRMS to GC‐MS to LC‐MS, which has allowed for the accurate quantitation of isotopic abundance within samples of complex matrices. This historical review details the development of stable isotope tracers as metabolic tools, with particular reference to their use in monitoring protein metabolism, highlighting the unique array of tools that are now available for the investigation of protein metabolism in vivo at a whole body down to a single protein level. Importantly, it will detail how this development has been closely aligned to the technological development within the area of mass spectrometry. Without the dedicated development provided by these mass spectrometrists over the past century, the use of stable isotope tracers within the field of protein metabolism would not be as widely applied as it is today, this relationship will no doubt continue to flourish in the future and stable isotope tracers will maintain their importance as a tool within the biological sciences for many years to come. © 2016 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc. Mass Spec Rev PMID:27182900

Combining stable isotope isotope geochemistry and carbonic anhydrase activity to trace vital effect in carbonate precipitation experiments

NASA Astrophysics Data System (ADS)

Thaler, C.; Ader, M.; Menez, B.; Guyot, F. J.

2013-12-01

Carbonates precipitated by skeleton-forming eukaryotic organisms are often characterized by non-equilibrium isotopic signatures. This specificity is referred to as the "vital effect" and can be used as an isotopic evidence to trace life. Combining stable isotope geochemistry and enzymology (using the enzyme carbonic anhydrase) we aim to demonstrate that prokaryotes are also able to precipitate carbonate with a non-equilibrium d18OCaCO3. Indeed, if in an biomineralization experiment carbonates are precipitated with a vital effect, the addition of carbonic anhydrase should drive the system to isotope equilibrium, And provide a comparison point to estimate the vital effect range. This protocol allowed us to identify a -20‰ vital effect for the d18O of carbonates precipitated by Sporosarcina pasteurii, a bacterial model of carbonatogen metabolisms. This approach is thus a powerfull tool for the understanding of microbe carbonatogen activity and will probably bring new insights into the understanding of bacterial activity in subsurface and during diagenesis.

Stable isotope reactive transport modeling in water-rock interactions during CO2 injection

NASA Astrophysics Data System (ADS)

Hidalgo, Juan J.; Lagneau, Vincent; Agrinier, Pierre

2010-05-01

Stable isotopes can be of great usefulness in the characterization and monitoring of CO2 sequestration sites. Stable isotopes can be used to track the migration of the CO2 plume and identify leakage sources. Moreover, they provide unique information about the chemical reactions that take place on the CO2-water-rock system. However, there is a lack of appropriate tools that help modelers to incorporate stable isotope information into the flow and transport models used in CO2 sequestration problems. In this work, we present a numerical tool for modeling the transport of stable isotopes in groundwater reactive systems. The code is an extension of the groundwater single-phase flow and reactive transport code HYTEC [2]. HYTEC's transport module was modified to include element isotopes as separate species. This way, it is able to track isotope composition of the system by computing the mixing between the background water and the injected solution accounting for the dependency of diffusion on the isotope mass. The chemical module and database have been expanded to included isotopic exchange with minerals and the isotope fractionation associated with chemical reactions and mineral dissolution or precipitation. The performance of the code is illustrated through a series of column synthetic models. The code is also used to model the aqueous phase CO2 injection test carried out at the Lamont-Doherty Earth Observatory site (Palisades, New York, USA) [1]. References [1] N. Assayag, J. Matter, M. Ader, D. Goldberg, and P. Agrinier. Water-rock interactions during a CO2 injection field-test: Implications on host rock dissolution and alteration effects. Chemical Geology, 265(1-2):227-235, July 2009. [2] Jan van der Lee, Laurent De Windt, Vincent Lagneau, and Patrick Goblet. Module-oriented modeling of reactive transport with HYTEC. Computers & Geosciences, 29(3):265-275, April 2003.

Plant family identity distinguishes patterns of carbon and nitrogen stable isotope abundance and nitrogen concentration in mycoheterotrophic plants associated with ectomycorrhizal fungi.

PubMed

Hynson, Nicole A; Schiebold, Julienne M-I; Gebauer, Gerhard

2016-09-01

Mycoheterotrophy entails plants meeting all or a portion of their carbon (C) demands via symbiotic interactions with root-inhabiting mycorrhizal fungi. Ecophysiological traits of mycoheterotrophs, such as their C stable isotope abundances, strongly correlate with the degree of species' dependency on fungal C gains relative to C gains via photosynthesis. Less explored is the relationship between plant evolutionary history and mycoheterotrophic plant ecophysiology. We hypothesized that the C and nitrogen (N) stable isotope compositions, and N concentrations of fully and partially mycoheterotrophic species differentiate them from autotrophs, and that plant family identity would be an additional and significant explanatory factor for differences in these traits among species. We focused on mycoheterotrophic species that associate with ectomycorrhizal fungi from plant families Ericaceae and Orchidaceae. Published and unpublished data were compiled on the N concentrations, C and N stable isotope abundances (δ(13)C and δ(15)N) of fully (n = 18) and partially (n = 22) mycoheterotrophic species from each plant family as well as corresponding autotrophic reference species (n = 156). These data were used to calculate site-independent C and N stable isotope enrichment factors (ε). Then we tested for differences in N concentration, (13)C and (15)N enrichment among plant families and trophic strategies. We found that in addition to differentiating partially and fully mycoheterotrophic species from each other and from autotrophs, C and N stable isotope enrichment also differentiates plant species based on familial identity. Differences in N concentrations clustered at the plant family level rather than the degree of dependency on mycoheterotrophy. We posit that differences in stable isotope composition and N concentrations are related to plant family-specific physiological interactions with fungi and their environments. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Two-Dimensional Stable Isotope Fractionation During Aerobic and Anaerobic Alkane Biodegradation and Implications for the Field

NASA Astrophysics Data System (ADS)

El Morris, Brandon; Suflita, Joseph M.; Richnow, Hans-Hermann

2010-05-01

Quantitatively, n-alkanes comprise a major portion of most crude oils. In petroliferous formations, it may be possible to relate the loss of these compounds to the levels of biodegradation occurring in situ [1]. Moreover, it is important to develop indicators of alkane degradation that may be used to monitor bioremediation of hydrocarbon-impacted environments. Desulfoglaeba alkanexedens and Pseudomonas putida GPo1 were used to determine if carbon and hydrogen stable isotope fractionation could differentiate between n-alkane degradation under anaerobic and aerobic conditions, respectively in the context of the Rayleigh equation model [2]. Bacterial cultures were sacrificed by acidification and headspace samples were analyzed for stable isotope composition using gas chromatography-isotope ratio mass spectrometry. Carbon enrichment factors (bulk) for anaerobic and aerobic biodegradation of hexane were -5.52 ± 0.2‰ and -4.34 ± 0.3‰, respectively. Hydrogen enrichment during hexane degradation was -43.14 ± 6.32‰ under sulfate-reducing conditions, and was too low for quantification during aerobiosis. Collectively, this indicates that the correlation between carbon and hydrogen stable isotope fractionation (may be used to help elucidate in situ microbial processes in oil reservoirs, and during intrinsic as well as engineered remediation efforts. References 1. Asif, M.; Grice, K.; Fazeelat, T., Assessment of petroleum biodegradation using stable hydrogen isotopes of individual saturated hydrocarbon and polycyclic aromatic hydrocarbon distributions in oils from the Upper Indus Basin, Pakistan. Organic Geochemistry 2009, 40, (3), 301-311. 2. Fischer, A.; Herklotz, I.; Herrmann, S.; Thullner, M.; Weelink, S. A. B.; Stams, A., J. M.; Schloemann, M.; Richnow, H.-H.; Vogt, C., Combined carbon and hydrogen isotope fractionation investigations for elucidating benzene biodegradation pathways. Environ. Sci. Technol. 2008, 42, 4356-4363.

The influence of room temperature on Mg isotope measurements by MC-ICP-MS.

PubMed

Zhang, Xing-Chao; Zhang, An-Yu; Zhang, Zhao-Feng; Huang, Fang; Yu, Hui-Min

2018-03-24

We observed that the accuracy and precision of magnesium (Mg) isotope analyses could be affected if the room temperature oscillated during measurements. To achieve high quality Mg isotopic data, it is critical to evaluate how the unstable room temperature affects Mg isotope measurements by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). We measured the Mg isotopes for the reference material DSM-3 using MC-ICP-MS under oscillating room temperatures in spring. For a comparison, we also measured the Mg isotopes under stable room temperatures, which was achieved by the installation of an improved temperature control system in the laboratory. The δ 26 Mg values measured under oscillating room temperatures have a larger deviation (δ 26 Mg from -0.09 to 0.08‰, with average δ 26 Mg = 0.00 ± 0.08 ‰) than those measured under a stable room temperature (δ 26 Mg from -0.03 to 0.03‰, with average δ 26 Mg = 0.00 ± 0.02 ‰) using the same MC-ICP-MS system. The room temperature variation can influence the stability of MC-ICP-MS. Therefore, it is critical to keep the room temperature stable to acquire high precise and accurate isotopic data when using MC-ICP-MS, especially when using the sample-standard bracketing (SSB) correction method. This article is protected by copyright. All rights reserved.

Copper absorption from foods labelled intrinsically and extrinsically with Cu-65 stable isotope.

PubMed

Harvey, L J; Dainty, J R; Beattie, J H; Majsak-Newman, G; Wharf, S G; Reid, M D; Fairweather-Tait, S J

2005-03-01

To determine copper absorption from copper containing foods labelled either intrinsically or extrinsically with a highly enriched Cu-65 stable isotope label. A longitudinal cross-over study. The study was conducted at the Institute of Food Research, Human Nutrition Unit, Norwich, UK. Subjects were recruited locally via advertisements placed around the Norwich Research Park. A total of 10 volunteers (nine female, one male) took part in the study, but not all volunteers completed each of the test meals. A highly enriched Cu-65 stable isotope label was administered to volunteers in the form of a reference dose or in breakfast test meals consisting of red wine, soya beans, mushrooms or sunflower seeds. Faecal monitoring and mass spectrometry techniques were used to estimate the relative quantities of copper absorbed from the different test meals. True copper absorption from the reference dose (54%) was similar to extrinsically labelled red wine (49%) and intrinsically labelled sunflower seeds (52%), but significantly higher than extrinsically labelled mushrooms (35%), intrinsically (29%) and extrinsically (15%) labelled soya beans and extrinsically labelled sunflower seed (32%) test meals. The use of Cu-65 extrinsic labels in copper absorption studies requires validation according to the food being examined; intrinsic and extrinsic labelling produced significantly different results for sunflower seeds.

24-Hour protein, arginine and citrulline metabolism in fed critically ill children – a stable isotope tracer study

PubMed Central

de Betue, Carlijn T.I.; Garcia Casal, Xiomara C.; van Waardenburg, Dick A.; Schexnayder, Stephen M.; Joosten, Koen F.M.; Deutz, Nicolaas E.P.; Engelen, Marielle P.K.J.

2017-01-01

Background & aims The reference method to study protein and arginine metabolism in critically ill children is measuring plasma amino acid appearances with stable isotopes during a short (4–8h) time period and extrapolate results to 24-hour. However, 24-hour measurements may be variable due to critical illness related factors and a circadian rhythm could be present. Since only short duration stable isotope studies in critically ill children have been conducted before, the aim of this study was to investigate 24-hour appearance of specific amino acids representing protein and arginine metabolism, with stable isotope techniques in continuously fed critically ill children. Methods In eight critically ill children, admitted to the pediatric (n=4) or cardiovascular (n=4) intensive care unit, aged 0–10 years, receiving continuous (par)enteral nutrition with protein intake 1.0–3.7 g/kg/day, a 24-hour stable isotope tracer protocol was carried out. L-[ring-2H5]-phenylalanine, L-[3,3-2H2]-tyrosine, L-[5,5,5-2H3]-leucine, L-[guanido-15N2]-arginine and L-[5-13C-3,3,4,4-2H4]-citrulline were infused intravenously and L-[15N]-phenylalanine and L-[1-13C]leucine enterally. Arterial blood was sampled every hour. Results Coefficients of variation, representing intra-individual variability, of the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline were high, on average 14–19% for intravenous tracers and 23–26% for enteral tracers. No evident circadian rhythm was present. The pattern and overall 24-hour level of whole body protein balance differed per individual. Conclusions In continuously fed stable critically ill children, the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline show high variability. This should be kept in mind when performing stable isotope studies in this population. There was no apparent circadian rhythm. PMID:28089618

Fontinalis antipyretica as a bioindicator of environmental conditions in freshwater ecosystem from Sava River watershed and Cerknişko Lake, Slovenia

NASA Astrophysics Data System (ADS)

Kanduč, Tjaša; Mechora, Špela; Stibilj, Vekoslava

2014-05-01

Polluted waters recharging from agriculture water systems into watersheds have influence on water quality and living habitat. Stable isotopes of carbon and nitrogen in combination with other minor and trace elements are often used to trace biogeochemical processes and contamination of water systems. The aim of the study was to assess state of environment with minor and trace elements and stable isotopes of C and N in selected Slovenian streams. Ten locations in Notranjska region, Slovenia, with different land use in the catchment (town, village, agricultural areas, farms, dairy farms), including reference point considered as non-polluted site, were sampled. Samples of water and aquatic moss F. antipyretica in Slovenian fresh waters were taken in all four seasons during years 2010 and 2012, but for stable isotope analyses of C and N only in three seasons during years 2010 and 2011. The water chemistry of investigated locations is dominated by hydrogen carbonate - calcium - magnesium, concentrations of nitrate seasonally range from 2.07 mg/l to 6.4 mg/l and at reference site does not exceed 1.3 mg/l. Total alkalinity of water at investigated locations ranges from 2.9 to 6.02 mM. The pH of investigated water range from 7.2 to 8.5, waters are saturated with oxygen (up to 134%) and conductivity ranges from 295 to 525 mikroS/cm, while at reference site conductivity is up to 180 mikroS/cm. The content of minor and trace elements in F. antipyretica ranged for Ni 4-38 mikrog/g, Zn 17-105 mikrog/g, Pb 2-28 mikrog/g, Cd 220-1953 ng/g, Cu 4-27 mikrog/g, Cr 4-49 mikrog/g, As 1-6 mikrog/g and Se 0.33-3.24 mikrog/g. The most polluted watershed was Pšata stream (agricultural areas, cattle farm) with highest values for Ni, Cr, Pb, Zn and As. The highest content of Se, was found in village (dairy farms) in Žerovniščica stream. The highest values were measured in February and October. Isotopic composition of dissolved inorganic carbon seasonally range from -13.3 to -8.1‰, and indicate waters dominated by degradation of organic matter and dissolution of carbonates. At the reference point average measured isotopic composition of dissolved inorganic carbon value is -2.7‰ which confirmed that this is a non-polluted site. Isotopic composition of carbon of F. antipyretica seasonally ranges from -45 to -32.9‰ and isotopic composition of nitrogen from -0.2‰ to 6.5‰, respectively. In comparison to C3 terrestrial plants F. antipyretica has more negative isotopic composition of carbon value, which is probably related with the difference in CO2 plant fixation and depends on isotopic composition of dissolved inorganic carbon in water, which is primarily controlled by geological composition and soil thickness in the watershed. Higher isotopic composition of nitrogen value found in F. antipyretica is related to agricultural activity in watershed, while at the reference site measured isotopic composition of nitrogen value is -4.1 ‰. From our study it is evident that isotopic composition of carbon and nitrogen is useful tracer of natural and anthropogenic inputs from terrestrial (fertilizing, sewage sludge) to water system.

Progress in the analysis and interpretation of N2O isotopes: Potential and future challenges

NASA Astrophysics Data System (ADS)

Mohn, Joachim; Tuzson, Béla; Zellweger, Christoph; Harris, Eliza; Ibraim, Erkan; Yu, Longfei; Emmenegger, Lukas

2017-04-01

In recent years, research on nitrous oxide (N2O) stable isotopes has significantly advanced, addressing an increasing number of research questions in biogeochemical and atmospheric sciences [1]. An important milestone was the development of quantum cascade laser based spectroscopic devices [2], which are inherently specific for structural isomers (15N14N16O vs. 14N15N16O) and capable to collect real-time data with high temporal resolution, complementary to the well-established isotope-ratio mass-spectrometry (IRMS) method. In combination with automated preconcentration, optical isotope ratio spectroscopy (OIRS) has been applied to disentangle source processes in suburban, rural and pristine environments [e.g. 3, 4]. Within the European Metrology Research Programme (EMRP) ENV52 project "Metrology for high-impact greenhouse gases (HIGHGAS)", the quality of N2O stable isotope analysis by OIRS, the comparability between laboratories, and the traceability to the international isotope ratio scales have been addressed. An inter-laboratory comparison between eleven IRMS and OIRS laboratories, organised within HIGHGAS, indicated limited comparability for 15N site preference, i.e. the difference between 15N abundance in central (N*NO) and end (*NNO) position [5]. In addition, the accuracy of the NH4NO3 decomposition reaction, which provides the link between 15N site preference and the international 15N/14N scale, was found to be limited by non-quantitative NH4NO3 decomposition in combination with substantially different isotope enrichment factors for both nitrogen atoms [6]. Results of the HIGHGAS project indicate that the following research tasks have to be completed to foster research on N2O isotopes: 1) develop improved techniques to link the 15N and 18O abundance and the 15N site preference in N2O to the international stable isotope ratio scales; 2) provide N2O reference materials, pure and diluted in an air matrix, to improve inter-laboratory compatibility. These tasks will be addressed in the upcoming European Metrology Programme for Innovation and Research (EMPIR) project "Metrology for Stable Isotope Reference Standards (SIRS)" starting in June 2017. Acknowledgement Part of this work has been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] S. Toyoda et al., Isotopocule analysis of biologically produced nitrous oxide in various environments, Mass Spectrom. Rev., Doi 10.1002/mas.21459 (2015). [2] J. Mohn et al., Site selective real-time measurements of atmospheric N2O isotopomers by laser spectroscopy, Atmos. Meas. Tech. 5(7), 1601-1609 (2012). [3] B. Wolf et al., First on-line isotopic characterization of N2O above intensively managed grassland, Biogeosci. 12, 2517-2531, (2015). [4] E. Harris et al., Tracking nitrous oxide emission processes at a suburban site with semi-continuous, in-situ measurements of isotopic composition, J. Geophys. Res. Atmos., accepted (2016). [5] J. Mohn et al., Interlaboratory assessment of nitrous oxide isotopomer analysis by isotope ratio mass spectrometry and laser spectroscopy: current status and perspectives, Rapid Commun. Mass Spectrom. 28, 1995-2007 (2014). [6] J. Mohn et al. Reassessment of the NH4NO3 thermal decomposition technique for calibration of the N2O isotopic composition, Rapid Commun. Mass Spectrom. 30, 2487-2496 (2016).

Geographic variation of stable isotopes in African elephant ivory

NASA Astrophysics Data System (ADS)

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

2012-04-01

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

Development of Tandem, Double-Focusing, Electron Impact, Gas Source Mass Spectrometer for Measurement of Rare Double-Substituted Isotoplogues in Geochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, Edward D.

This project culminated in construction and delivery of the world’s first large-radius gas-source isotope ratio mass spectrometer that permits unparalleled analyses of the stable isotopic composition of methane gas. The instrument, referred to as the “Panorama” and installed at UCLA in March 2015, can now be used to determine the relative abundances of rare isotopic species of methane that serve as tracers of temperature of formation and/or subsequent processing of gas. With this technology we can begin to delineate different sources and sinks of methane isotopically in ways not possible until now.

Intercomparison of Lab-Based Soil Water Extraction Methods for Stable Water Isotope Analysis

NASA Astrophysics Data System (ADS)

Pratt, D.; Orlowski, N.; McDonnell, J.

2016-12-01

The effect of pore water extraction technique on resultant isotopic signature is poorly understood. Here we present results of an intercomparison of five common lab-based soil water extraction techniques: high pressure mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and cryogenic extraction. We applied five extraction methods to two physicochemically different standard soil types (silty sand and clayey loam) that were oven-dried and rewetted with water of known isotopic composition at three different gravimetric water contents (8, 20, and 30%). We tested the null hypothisis that all extraction techniques would provide the same isotopic result independent from soil type and water content. Our results showed that the extraction technique had a significant effect on the soil water isotopic composition. Each method exhibited deviations from spiked reference water, with soil type and water content showing a secondary effect. Cryogenic extraction showed the largest deviations from the reference water, whereas mechanical squeezing and centrifugation provided the closest match to the reference water for both soil types. We also compared results for each extraction technique that produced liquid water on both an OA-ICOS and IRMS; differences between them were negligible.

Application of stable isotope tools for evaluating natural and stimulated biodegradation of organic pollutants in field studies.

PubMed

Fischer, Anko; Manefield, Mike; Bombach, Petra

2016-10-01

Stable isotope tools are increasingly applied for in-depth evaluation of biodegradation of organic pollutants at contaminated field sites. They can be divided into three methods i) determination of changes in natural abundance of stable isotopes using compound-specific stable isotope analysis (CSIA), ii) detection of incorporation of stable-isotope label from a stable-isotope labelled target compound into degradation and/or mineralisation products and iii) determination of stable-isotope label incorporation into biomarkers using stable isotope probing (SIP). Stable isotope tools have been applied as key monitoring tools for multiple-line-of-evidence-approaches (MLEA) for sensitive evaluation of pollutant biodegradation. This review highlights the application of CSIA, SIP and MLEA including stable isotope tools for assessing natural and stimulated biodegradation of organic pollutants in field studies dealing with soil and groundwater contaminations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Committee on Diabetes Mellitus Indices of the Japan Society of Clinical Chemistry-recommended reference measurement procedure and reference materials for glycated albumin determination.

PubMed

Takei, Izumi; Hoshino, Tadao; Tominaga, Makoto; Ishibashi, Midori; Kuwa, Katsuhiko; Umemoto, Masao; Tani, Wataru; Okahashi, Mikiko; Yasukawa, Keiko; Kohzuma, Takuji; Sato, Asako

2016-01-01

Glycated albumin is an intermediate glycaemic control marker for which there are several measurement procedures with entirely different reference intervals. We have developed a reference measurement procedure for the purpose of standardizing glycated albumin measurements. The isotope dilution liquid chromatography/tandem mass spectrometry method was developed as a reference measurement procedure for glycated albumin. The stable isotopes of lysine and fructosyl-lysine, which serve as an internal standard, were added to albumin isolated from serum, followed by hydrogenation. After hydrolysis of albumin with hot hydrochloric acid, the liberated lysine and fructosyl-lysine were measured by liquid chromatography/tandem mass spectrometry, and their concentrations were determined from each isotope ratio. The reference materials (JCCRM611) for determining of glycated albumin were prepared from pooled patient blood samples. The isotope dilution-tandem mass spectrometry calibration curve of fructosyl-lysine and lysine showed good linearity (r = 0.999). The inter-assay and intra-assay coefficient of variation values of glycated albumin measurement were 1.2 and 1.4%, respectively. The glycated albumin values of serum in patients with diabetes assessed through the use of this method showed a good relationship with routine measurement procedures (r = 0.997). The relationship of glycated albumin values of the reference material (JCCRM611) between these two methods was the same as the relationship with the patient serum samples. The Committee on Diabetes Mellitus Indices of the Japan Society of Clinical Chemistry recommends the isotope dilution liquid chromatography/tandem mass spectrometry method as a reference measurement procedure, and JCCRM611 as a certified reference material for glycated albumin measurement. In addition, we recommend the traceability system for glycated albumin measurement. © The Author(s) 2015.

Influence of the marine feeding area on the muscle and egg fatty-acid composition of Atlantic salmon Salmo salar spawners estimated from the scale stable isotopes.

PubMed

Torniainen, J; Kainz, M J; Jones, R I; Keinänen, M; Vuorinen, P J; Kiljunen, M

2017-05-01

Fatty acids in muscle tissue and eggs of female Atlantic salmon Salmo salar spawners were analysed to evaluate the dietary quality of their final feeding areas in the Baltic Sea. The final likely feeding area was identified by comparing stable carbon and nitrogen isotope composition of the outermost growth region (final annulus) of scales of returned S. salar with that of reference S. salar caught from different feeding areas. Some overlap of stable-isotope reference values among the three areas, in addition to prespawning fasting, decreased the ability of muscle tri-acylglycerols to discriminate the final likely feeding area and the area's dietary quality. Among three long-chained polyunsaturated fatty acids, docosahexaenoic acid (DHA; 22:6n-3), eicosapentaenoic acid (EPA; 20:5n-3) and arachidonic acid (ARA; 20:4n-6), the proportions of ARA in total lipids of spawning S. salar muscle and eggs showed a significant negative correlation with increasing probability of S. salar having returned from the Baltic Sea main basin (i.e. the Baltic Sea proper). The results suggest that ARA in muscle and eggs is the best dietary indicator for dietary characteristics of final marine feeding area dietary characteristics among S. salar in the Baltic Sea. © 2017 The Fisheries Society of the British Isles.

24-Hour protein, arginine and citrulline metabolism in fed critically ill children - A stable isotope tracer study.

PubMed

de Betue, Carlijn T I; Garcia Casal, Xiomara C; van Waardenburg, Dick A; Schexnayder, Stephen M; Joosten, Koen F M; Deutz, Nicolaas E P; Engelen, Marielle P K J

2017-06-01

The reference method to study protein and arginine metabolism in critically ill children is measuring plasma amino acid appearances with stable isotopes during a short (4-8 h) time period and extrapolate results to 24-h. However, 24-h measurements may be variable due to critical illness related factors and a circadian rhythm could be present. Since only short duration stable isotope studies in critically ill children have been conducted before, the aim of this study was to investigate 24-h appearance of specific amino acids representing protein and arginine metabolism, with stable isotope techniques in continuously fed critically ill children. In eight critically ill children, admitted to the pediatric (n = 4) or cardiovascular (n = 4) intensive care unit, aged 0-10 years, receiving continuous (par)enteral nutrition with protein intake 1.0-3.7 g/kg/day, a 24-h stable isotope tracer protocol was carried out. L-[ring- 2 H 5 ]-phenylalanine, L-[3,3- 2 H 2 ]-tyrosine, L-[5,5,5- 2 H 3 ]-leucine, L-[guanido- 15 N 2 ]-arginine and L-[5- 13 C-3,3,4,4- 2 H 4 ]-citrulline were infused intravenously and L-[ 15 N]-phenylalanine and L-[1- 13 C]leucine enterally. Arterial blood was sampled every hour. Coefficients of variation, representing intra-individual variability, of the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline were high, on average 14-19% for intravenous tracers and 23-26% for enteral tracers. No evident circadian rhythm was present. The pattern and overall 24-h level of whole body protein balance differed per individual. In continuously fed stable critically ill children, the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline show high variability. This should be kept in mind when performing stable isotope studies in this population. There was no apparent circadian rhythm. NCT01511354 on clinicaltrials.gov. Copyright © 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

A new method for stable lead isotope extraction from seawater.

PubMed

Zurbrick, Cheryl M; Gallon, Céline; Flegal, A Russell

2013-10-24

A new technique for stable lead (Pb) isotope extraction from seawater is established using Toyopearl AF-Chelate 650M(®) resin (Tosoh Bioscience LLC). This new method is advantageous because it is semi-automated and relatively fast; in addition it introduces a relatively low blank by minimizing the volume of chemicals used in the extraction. Subsequent analyses by HR ICP-MS have a good relative external precision (2σ) of 3.5‰ for (206)Pb/(207)Pb, while analyses by MC-ICP-MS have a better relative external precision of 0.6‰. However, Pb sample concentrations limit MC-ICP-MS analyses to (206)Pb, (207)Pb, and (208)Pb. The method was validated by processing the common Pb isotope reference material NIST SRM-981 and several GEOTRACES intercalibration samples, followed by analyses by HR ICP-MS, all of which showed good agreement with previously reported values. Copyright © 2013 Elsevier B.V. All rights reserved.

Changes in hydrogen isotope ratios in sequential plumage stages: an implication for the creation of isotope-base maps for tracking migratory birds.

PubMed

Duxbury, J M; Holroyd, G L; Muehlenbachs, K

2003-09-01

Accurate reference maps are important in the use of stable-isotopes to track the movements of migratory birds. Reference maps created by the analysis of samples collected from young at the nest site are more accurate than simply referring to naturally occurring patterns of hydrogen isotope ratios created by precipitation cycles. Ratios of hydrogen isotopes in the nutrients incorporated early in the development of young birds can be derived from endogenous, maternal sources. Base-maps should be created with the analysis of tissue samples from hatchlings after local the isotopic signature of exogenous nutrients is dominant. Migratory species such as Peregrine Falcons are known to use endogenous sources in the creation of their eggs, therefore knowledge of what plumage stage best represents the local hydrogen ratios would assist in the planning of nest visits. We conducted diet manipulation experiments involving Japanese Quail and Peregrine Falcons to determine the plumage stage when hydrogen isotope ratios were indicative of a switch in their food source. The natal down of both the quail and falcons reflected the diet of breeding adult females. The hydrogen isotope ratios of a new food source were dominant in the juvenile down of the young falcons, although a further shift was detected in the final juvenile plumage. The juvenile plumage is grown during weeks 3-4 after hatch on Peregrine Falcons. Nest visits for the purpose of collecting feathers for isotope-base-map creation should be made around 4 weeks after the presumed hatch of the young falcons.

Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry.

PubMed

Frick, Daniel A; Schuessler, Jan A; von Blanckenburg, Friedhelm

2016-09-28

Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ(30)Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ(30)Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g(-1)-range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ simultaneous stable isotope measurement and chemical composition analysis LASS-ICP-MS in combination with MC-ICP-MS is the method of choice. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation into MIS 11 in the U.S. Great Basin Using Trace Elements and Stable Isotopes from two Lehman Caves Stalagmites

NASA Astrophysics Data System (ADS)

Neary, A.; McGee, D.; Tal, I.; Shakun, J. D.

2015-12-01

Marine Isotope Stage 11 (MIS 11) represents a long interglacial period of high temperatures and muted orbital variability that occurred around 424-374 kya, and is referred to as a 'super-interglacial'. MIS 11 is marked by especially pronounced high latitude warming in the Northern Hemisphere from 410-400 ka and thus presents a natural experiment for investigating the response of Great Basin precipitation to high latitude temperatures.MIS 11 is recorded by stalagmites LC3 and BT1 from Lehman Caves in Great Basin National Park, Nevada. LC3 represents 378-413 ka, while BT1 has a bottom age of 410 ka. Ongoing U-Th dating will refine chronologies from these samples. We will present stable isotope (δ13C and δ18O) and trace element (Mg/Ca and Sr/Ca) data from these stalagmites to study changes in precipitation recorded in them. Previous studies have shown a relationship between Mg/Ca, Sr/Ca, δ13C and prior calcite precipitation, and thus infiltration rates, in the cave system (Cross et al., 2015; Steponaitis et al., 2015). Meanwhile, δ18O has been shown to reflect larger scale atmospheric circulation.We will compare the records to previously published trace element and stable isotope data from more recent interglacials (Lachniet et al., 2014; Cross et al., 2015; Steponaitis et al., 2015) to test whether extensive high-latitude warming during MIS 11 was marked by anomalous precipitation patterns in the Great Basin. As they are coeval, we will also test the reproducibility between the stalagmites.References cited:Cross M., et al. (2015) Great Basin hydrology, paleoclimate, and connections with the North Atlantic: A speleothem stable isotope and trace element record from Lehman Caves, NV. Quaternary Science Reviews, in press.Steponaitis E., et al. (2015) Mid-Holocene drying the U.S. Great Basin recorded in Nevada speleothems. Quaternary Science Reviews, in press.Lachniet M. S., et al. (2014) Orbital control of western North America atmospheric circulation and climate over two glacial cycles. Nature Communications 5, 1-8.

Inter-laboratory comparison of elemental analysis and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Part I: delta13C measurements of selected compounds for the development of an isotopic Grob-test.

PubMed

Serra, F; Janeiro, A; Calderone, G; Rojas, J M Moreno; Rhodes, C; Gonthier, L A; Martin, F; Lees, M; Mosandl, A; Sewenig, S; Hener, U; Henriques, B; Ramalho, L; Reniero, F; Teixeira, A J; Guillou, C

2007-03-01

This study was directed towards investigating suitable compounds to be used as stable isotope reference materials for gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) calibration. Several compounds were selected from those used in the 'Grob-test' mixture. Oxygen- and nitrogen-containing substances were added to these compounds to allow the mixture to be used as a possible multi-isotopic calibration tool for 2H/1H, 13C/12C, 15N/14N and 18O/16O ratio determinations. In this paper we present the results of delta13C measurements performed by the consortium of the five laboratories taking part in this inter-calibration exercise. All the compounds were individually assessed for homogeneity, short-term stability and long-term stability by means of EA-IRMS, as required by the bureau communitaire de reference (BCR) Guide for Production of Certified Reference Materials. The results were compared then with the GC-C-IRMS measurements using both polar and non-polar columns, and the final mixture of selected compounds underwent a further certification exercise assessing limits of accuracy and reproducibility under specified GC-C-IRMS conditions. Copyright 2007 John Wiley & Sons, Ltd.

Distinguishing sources of ground water recharge by using δ2H and δ18O

USGS Publications Warehouse

Blasch, Kyle W.; Bryson, Jeannie R.

2007-01-01

Stable isotope values of hydrogen and oxygen from precipitation and ground water samples were compared by using a volumetrically based mixing equation and stable isotope gradient to estimate the season and location of recharge in four basins. Stable isotopes were sampled at 11 precipitation sites of differing elevation during a 2-year period to quantify seasonal stable isotope contributions as a function of elevation. Supplemental stable isotope data collected by the International Atomic Energy Association during a 14-year period were used to reduce annual variability of the mean seasonal stable isotope data. The stable isotope elevation relationships and local precipitation elevation relationships were combined by using a digital elevation model to calculate the total volumetric contribution of water and stable isotope values as a function of elevation within the basins. The results of these precipitation calculations were compared to measured ground water stable isotope values at the major discharge points near the terminus of the basins. Volumetric precipitation contributions to recharge were adjusted to isolate contributing elevations. This procedure provides an improved representation of recharge contributions within the basins over conventional stable isotope methods. Stable isotope values from wells and springs at the terminus of each basin were used to infer the elevations of precipitation important for recharge of the regional ground water flow system. Ancillary climatic, geologic, and stable isotope values were used to further constrain the location where precipitation is entering the ground water flow system.

Optimization of post-run corrections for water stable isotope measurements by laser spectroscopy

NASA Astrophysics Data System (ADS)

van Geldern, Robert; Barth, Johannes A. C.

2013-04-01

Light stable isotope analyses of hydrogen and oxygen of water are used in numerous aquatic studies from various scientific fields. The advantage of using stable isotope ratios is that water molecules serve as ubiquitous and already present natural tracers. Traditionally, the samples were analyzed in the laboratory by isotope ratio mass spectrometry (IRMS). Within recent years these analyses have been revolutionized by the development of new isotope ratio laser spectroscopy (IRIS) systems that are said to be cheaper, more robust and mobile compared to IRMS. Although easier to operate, laser systems also need thorough calibration with international reference materials and raw data need correction for analytical effects. A major issue in systems that use liquid injection via a vaporizer module is the memory effect, i.e. the carry-over from the previous analyzed sample in a sequence. This study presents an optimized and simple post-run correction procedure for liquid water injection developed for a Picarro water analyzer. The Excel(TM) template will rely exclusively on standard features implemented in MS Office without the need to run macros, additional code written in Visual Basic for Applications (VBA) or to use a database-related software such as MS Access or SQL Server. These protocols will maximize precision, accuracy and sample throughput via an efficient memory correction. The number of injections per unknown sample can be reduced to 4 or less. This procedure meets the demands of faster throughput with reduced costs per analysis. Procedures were verified by an international proficiency test and traditional IRMS techniques. The template is available free for scientific use from the corresponding author or the journals web site (van Geldern and Barth, 2012). References van Geldern, R. and Barth, J.A.C. (2012) Limnol. Oceanogr. Methods 10:1024-1036 [doi: 10.4319/lom.2012.10.1024

web-based interactive data processing: application to stable isotope metrology.

PubMed

Verkouteren, R M; Lee, J N

2001-08-01

To address a fundamental need in stable isotope metrology, the National Institute of Standards and Technology (NIST) has established a web-based interactive data-processing system accessible through a common gateway interface (CGI) program on the internet site http://www. nist.gov/widps-co2. This is the first application of a web-based tool that improves the measurement traceability afforded by a series of NIST standard materials. Specifically, this tool promotes the proper usage of isotope reference materials (RMs) and improves the quality of reported data from extensive measurement networks. Through the International Atomic Energy Agency (IAEA), we have defined standard procedures for stable isotope measurement and data-processing, and have determined and applied consistent reference values for selected NIST and IAEA isotope RMs. Measurement data of samples and RMs are entered into specified fields on the web-based form. These data are submitted through the CGI program on a NIST Web server, where appropriate calculations are performed and results returned to the client. Several international laboratories have independently verified the accuracy of the procedures and algorithm for measurements of naturally occurring carbon-13 and oxygen-18 abundances and slightly enriched compositions up to approximately 150% relative to natural abundances. To conserve the use of the NIST RMs, users may determine value assignments for a secondary standard to be used in routine analysis. Users may also wish to validate proprietary algorithms embedded in their laboratory instrumentation, or specify the values of fundamental variables that are usually fixed in reduction algorithms to see the effect on the calculations. The results returned from the web-based tool are limited in quality only by the measurements themselves, and further value may be realized through the normalization function. When combined with stringent measurement protocols, two- to threefold improvements have been realized in the reproducibility of carbon-13 and oxygen-18 determinations across laboratories.

Integration of Stable Isotope and other Mass Spectral Data for Microbial Forensics

NASA Astrophysics Data System (ADS)

Kreuzer-Martin, H. W.; Jarman, K. H.

2008-12-01

The nascent field of microbial forensics requires the development of diverse signatures as indicators of various aspects of the production environment of microorganisms. We have characterized isotopic relationships between Bacillus subtilis ATCC 6051 spores and their growth environment, using as a database the carbon, nitrogen, oxygen and hydrogen stable isotope ratios of a total of 247 separate cultures of spores produced on a total of 32 different culture media. We have analyzed variation within individual samples, between cultures produced in tandem, and between cultures produced in the same medium but at different times in the context of using stable isotope ratios as a signature for sample matching. We have correlated the stable isotope ratios of carbon, nitrogen, oxygen, and hydrogen of growth medium nutrients or water and spores and show examples of how these relationships can be used to exclude nutrient or water samples as possible growth substrates for specific cultures. The power of stable isotope ratio data can be greatly enhanced by combining it with orthogonal datasets that speak to different aspects of an organism's production environment. We developed a Bayesian network that follows the causal relationship from culture medium recipe to spore elemental content as measured by secondary ion mass spectrometry (SIMS), carbon and nitrogen stable isotope ratios, and to the presence of residual agar by electrospray ionization MS (ESI-MS). The network was developed and tested on data from three replicate cultures of B. subtilis ATCC 49760 in broth and agar-containing versions of four different nutrient media. To test the network, data from SIMS analyses of B. subtilis 49760 produced in a different medium, from approximately 200 ESI MS analyses of B. thuringensis ATCC 58890 and B. anthracis Sterne grown in five additional media, and the stable isotope data from the 247 cultures of B. subtilis 6051 spores were used. This network was able to characterize Bacillus spores grown under multiple culture conditions with an error rate of less than 0.07 in characterizing carbon and nitrogen source, addition of metals, and presence of agar, and an error rate of 0.19 in characterizing the culture medium recipe. The integration of multiple analytical techniques allowed us to maximize the amount of information obtained from unknown source microorganisms. The Bayesian network approach allowed us to combine scientific understanding with well established statistical methodologies to characterize a microbe's growth environment without the need for reference signatures. Similar approaches could be applied to data from other scientific disciplines, as well as to other problems of attribution.

Tellurium Stable Isotope Fractionation in Chondritic Meteorites

NASA Astrophysics Data System (ADS)

Fehr, M. A.; Hammond, S. J.; Parkinson, I. J.

2014-09-01

New Te double spike procedures were set up to obtain high-precision accurate Te stable isotope data. Tellurium stable isotope data for 16 chondrite falls are presented, providing evidence for significant Te stable isotope fractionation.

Reconstruction of Late Quaternary Climate in Central Europe - A Comparison of Stable Isotope and Trace Element Variations in Speleothems From Different Cave Systems in Germany.

NASA Astrophysics Data System (ADS)

Nordhoff, P.; Wiegand, B.; Simon, K.; Rosendahl, W.; Hansen, B. T.; Kempe, S.

2003-12-01

Speleothems (stalagmites, stalactites, flowstones) are important archives for Late Quaternary continental climatic and paleo-environmental reconstruction. Speleothems form when calcium carbonate precipitates from solutions seeping into caves hosted e.g. in limestone or dolomite complexes. Information of past climate variability and changes in local environmental conditions can be obtained from signatures of the stable isotopes of oxygen and carbon as well as trace element pattern recorded in speleothems. Reconstruction of paleo-temperature and past environmental conditions from stable isotopes, however, require isotopic equilibrium between the drip water and the precipitating calcium carbonate. Results from Dietzel et al. (1992) and Johnson and Ingram (2001) indicate that the formation of modern travertine and speleothem calcite occurs under isotopic equilibrium. Factors that influence the stable oxygen and carbon isotope composition during speleothem precipitation include e.g. the moisture source and precipitation, photosynthetic pathways, the bedrock proportion, and the drip rate. This often leads to a situation with several variables. However, a specific interpretation is possible when dealing with environments where only one of the factors is dominant, or specific settings are assumed to be invariant, or further proxies like trace element variations help to define the frame conditions during speleothem formation. Concentrations of trace elements (e.g. Sr, Mg) which are co-precipitated with calcite are related to changes in the composition of the solution and strongly depend on the dissolution/precipitation dynamics along drip water flow paths. In a multiproxy approach they are a valuable tool for the interpretation of the recorded stable isotope variations. We present first results from different cave systems located in the Swabian Alps and the Harz Mountains (Germany). Our study includes a high-resolution multiproxy approach, using U/Th-TIMS data, stable oxygen/carbon isotope data, and geochemical compositions of speleothems, covering ages from the Late Pleistocene to the Early Holocene. The results are compared to geochemical data from host rocks, soil zones, cave sediments, drip water compositions, and recent calcium carbonate precipitates. Understanding the response of a cave system to the actual climatic, hydrologic and environmental regimen is a main requirement for the interpretation of "paleo-information" conserved in speleothems in order to lead to a coherent picture of past continental climate dynamics. References: Dietzel M., Usdowski E., and Hoefs J., (1992): Applied Geochemistry 7: 177-184. Johnson, K.R. and Ingram, B.L. (2001): Abstract volume, 4th Internat. Symp. On Applied Isotope Geochemistry, Pacific Groove, USA: 70-72.

Stable isotope composition (δ(13)C and δ(15)N values) of slime molds: placing bacterivorous soil protozoans in the food web context.

PubMed

Tiunov, Alexei V; Semenina, Eugenia E; Aleksandrova, Alina V; Tsurikov, Sergey M; Anichkin, Alexander E; Novozhilov, Yuri K

2015-08-30

Data on the bulk stable isotope composition of soil bacteria and bacterivorous soil animals are required to estimate the nutrient and energy fluxes via bacterial channels within detrital food webs. We measured the isotopic composition of slime molds (Myxogastria, Amoebozoa), a group of soil protozoans forming macroscopic spore-bearing fruiting bodies. An analysis of largely bacterivorous slime molds can provide information on the bulk stable isotope composition of soil bacteria. Fruiting bodies of slime molds were collected in a monsoon tropical forest of Cat Tien National Park, Vietnam, and analyzed by continuous-flow isotope ratio mass spectrometry. Prior to stable isotope analysis, carbonates were removed from a subset of samples by acidification. To estimate the trophic position of slime molds, their δ(13) C and δ(15) N values were compared with those of plant debris, soil, microbial destructors (litter-decomposing, humus-decomposing, and ectomycorrhizal fungi) and members of higher trophic levels (oribatid mites, termites, predatory macroinvertebrates). Eight species of slime molds represented by at least three independent samples were 3-6‰ enriched in (13) C and (15) N relative to plant litter. A small but significant difference in the δ(13) C and δ(15) N values suggests that different species of myxomycetes can differ in feeding behavior. The slime molds were enriched in (15) N compared with litter-decomposing fungi, and depleted in (15) N compared with mycorrhizal or humus-decomposing fungi. Slime mold sporocarps and plasmodia largely overlapped with oribatid mites in the isotopic bi-plot, but were depleted in (15) N compared with predatory invertebrates and humiphagous termites. A comparison with reference groups of soil organisms suggests strong trophic links of slime molds to saprotrophic microorganisms which decompose plant litter, but not to humus-decomposing microorganisms or to mycorrhizal fungi. Under the assumption that slime molds are primarily feeding on bacteria, the isotopic similarity of slime molds and mycophagous soil animals indicates that saprotrophic soil bacteria and fungi are similar in bulk isotopic composition. Copyright © 2015 John Wiley & Sons, Ltd.

Nondispersive infrared spectrometry for 13CO2/12CO2-measurements: a clinically feasible analyzer for stable isotope breath tests in gastroenterology.

PubMed

Braden, B; Caspary, W F; Lembcke, B

1999-06-01

13C-urea breath tests have become clinical routine for the diagnosis of Helicobacter pylori infection and other isotope breath tests have been invented e.g. for gastric emptying or quantitative liver function testing. Recently, isotope-selective nondispersive infrared spectrometers (NDIRS) have been developed for the analysis of the 13CO2/12CO2-enrichment in breath. In this study, we prospectively tested the validity of a newly developed NDIRS in comparison to isotope ratio mass spectrometry (IRMS). 142 patients with dyspeptic symptoms were tested for Helicobacter pylori infection using the 13C-urea breath test. The isotope ratio analysis of the breath samples was performed in duplicate both using IRMS and NDIRS. The results of the baseline-corrected 13CO2-exhalation values between IRMS and NDIRS were in excellent agreement. The mean difference between both methods was 0.28 +/- 1.93 delta/1000. Evaluating the qualitative urea breath test results in reference to IRMS as the reference the NDIRS had a sensitivity of 97.8% and a specificity of 98.9%. The isotope-selective nondispersive infrared spectroscopy is going to become a reliable, but low-cost and easy-to-operate alternative to expensive isotope ratio mass spectrometry in the analysis of 13C-breath tests.

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.

Comprehensive inter-laboratory calibration of reference materials for δ18O versus VSMOW using various on-line high-temperature conversion techniques

USGS Publications Warehouse

Brand, Willi A.; Coplen, Tyler B.; Aerts-Bijma, Anita T.; Bohlke, John Karl; Gehre, Matthias; Geilmann, Heike; Groning, Manfred; Jansen, Henk G.; Meijer, Harro A. J.; Mroczkowski, Stanley J.; Qi, Haiping; Soergel, Karin; Stuart-Williams, Hilary; Weise, Stephan M.; Werner, Roland A.

2009-01-01

Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC) in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125‰, an artificially enriched reference water (δ18O of +78.91‰) and two barium sulfates (one depleted and one enriched in 18O) were prepared and calibrated relative to VSMOW2 and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study, which yielded:Reference materialδ18O and estimated combined uncertainty IAEA-602 benzoic acid+71.28 ± 0.36‰USGS35 sodium nitrate+56.81 ± 0.31‰IAEA-NO-3 potassium nitrate+25.32 ± 0.29‰IAEA-601 benzoic acid+23.14 ± 0.19‰IAEA-SO-5 barium sulfate+12.13 ± 0.33‰NBS 127 barium sulfate+8.59 ± 0.26‰VSMOW2 water0‰IAEA-600 caffeine−3.48 ± 0.53‰IAEA-SO-6 barium sulfate−11.35 ± 0.31‰USGS34 potassium nitrate−27.78 ± 0.37‰SLAP water−55.5‰The seemingly large estimated combined uncertainties arise from differences in instrumentation and methodology and difficulty in accounting for all measurement bias. They are composed of the 3-fold standard errors directly calculated from the measurements and provision for systematic errors discussed in this paper. A primary conclusion of this study is that nitrate samples analyzed for δ18O should be analyzed with internationally distributed isotopic nitrates, and likewise for sulfates and organics. Authors reporting relative differences of oxygen-isotope ratios (δ18O) of nitrates, sulfates, or organic material should explicitly state in their reports the δ18O values of two or more internationally distributed nitrates (USGS34, IAEA-NO-3, and USGS35), sulfates (IAEA-SO-5, IAEA-SO-6, and NBS 127), or organic material (IAEA-601 benzoic acid, IAEA-602 benzoic acid, and IAEA-600 caffeine), as appropriate to the material being analyzed, had these reference materials been analyzed with unknowns. This procedure ensures that readers will be able to normalize the δ18O values at a later time should it become necessary.The high-temperature reduction technique for analyzing δ18O and δ2H is not as widely applicable as the well-established combustion technique for carbon and nitrogen stable isotope determination. To obtain the most reliable stable isotope data, materials should be treated in an identical fashion; within the same sequence of analyses, samples should be compared with working reference materials that are as similar in nature and in isotopic composition as feasible.

Metrology for stable isotope reference materials: 13C/12C and 18O/16O isotope ratio value assignment of pure carbon dioxide gas samples on the Vienna PeeDee Belemnite-CO2 scale using dual-inlet mass spectrometry.

PubMed

Srivastava, Abneesh; Michael Verkouteren, R

2018-07-01

Isotope ratio measurements have been conducted on a series of isotopically distinct pure CO 2 gas samples using the technique of dual-inlet isotope ratio mass spectrometry (DI-IRMS). The influence of instrumental parameters, data normalization schemes on the metrological traceability and uncertainty of the sample isotope composition have been characterized. Traceability to the Vienna PeeDee Belemnite(VPDB)-CO 2 scale was realized using the pure CO 2 isotope reference materials(IRMs) 8562, 8563, and 8564. The uncertainty analyses include contributions associated with the values of iRMs and the repeatability and reproducibility of our measurements. Our DI-IRMS measurement system is demonstrated to have high long-term stability, approaching a precision of 0.001 parts-per-thousand for the 45/44 and 46/44 ion signal ratios. The single- and two-point normalization bias for the iRMs were found to be within their published standard uncertainty values. The values of 13 C/ 12 C and 18 O/ 16 O isotope ratios are expressed relative to VPDB-CO 2 using the [Formula: see text] and [Formula: see text] notation, respectively, in parts-per-thousand (‰ or per mil). For the samples, value assignments between (-25 to +2) ‰ and (-33 to -1) ‰ with nominal combined standard uncertainties of (0.05, 0.3) ‰ for [Formula: see text] and [Formula: see text], respectively were obtained. These samples are used as laboratory reference to provide anchor points for value assignment of isotope ratios (with VPDB traceability) to pure CO 2 samples. Additionally, they serve as potential parent isotopic source material required for the development of gravimetric based iRMs of CO 2 in CO 2 -free dry air in high pressure gas cylinder packages at desired abundance levels and isotopic composition values. Graphical abstract CO 2 gas isotope ratio metrology.

Using stable isotopes to resolve eco-hydrological dynamics of soil-plant-atmosphere feedbacks

NASA Astrophysics Data System (ADS)

Dubbert, M.; Piayda, A.; Kübert, A.; Cuntz, M.; Werner, C.

2016-12-01

Water is the main driver of ecosystem productivity in most terrestrial ecosystems worldwide. Extreme events are predicted to increase in frequency in many regions and dynamic responses in soil-vegetation-atmosphere feedbacks play a privotal role in understanding the ecosystem water balance and functioning. In this regard, more interdisciplinary approaches, bridging hydrology, ecophysiology and atmospheric sciences are needed and particularly water stable isotopes are a powerful tracer of water transfer in soils and at the soil-plant interface (Werner and Dubbert 2016). Here, we present observations 2 different ecosystems. Water fluxes, atmospheric concentrations and their isotopic compositions were measured using laser spectroscopy. Soil moisture and its isotopic composition in several depths as well as further water sources in the ecosystem were monitored throughout the year. Using these isotopic approaches we disentangled soil-plant-atmosphere feedback processes controlling the ecosystem water cycle including vegetation effects on soil water infiltration and distribution, event water use of vegetation and soil fluxes, vegetational soil water uptake depths plasticity and partitioning of ecosystem water fluxes. In this regard, we review current strategies of ET partitioning and highlight pitfalls in the presented strategies (Dubbert et al. 2013, Dubbert et al.2014a). We demonstrate that vegetation strongly influenced water cycling, altering infiltration and distribution of precipitation. In conclusion, application of stable water isotope tracers delivers a process based understanding of interactions between soil, understorey and trees governing ecosystem water cycling necessary for prediction of climate change impact on ecosystem productivity and vulnerability. ReferencesDubbert, M. et al. (2013): Partitioning evapotranspiration - Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes. Journal of Hydrology Dubbert, M. et al. (2014a): Oxygen isotope signatures of transpired water vapor: the role of isotopic non-steady-state transpiration under natural conditions. New Phytologist. Werner, C. and Dubbert, M. (2016): Resolving rapid dynamics of soil-plant-atmosphere interactions. New Phytologist.

Realistic Fasting Does Not Affect Stable Isotope Levels of a Metabolically Efficient Salamander

EPA Science Inventory

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

A Comparative Analysis of the Influence of Surface Mining on Hydrological and Geochemical Response of Selected Headwater Streams in the Elk Valley, British Columbia, Canada.

NASA Astrophysics Data System (ADS)

Carey, S. K.; Shatilla, N. J.; Szmudrowska, B.; Rastelli, J.; Wellen, C.

2014-12-01

Surface mining is a common method of accessing coal. Blasting of overburden rock allows access to mineable ore. In high-elevation environments, the removed overburden rock is deposited in adjacent valleys as waste rock spoils. As part of a multi-year R&D program examining the influence of surface mining on watershed hydrological and water quality responses in the Elk Valley, British Columbia, this study reports on how surface mining affects streamflow hydrological and geochemical response at four reference and four mine-influenced catchments. The hydrology of this environment is dominated by snowmelt and steep topographic gradients. Flows were attenuated in mine-influenced catchments, with spring freshet delayed and more muted responses to precipitation events observed. Dissolved ions were an order of magnitude greater in mine-influenced streams, with more dilution-based responses to flows compared with chemostatic behavior observed in reference streams. Stable isotope signatures in stream water suggested that in both mine-influenced and reference watersheds, stream water was derived from well mixed groundwater as annual variability of stream isotope signatures was dampened compared with precipitation signatures. However, deflection of stream isotopes in response to precipitation were more apparent in reference watersheds. As a group, mine influenced catchments had a heavier isotope signature than reference watersheds, suggesting an enhanced influence of rainfall on recharge. Transit time distributions indicate existing waste rock spoils increase the average time water takes to move through the catchment.

Mercury Stable Isotopic Composition of Monomethylmercury in Estuarine Sediments and Pure Cultures of Mercury Methylating Bacteria

NASA Astrophysics Data System (ADS)

Janssen, S.; Johnson, M. W.; Barkay, T.; Blum, J. D.; Reinfelder, J. R.

2014-12-01

Tracking monomethylmercury (MeHg) from its source in soils and sediments through various environmental compartments and transformations is critical to understanding its accumulation in aquatic and terrestrial food webs. Advances in the field of mercury (Hg) stable isotopes have allowed for the tracking of discrete Hg sources and the examination of photochemical and bacterial transformations. Despite analytical advances, measuring the Hg stable isotopic signature of MeHg in environmental samples or laboratory experiments remains challenging due to difficulties in the quantitative separation of MeHg from complex matrices with high concentrations of inorganic Hg. To address these challenges, we have developed a MeHg isolation method for sediments and bacterial cultures which involves separation by gas chromatography. The MeHg eluting from the GC is passed through a pyrolysis column and purged onto a gold amalgam trap which is then desorbed into a final oxidizing solution. A MeHg reference standard carried through our separation process retained its isotopic composition within 0.02 ‰ for δ202Hg, and for native estuarine sediments, MeHg recoveries were 80% to 100%. For sediment samples from the Hackensack and Passaic Rivers (New Jersey, USA), δ202Hg values for MeHg varied from -1.2 to +0.58 ‰ (relative to SRM 3133) and for individual samples were significantly different from that of total Hg (-0.38 ± 0.06 ‰). No mass independent fractionation was observed in MeHg or total Hg from these sediments. Pure cultures of Geobacter sulfurreducens, grown under fermentative conditions showed preferential enrichment of lighter isotopes (lower δ202Hg) during Hg methylation. The Hg stable isotope signatures of MeHg in sediments and laboratory methylation experiments will be discussed in the context of the formation and degradation of MeHg in the environment and the bioaccumulation of MeHg in estuarine food webs.

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

NASA Astrophysics Data System (ADS)

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

2016-04-01

Carbon stable-isotope stratigraphy of marine carbonates (δ13Ccarb) provides remarkable insights into past variation in the global carbon cycle, and has become firmly established as a powerful global correlation tool. Continuous δ13Ccarb time series are becoming increasingly available for much of the geological record, including the Upper Cretaceous. However, our knowledge of stratigraphic variation in the carbon isotopic composition of sedimentary organic matter (δ13Corg) is much poorer, and is generally restricted to organic-rich sedimentary successions and/or key boundary intervals. Close coupling exists between the global isotopic composition of the reduced and oxidised carbon reservoirs on geological time scales, but the stratigraphic resolution of most long-term δ13Corg Mesozoic records is inadequate to identify leads and lags in the responses of the two reservoirs to carbon cycle perturbations. Cenomanian times (100.5-93.9 Ma) represent perhaps the best documented episode of eustatic rise in sea level in Earth history and the beginning of the Late Mesozoic thermal maximum, driving global expansion of epicontinental seas and the onset of widespread pelagic and hemipelagic carbonate deposition. Significant changes occurred in global stable-isotope records, including two prominent perturbations of the carbon cycle - the Mid-Cenomanian Event I (MCEI; ~96.5-96.2 Ma) and Oceanic Anoxic Event 2 (OAE2; ~94.5-93.8 Ma). OAE2, one of two truly global Cretaceous OAEs, was marked by the widespread deposition of black shales, and a global positive carbon stable-isotope excursion of 2.0 - 2.5‰ δ13Ccarb, and up to 7‰ in the sulphur-bound phytane biomarker. MCEI, by contrast, shows a <1‰ δ13Ccarb excursion and no associated black shales in most areas. Here, we present detailed paired δ13Ccarb and δ13Corg stable-isotope records for the entire Cenomanian Stage, based on an Upper Albian - Lower Turonian composite reference section from the Vocontian Basin of SE France. We compare the δ13Ccarb profile to new results from the English Chalk reference section at Folkestone, and correlate the carbon-isotope events between England, France, Germany and Italy. Comparison of the Vergons δ13Ccarb vs. δ13Corg profiles demonstrates similar medium-term stratigraphic variation, but significant differences in both short- and long-term trends. Potential causes of the similarities and differences are examined, and it is concluded that major deviations of the paired isotope trends offer insights into long-term atmospheric pCO2 variation. The osmium 187Os/188Os isotope stratigraphy of the MCEI and OAE2 intervals provides evidence of varying volcanic CO2 input, in-part driving climate change. Spectral analyses of the δ13Corg time series reveals a strong ~100 kyr short eccentricity signal throughout the Cenomanian, with well-expressed ~40 kyr obliquity and ~20 kyr precession cycles in some intervals. A 400 kyr long eccentricity cycle is recorded in sedimentation rate changes and amplitude modulation of the 100 kyr cycle. The relative spacing of events, and comparison with the latest orbital solution La2011, further suggest that MCE I and OAE2 coincided with nodes in the ~2.2-Myr eccentricity modulation.

Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil

USGS Publications Warehouse

Qi, Haiping; Coplen, Tyler B.; Geilmann, Heike; Brand, Willi A.; Böhlke, J.K.

2003-01-01

Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a δ13C value of −26.24‰ relative to VPDB and a δ15N value of −4.52‰ relative to N2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in 13C and 15N. USGS41 has a δ13C value of +37.76‰ and a δ15N value of +47.57‰. The δ13C and δ15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (δ13C = +1.95‰), L-SVEC lithium carbonate (δ13C = −46.48‰), IAEA-N-1 ammonium sulfate (δ15N = 0.43‰), and USGS32 potassium nitrate (δ15N = 180‰) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of δ13C is better than 0.13‰, and that of δ15N is better than 0.13‰ in 100-μg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a δ13C value for NBS 22 oil of −29.91‰, in contrast to the commonly accepted value of −29.78‰ for which off-line blank corrections probably have not been quantified satisfactorily.

[Measurements of stable isotopes in atmospheric CO2 and H2O by open-path Fourier transform infrared spectrometry].

PubMed

Wang, Wei; Liu, Wen-Qing; Zhang, Tian-Shu

2013-08-01

The development of spectroscopic techniques has offered continuous measurement of stable isotopes in the ambient air. The method of measuring environmental stable isotopes based on Fourier transform infrared spectrometry (FTIR) is described. In order to verify the feasibility of the method for continuous measurement of the stable isotopes, an open-path FTIR system was used to measure stable isotopes of CO2 and H2O in ambient air directly in a seven-day field experiment, including 12CO2, 3CO2, H2 16O and HD16 O. Also, the time course of carbon isotopic ratio delta13 C and deuterium isotope composition deltaD was calculated. The measurement precision is about 1.08 per thousand for delta13 C and 1.32 per thousand for deltaD. The measured stable isotopes of CO2 and H2O were analyzed on different time scales by Keeling plot methods, and the deuterium isotopic ratios of evapotranspiration were determined. The results of the field experiment demonstrate the potential of the open-path FTIR system for continuous measurement of stable isotopes in the air.

Stable oxygen and hydrogen isotopes of brines - comparing isotope ratio mass spectrometry and isotope ratio infrared spectroscopy

NASA Astrophysics Data System (ADS)

Ahrens, Christian; Koeniger, Paul; van Geldern, Robert; Stadler, Susanne

2013-04-01

Today's standard analytical methods for high precision stable isotope analysis of fluids are gas-water equilibration and high temperature pyrolysis coupled to isotope ratio mass spectrometers (IRMS). In recent years, relatively new laser-based analytical instruments entered the market that are said to allow high isotope precision data on nearly every media. This optical technique is referred to as isotope ratio infrared spectroscopy (IRIS). The objective of this study is to evaluate the capability of this new instrument type for highly saline solutions and a comparison of the analytical results with traditional IRMS analysis. It has been shown for the equilibration method that the presence of salts influences the measured isotope values depending on the salt concentration (see Lécuyer et al, 2009; Martineau, 2012). This so-called 'isotope salt effect' depends on the salt type and salt concentration. These factors change the activity in the fluid and therefore shift the isotope ratios measured by the equilibration method. Consequently, correction factors have to be applied to these analytical data. Direct conversion techniques like pyrolysis or the new laser instruments allow the measurement of the water molecule from the sample directly and should therefore not suffer from the salt effect, i.e. no corrections of raw values are necessary. However, due to high salt concentrations this might cause technical problems with the analytical hardware and may require labor-intensive sample preparation (e.g. vacuum distillation). This study evaluates the salt isotope effect for the IRMS equilibration technique (Thermo Gasbench II coupled to Delta Plus XP) and the laser-based IRIS instruments with liquid injection (Picarro L2120-i). Synthetic salt solutions (NaCl, KCl, CaCl2, MgCl2, MgSO4, CaSO4) and natural brines collected from the Stassfurt Salt Anticline (Germany; Stadler et al., 2012) were analysed with both techniques. Salt concentrations ranged from seawater salinity up to full saturation. References Lécuyer, C. et al. (2009). Chem. Geol., 264, 122-126. [doi:10.1016/j.chemgeo.2009.02.017] Martineau, F. et al. (2012). Chem. Geol., 291, 236-240. [doi:10.1016/j.chemgeo.2011.10.017] Stadler, S. et al. (2012). Chem. Geol., 294-295, 226-242. [doi:10.1016/j.chemgeo.2011.12.006

ICP-MS for isotope ratio measurement

USDA-ARS?s Scientific Manuscript database

The use of stable isotopes in mineral nutrition research has become a fundamental aspect of conducting this research. A gradual transition has occurred, now virtually complete, from radioactive isotope studies to those using stable isotopes. Although primarily used in human research, mineral stable ...

13C and 15N fractionation of CH4/N2 mixtures during photochemical aerosol formation: Relevance to Titan

NASA Astrophysics Data System (ADS)

Sebree, Joshua A.; Stern, Jennifer C.; Mandt, Kathleen E.; Domagal-Goldman, Shawn D.; Trainer, Melissa G.

2016-05-01

The ratios of the stable isotopes that comprise each chemical species in Titan's atmosphere provide critical information towards understanding the processes taking place within its modern and ancient atmosphere. Several stable isotope pairs, including 12C/13C and 14N/15N, have been measured in situ or probed spectroscopically by Cassini-borne instruments, space telescopes, or through ground-based observations. Current attempts to model the observed isotope ratios incorporate fractionation resulting from atmospheric diffusion, hydrodynamic escape, and primary photochemical processes. However, the effect of a potentially critical pathway for isotopic fractionation - organic aerosol formation and subsequent deposition onto the surface of Titan - has not been considered due to insufficient data regarding fractionation during aerosol formation. To better understand the nature of this process, we have conducted a laboratory study to measure the isotopic fractionation associated with the formation of Titan aerosol analogs, commonly referred to as 'tholins', via far-UV irradiation of several methane (CH4) and dinitrogen (N2) mixtures. Analysis of the δ13C and δ15N isotopic signatures of the photochemical aerosol products using an isotope ratio mass spectrometer (IRMS) show that fractionation direction and magnitude are dependent on the initial bulk composition of the gas mixture. In general, the aerosols showed enrichment in 13C and 14N, and the observed fractionation trends can provide insight into the chemical mechanisms controlling photochemical aerosol formation.

Electrochemically controlled iron isotope fractionation

NASA Astrophysics Data System (ADS)

Black, Jay R.; Young, Edward D.; Kavner, Abby

2010-02-01

Variations in the stable isotope abundances of transition metals have been observed in the geologic record and trying to understand and reconstruct the physical/environmental conditions that produced these signatures is an area of active research. It is clear that changes in oxidation state lead to large fractionations of the stable isotopes of many transition metals such as iron, suggesting that transition metal stable isotope signatures could be used as a paleo-redox proxy. However, the factors contributing to these observed stable isotope variations are poorly understood. Here we investigate how the kinetics of iron redox electrochemistry generates isotope fractionation. Through a combination of electrodeposition experiments and modeling of electrochemical processes including mass-transport, we show that electron transfer reactions are the cause of a large isotope separation, while mass transport-limited supply of reactant to the electrode attenuates the observed isotopic fractionation. Furthermore, the stable isotope composition of electroplated transition metals can be tuned in the laboratory by controlling parameters such as solution chemistry, reaction overpotential, and solution convection. These methods are potentially useful for generating isotopically-marked metal surfaces for tracking and forensic purposes. In addition, our studies will help interpret stable isotope data in terms of identifying underlying electron transfer processes in laboratory and natural samples.

Watershed Scale Stable Isotope Distribution and Implications on Soil Organic Carbon Loss Monitoring under Hydrologic Uncertainty

NASA Astrophysics Data System (ADS)

Ahmed, I.; Karim, A.; Boutton, T. W.; Strom, K.; Fox, J.

2013-12-01

The thematic focus of this 3-year period multidisciplinary USDA-CBG collaborative applied research is integrated monitoring of soil organic carbon (SOC) loss from multi-use lands using state-of-the-art stable isotope science under uncertain hydrologic influences. In this study, SOC loss and water runoff are being monitored on a 150 square kilometer watershed in Houston, Texas, using natural rainfall events, and total organic carbon/nitrogen concentration (TOC/TN) and stable isotope ratio (δ13C, δ15N) measurements with different land-use types. The work presents the interdisciplinary research results to uncover statistically valid and scientifically sound ways to monitor SOC loss by (i) application of Bayesian Markov Chain Monte Carlo statistical models to assess the relationship between rainfall-runoff and SOC release during soil erosion in space and time, (ii) capturing the episodic nature of rainfall events and its role in the spatial distribution of SOC loss from water erosion, (iii) stable isotope composition guided fingerprinting (source and quantity) of SOC by considering various types of erosion processes common in a heterogeneous watershed, to be able to tell what percentage of SOC is lost from various land-use types (Fox and Papanicolaou, 2008), (iv) creating an integrated watershed scale statistical soil loss monitoring model driven by spatial and temporal correlation of flow and stable isotope composition (Ahmed et. al., 2013a,b), and (v) creation of an integrated decision support system (DSS) for sustainable management of SOC under hydrologic uncertainty to assist the end users. References: Ahmed, I., Karim, A., Boutton, T.W., and Strom, K.B. (2013a). 'Monitoring Soil Organic Carbon Loss from Erosion Using Stable Isotopes.' Proc., Soil Carbon Sequestration, International Conference, May 26-29, Reykjavik, Iceland. Ahmed, I, Bouttom, T.W., Strom, K. B., Karim, A., and Irvin-Smith, N. (2013b). 'Soil carbon distribution and loss monitoring in the urbanized Buffalo Bayou watershed, Houston, Texas.' Proc., 4th Annual All Investigators Meeting of the North American Carbon Program, February 4-7, Albuquerque, NM. Fox, J.F. and Papanicolaou, A.N. (2008). An un-mixing model to study watershed erosion processes. Advances in Water Resources, 31, 96-108. ______________________________ * Corresponding author';s e-mail: ifahmed@pvamu.edu

[Research advances in identifying nitrate pollution sources of water environment by using nitrogen and oxygen stable isotopes].

PubMed

Mao, Wei; Liang, Zhi-wei; Li, Wei; Zhu, Yao; Yanng, Mu-yi; Jia, Chao-jie

2013-04-01

Water body' s nitrate pollution has become a common and severe environmental problem. In order to ensure human health and water environment benign evolution, it is of great importance to effectively identify the nitrate pollution sources of water body. Because of the discrepant composition of nitrogen and oxygen stable isotopes in different sources of nitrate in water body, nitrogen and oxygen stable isotopes can be used to identify the nitrate pollution sources of water environment. This paper introduced the fractionation factors of nitrogen and oxygen stable isotopes in the main processes of nitrogen cycling and the composition of these stable isotopes in main nitrate sources, compared the advantages and disadvantages of five pre-treatment methods for analyzing the nitrogen and oxygen isotopes in nitrate, and summarized the research advances in this aspect into three stages, i. e. , using nitrogen stable isotope alone, using nitrogen and oxygen stable isotopes simultaneously, and combining with mathematical models. The future research directions regarding the nitrate pollution sources identification of water environment were also discussed.

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...

222Rn+220Rn monitoring by alpha spectrometry.

PubMed

Buompane, R; Roca, V; Sabbarese, C; Pugliese, M; Quarto, M; Mattone, C

2014-07-01

Controlled 222Rn+220Rn mixed atmospheres have been realised introducing calibrated sources in a stainless steel chamber. An electrostatic alpha monitor internal to the chamber has been used for an accurate discrimination of alpha peaks due to the products of the two isotopes. In the chamber, different specific activities are achieved in order to test the response of the internal reference instrument and to evaluate the possible interferences due to contemporary presence of both radon isotopes. Results show that: (i) the atmospheres are very stable, (ii) the monitor is adequate for their control because the various alpha lines are well evaluated and (iii) using Tyvek® filter, the efficiency of monitor is stable and constant vs. activity. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Analysis of stable isotopes in fish to identify habitat use and switching

EPA Science Inventory

In our isotopic studies of fish in Oregon Coast Range streams we have found stable isotopes of carbon, oxygen and sulfur to be surprisingly useful in identifying and discriminating specific habitat or tributary use by a variety of fish species. Stable isotopes of carbon can be u...

Stable isotopes in fish as indicators of habitat use

EPA Science Inventory

In our isotopic studies of fish in Oregon Coast Range streams we have found stable isotopes of carbon, oxygen and sulfur to be surprisingly useful in identifying and discriminating specific habitat or tributary use by a variety of fish species. Stable isotopes of carbon can be u...

Stable isotope views on ecosystem function: challenging or challenged?

PubMed

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

2010-06-23

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

Stable isotope views on ecosystem function: challenging or challenged?

PubMed Central

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

2010-01-01

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

Stable isotope and gas properties of two ice wedges from Cape Mamontov Klyk, Laptev Sea, Northern Siberia

NASA Astrophysics Data System (ADS)

Boereboom, T.; Samyn, D.; Meyer, H.; Tison, J.-L.

2011-12-01

This paper presents and discusses the texture, fabric and gas properties (contents of total gas, O2, N2, CO2, and CH4) of two ice wedges from Cape Mamontov Klyk, Laptev Sea, Northern Siberia. The two ice wedges display contrasting structures: one being of relatively "clean" ice and the other showing clean ice at its centre as well as debris-rich ice on its sides (referred to as ice-sand wedge). A comparison of gas properties, crystal size, fabrics and stable isotope data (δ18O and δD) allows discriminating between three different facies of ice with specific paleoenvironmental signatures, suggesting different climatic conditions and rates of biological activity. More specifically, total gas content and composition reveal variable intensities of meltwater infiltration and show the impact of biological processes with contrasting contributions from anaerobic and aerobic conditions. Stable isotope data are shown to be valid for discussing changes in paleoenvironmental conditions and/or decipher different sources for the snow feeding into the ice wedges with time. Our data also give support to the previous assumption that the composite ice wedge was formed in Pleistocene and the ice wedge in Holocene times. This study sheds more light on the conditions of ice wedge growth under changing environmental conditions.

A Collection of Chemical, Mineralogical, and Stable Isotopic Compositional Data for Green River Oil Shale from Depositional Center Cores in Colorado, Utah, and Wyoming

USGS Publications Warehouse

Tuttle, Michele L.W.

2009-01-01

For over half a century, the U.S. Geological Survey and collaborators have conducted stratigraphic and geochemical studies on the Eocene Green River Formation, which is known to contain large oil shale resources. Many of the studies were undertaken in the 1970s during the last oil shale boom. One such study analyzed the chemistry, mineralogy, and stable isotopy of the Green River Formation in the three major depositional basins: Piceance basin, Colo.; Uinta basin, Utah; and the Green River basin, Wyo. One depositional-center core from each basin was sampled and analyzed for major, minor, and trace chemistry; mineral composition and sulfide-mineral morphology; sulfur, nitrogen, and carbon forms; and stable isotopic composition (delta34S, delta15N, delta13C, and delta18O). Many of these data were published and used to support interpretative papers (see references herein). Some bulk-chemical and carbonate-isotopic data were never published and may be useful to studies that are currently exploring topics such as future oil shale development and the climate, geography, and weathering in the Eocene Epoch. These unpublished data, together with most of the U.S. Geological Survey data already published on these samples, are tabulated in this report.

Improvements in Precise and Accurate Isotope Ratio Determination via LA-MC-ICP-MS by Application of an Alternative Data Reduction Protocol

NASA Astrophysics Data System (ADS)

Fietzke, J.; Liebetrau, V.; Guenther, D.; Frische, M.; Zumholz, K.; Hansteen, T. H.; Eisenhauer, A.

2008-12-01

An alternative approach for the evaluation of isotope ratio data using LA-MC-ICP-MS will be presented. In contrast to previously applied methods it is based on the simultaneous responses of all analyte isotopes of interest and the relevant interferences without performing a conventional background correction. Significant improvements in precision and accuracy can be achieved when applying this new method and will be discussed based on the results of two first methodical applications: a) radiogenic and stable Sr isotopes in carbonates b) stable chlorine isotopes of pyrohydrolytic extracts. In carbonates an external reproducibility of the 87Sr/86Sr ratios of about 19 ppm (RSD) was achieved, an improvement of about a factor of 5. For recent and sub-recent marine carbonates a mean radiogenic strontium isotope ratio 87Sr/86Sr of 0.709170±0.000007 (2SE) was determined, which agrees well with the value of 0.7091741±0.0000024 (2SE) reported for modern sea water [1,2]. Stable chlorine isotope ratios were determined ablating pyrohydrolytic extracts with a reproducibility of about 0.05‰ (RSD). For basaltic reference material JB1a and JB2 chlorine isotope ratios were determined relative to SMOC (standard mean ocean chlorinity) δ37ClJB-1a = (-0.99±0.06) ‰ and δ37ClJB-1a = (-0.60±0.03) ‰ (SD), respectively, in accordance with published data [3]. The described strategies for data reduction are considered to be generally applicable for all isotope ratio measurements using LA-MC-ICP-MS. [1] J.M. McArthur, D. Rio, F. Massari, D. Castradori, T.R. Bailey, M. Thirlwall, S. Houghton, Palaeogeo. Palaeoclim. Palaeoeco., 2006, 242 (126), doi: 10.1016/j.palaeo.2006.06.004 [2] J. Fietzke, V. Liebetrau, D. Guenther, K. Guers, K. Hametner, K. Zumholz, T.H. Hansteen and A. Eisenhauer, J. Anal. At. Spectrom., 2008, 23, 955-961, doi:10.1039/B717706B [3] J. Fietzke, M. Frische, T.H. Hansteen and A. Eisenhauer, J. Anal. At. Spectrom., 2008, 23, 769-772, doi:10.1039/B718597A

O and H Isotope Ratios of Syenite Blocks in the El Abrigo Ignimbrite, Tenerife, Canary Islands: A Hydrothermal Fingerprint for Assimilation

NASA Astrophysics Data System (ADS)

Larson, P. B.; Nichols, H. J.; Wolff, J. A.; Marti, J.

2001-12-01

As part of an ongoing project investigating assimilation in ocean island magmas, we are measuring stable isotope ratios of hydrothermally altered lithic fragments in phonolitic pyroclastic deposits from Tenerife, Canary Islands. Nepheline syenite blocks occur in the 0.196 Ma El Abrigo ignimbrite of the Diego Hernandez Formation (DHF). The DHF is the most recent of at least three caldera-forming magmatic cycles on Tenerife. The blocks are fragments of evolved plutons that are chemically similar to phonolites but extend to more strongly differentiated compositions. Distinct major and trace element concentrations suggest that the blocks derive from two intrusions, here referred to as A and B. The B syenites have chemical affinities with the El Abrigo phonolite, and some blocks contain small pockets of residual glass, suggesting that the B pluton may have been coeval with the El Abrigo magma. O isotope ratios of the B syenites lie within the range 4.8 to 7.0 per mil. The B samples are mostly fresh, and their higher O isotope ratios are near pristine magmatic values. Lower values occur in rocks with mild hydrothermal mineralogic alteration, and their values reflect limited high-temperature water-rock isotope exchange. O isotope ratios for A blocks are lower (0.1 to 6.3 per mil, most less than 2.0 per mil), and some samples show extensive mineral alteration. Near-ubiquitous alteration among the A samples, distinct major and trace element compositions, and lack of glass show that this syenite was older than, and unrelated to, the El Abrigo magma. Syenite D/H ratios range from -90 to -120 per mil. O vs H isotope relations indicate that an 18O-depleted meteoric water was the most important reservoir for the high-temperature hydrothermal fluid. Assimilation of altered syenite should provide a distinct stable isotope fingerprint that would be inherited by the product magma. DHF phonolites yield O ratios in the range 5.5 to 7.0 per mil, which may be this fingerprint. Assimilation of variably altered syenites, with accompanying fractionation, is a viable mechanism for producing this stable isotope variability in the magmas.

Temporal and spatial variability in stable isotope compositions of a freshwater mussel: Implications for biomonitoring and ecological studies

USGS Publications Warehouse

Gustafson, L.; Showers, W.; Kwak, T.; Levine, J.; Stoskopf, M.

2007-01-01

Stable isotopes can be used to elucidate ecological relationships in community and trophic studies. Findings are calibrated against baselines, e.g. from a producer or primary consumer, assumed to act as a reference to the isotopic context created by spatio-temporal attributes such as geography, climate, nutrient, and energy sources. The ability of an organism to accurately represent a community base depends on how, and over what time-scale, it assimilates ambient materials. Freshwater mussels have served as references for trophic studies of freshwater communities and as indicators of change in nutrient pollution load or source. Their suitability as reference animals has not yet been fully explored, however. We conducted a series of studies examining the suitability of freshwater mussels as isotopic baselines, using their ability to reflect variation in ambient nutrient loads as a case scenario. (1) We analyzed bivalve foot tissue ??15N and ??13C from 22 stream reaches in the Piedmont region of North Carolina, USA to show that compositions varied substantially among locations. Site mean bivalve ??13C values correlated with site ambient particulate organic matter (POM) ??13C values, and site mean bivalve ??15N values correlated with site ambient water dissolved ??15N-NO3 values. (2) Similarity of results among sample types demonstrated that the minimally invasive hemolymph sample is a suitable substitute for foot tissue in ??15N analyses, and that small sample sizes generate means representative of a larger population. Both findings can help minimize the impact of sampling on imperiled freshwater mussel populations. (3) In a bivalve transplantation study we showed that hemolymph ??15N compositions responded to a shift in ambient dissolved ??15N-NO3, although slowly. The tissue turnover time for bivalve hemolymph was 113 days. We conclude that bivalves serve best as biomonitors of chronic, rather than acute, fluctuations in stream nutrient loads, and provide initial evidence of their suitability as time-integrated isotopic baselines for community studies. ?? 2006 Springer-Verlag.

Stable mineral recrystallization in low temperature aqueous systems: A critical review

NASA Astrophysics Data System (ADS)

Gorski, Christopher A.; Fantle, Matthew S.

2017-02-01

Minerals may undergo recrystallization reactions in low temperature (<100 °C) aqueous systems, during which they exchange isotopes and trace elements with the dissolved reservoir without undergoing overt structural, bulk compositional, or morphological changes. These interfacial reactions, which are often referred to in the literature as "atom exchange" and herein as "stable mineral recrystallization", have important implications for the use of isotopic and elemental proxies to interpret past temperatures, oxidation states, and aqueous chemistries on Earth. The reactions are also significant for modern environments, including engineered systems, as they imply that mineral lattices may be substantially more open to exchanging toxic elements and radionuclides with coexisting solutions than previously thought. To date, observations of stable mineral recrystallization are distributed among several disciplines, and no work has attempted to review their findings comprehensively. Accordingly, this review article presents laboratory evidence for stable mineral recrystallization, describes data collection and interpretation strategies, summarizes similar recrystallization systematics observed in multiple studies, explores the potential occurrence of stable mineral recrystallization in natural systems, and discusses possible mechanisms by which stable mineral recrystallization occurs. The review focuses primarily on carbonates, sulfates, and iron oxides because these minerals have been studied most extensively to date. The review concludes by presenting key questions that should be addressed in this field to further understand and account for stable mineral recrystallization in natural and engineered aqueous systems at low temperatures.

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

USDA-ARS?s Scientific Manuscript database

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

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

Treesearch

Jeffrey F. Kelly

2000-01-01

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

Quantifying uncertainty in stable isotope mixing models

DOE PAGES

Davis, Paul; Syme, James; Heikoop, Jeffrey; ...

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 (δ 15N and δ 18O) butmore » all methods tested are applicable to other tracers. In Phase I of a three-phase blind test, we compared methods for a set of six-source nitrate problems. PMC was unable to find solutions for two of the target water samples. The Bayesian method, SIAR, experienced anchoring problems, and SIRS calculated mixing fractions that most closely approximated the known mixing fractions. For that reason, SIRS was the only approach used in the next phase of testing. In Phase II, the problem was broadened where any subset of the six sources could be a possible solution to the mixing problem. Results showed a high rate of Type I errors where solutions included sources that were not contributing to the sample. In Phase III some sources were eliminated based on assumed site knowledge and assumed nitrate concentrations, substantially reduced mixing fraction uncertainties and lowered the Type I error rate. These results demonstrate that valuable insights into stable isotope mixing problems result from probabilistic mixing model approaches like SIRS. The results also emphasize the importance of identifying a minimal set of potential sources and quantifying uncertainties in source isotopic composition as well as demonstrating the value of additional information in reducing the uncertainty in calculated mixing fractions.« less

Stable-isotope fingerprints of biological agents as forensic tools.

PubMed

Horita, Juske; Vass, Arpad A

2003-01-01

Naturally occurring stable isotopes of light elements in chemical and biological agents may possess unique "stable-isotope fingerprints" depending on their sources and manufacturing processes. To test this hypothesis, two strains of bacteria (Bacillus globigii and Erwinia agglomerans) were grown under controlled laboratory conditions. We observed that cultured bacteria cells faithfully inherited the isotopic composition (hydrogen, carbon, and nitrogen) of media waters and substrates in predictable manners in terms of bacterial metabolism and that even bacterial cells of the same strain, which grew in media water and substrates of different isotopic compositions, have readily distinguishable isotopic signatures. These "stable-isotopic fingerprints" of chemical and biological agents can be used as forensic tools in the event of biochemical terrorist attacks.

What can one sample tell us? Stable isotopes can assess complex processes in national assessments of lakes, rivers and streams.

EPA Science Inventory

Stable isotopes can be very useful in large-scale monitoring programs because samples for isotopic analysis are easy to collect, and isotopes integrate information about complex processes such as evaporation from water isotopes and denitrification from nitrogen isotopes. Traditi...

Palaeoclimate signal recorded by stable isotopes in cave ice: a modeling approach

NASA Astrophysics Data System (ADS)

Perşoiu, A.; Bojar, A.-V.

2012-04-01

Ice accumulations in caves preserve a large variety of geochemical information as candidate proxies for both past climate and environmental changes, one of the most significant being the stable isotopic composition of the ice. A series of recent studies have targeted oxygen and hydrogen stable isotopes in cave ice as proxies for past air temperatures, but the results are far from being as straightforward as they are in high latitude and altitude glaciers and ice caps. The main problems emerging from these studies are related to the mechanisms of cave ice formation (i.e., freezing of water) and post-formation processes (melting and refreezing), which both alter the original isotopic signal in water. Different methods have been put forward to solve these issues and a fair understanding of the present-day link between stable isotopes in precipitation and cave ice exists now. However, the main issues still lays unsolved: 1) is it possible to extend this link to older ice and thus reconstruct past changes in air temperature?; 2) to what extent are ice dynamics processes modifying the original climatic signal and 3) what is the best method to be used in extracting a climatic signal from stable isotopes in cave ice? To respond to these questions, we have conducted a modeling experiment, in which a theoretical cave ice stable isotope record was constructed using present-day observations on stable isotope behavior in cave ice and ice dynamics, and different methods (presently used for both polar and cave glaciers), were used to reconstruct the original, known, isotopic values. Our results show that it is possible to remove the effects of ice melting and refreezing on stable isotope composition of cave ice, and thus reconstruct the original isotopic signal, and further the climatic one.

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

NASA Astrophysics Data System (ADS)

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

1997-02-01

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

Advances in natural stable isotope ratio analysis of human hair to determine nutritional and metabolic status.

PubMed

Petzke, Klaus J; Fuller, Benjamin T; Metges, Cornelia C

2010-09-01

We review the literature on the use of stable isotope ratios at natural abundance to reveal information about dietary habits and specific nutrient intakes in human hair protein (keratin) and amino acids. In particular, we examine whether hair isotopic compositions can be used as unbiased biomarkers to provide information about nutritional status, metabolism, and diseases. Although the majority of research on the stable isotope ratio analysis of hair has focused on bulk protein, methods have been recently employed to examine amino acid-specific isotope ratios using gas chromatography or liquid chromatography coupled to an isotope ratio mass spectrometer. The isotopic measurement of amino acids has the potential to answer research questions on amino acid nutrition, metabolism, and disease processes and can contribute to a better understanding of the variations in bulk protein isotope ratio values. First results suggest that stable isotope ratios are promising as unbiased nutritional biomarkers in epidemiological research. However, variations in stable isotope ratios of human hair are also influenced by nutrition-dependent nitrogen balance, and more controlled clinical research is needed to examine these effects in human hair. Stable isotope ratio analysis at natural abundance in human hair protein offers a noninvasive method to reveal information about long-term nutritional exposure to specific nutrients, nutritional habits, and in the diagnostics of diseases leading to nutritional stress and impaired nitrogen balance.

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

PubMed

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

2015-03-03

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

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

DOEpatents

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

2014-12-09

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

Titanium stable isotope investigation of magmatic processes on the Earth and Moon

NASA Astrophysics Data System (ADS)

Millet, Marc-Alban; Dauphas, Nicolas; Greber, Nicolas D.; Burton, Kevin W.; Dale, Chris W.; Debret, Baptiste; Macpherson, Colin G.; Nowell, Geoffrey M.; Williams, Helen M.

2016-09-01

We present titanium stable isotope measurements of terrestrial magmatic samples and lunar mare basalts with the aims of constraining the composition of the lunar and terrestrial mantles and evaluating the potential of Ti stable isotopes for understanding magmatic processes. Relative to the OL-Ti isotope standard, the δ49Ti values of terrestrial samples vary from -0.05 to +0.55‰, whereas those of lunar mare basalts vary from -0.01 to +0.03‰ (the precisions of the double spike Ti isotope measurements are ca. ±0.02‰ at 95% confidence). The Ti stable isotope compositions of differentiated terrestrial magmas define a well-defined positive correlation with SiO2 content, which appears to result from the fractional crystallisation of Ti-bearing oxides with an inferred isotope fractionation factor of ΔTi49oxide-melt = - 0.23 ‰ ×106 /T2. Primitive terrestrial basalts show no resolvable Ti isotope variations and display similar values to mantle-derived samples (peridotite and serpentinites), indicating that partial melting does not fractionate Ti stable isotopes and that the Earth's mantle has a homogeneous δ49Ti composition of +0.005 ± 0.005 (95% c.i., n = 29). Eclogites also display similar Ti stable isotope compositions, suggesting that Ti is immobile during dehydration of subducted oceanic lithosphere. Lunar basalts have variable δ49Ti values; low-Ti mare basalts have δ49Ti values similar to that of the bulk silicate Earth (BSE) while high-Ti lunar basalts display small enrichment in the heavy Ti isotopes. This is best interpreted in terms of source heterogeneity resulting from Ti stable isotope fractionation associated with ilmenite-melt equilibrium during the generation of the mantle source of high-Ti lunar mare basalts. The similarity in δ49Ti between terrestrial samples and low-Ti lunar basalts provides strong evidence that the Earth and Moon have identical stable Ti isotope compositions.

Stable carbon, oxygen, and nitrogen, isotope analysis of plants from a South Asian tropical forest: Implications for primatology.

PubMed

Roberts, Patrick; Blumenthal, Scott A; Dittus, Wolfgang; Wedage, Oshan; Lee-Thorp, Julia A

2017-06-01

Stable isotope analysis of primate tissues in tropical forest contexts is an increasingly popular means of obtaining information about niche distinctions among sympatric species, including preferences in feeding height, forest canopy density, plant parts, and trophism. However, issues of equifinality mean that feeding height, canopy density, as well as the plant parts and plant species consumed, may produce similar or confounding effects. With a few exceptions, researchers have so far relied largely on general principles and/or limited plant data from the study area as references for deducing the predominant drivers of primate isotope variation. Here, we explore variation in the stable carbon (δ 13 C), nitrogen (δ 15 N), and oxygen (δ 18 O) isotope ratios of 288 plant samples identified as important to the three primate species from the Polonnaruwa Nature Sanctuary, Sri Lanka, relative to plant part, season, and canopy height. Our results show that plant part and height have the greatest effect on the δ 13 C and δ 18 O measurements of plants of immediate relevance to the primates, Macaca sinica, Semnopithecus priam thersites, and Trachypithecus vetulus, living in this monsoonal tropical forest. We find no influence of plant part, height or season on the δ 15 N of measured plants. While the plant part effect is particularly pronounced in δ 13 C between fruits and leaves, differential feeding height, and plant taxonomy influence plant δ 13 C and δ 18 O differences in addition to plant organ. Given that species composition in different regions and forest types will differ, the results urge caution in extrapolating general isotopic trends without substantial local baselines studies. © 2017 Wiley Periodicals, Inc.

Safety of stable isotope use.

PubMed

Koletzko, B; Sauerwald, T; Demmelmair, H

1997-08-01

The increased employment of stable isotope tracers for diagnostic and research purposes frequently raises questions on potential risks associated with their use, which is of particular importance in the paediatric age group. Biological effects and the potential of adverse events has been evaluated in a large number of animal and, in part, also human studies. Possible differences in physical, chemical and biochemical behaviour resulting in kinetic and thermodynamic isotope effects between stable isotopes of the same element are related to the relative differences in atomic weight. Deuterium (2H), which differs markedly in mass from the predominant hydrogen isotope 1H, may induce serious side-effects at high concentrations in body fluids. The threshold dose for the occurrence of side-effects lies well above the usual tracer dosages for clinical use. In contrast to deuterium, heavier stable isotopes such as 13C, 15N or 18O that differ relatively little in mass from the predominant isotopes such as 12C, does not show any adverse biological effects even at highest enrichments. The doses of stable isotope tracer substances that are used for clinical diagnostic and research purposes appear safe and without any adverse effects. Stable isotope tracers should only be used in children if the trace is safe at the doses applied, and tracer is chemically pure and stable. In the case of intravenous application, the tracer preparation must also be sterile and pyrogen free.

From Hills to Holes: How Climate Change and Mining are Altering Runoff Processes in Canada

NASA Astrophysics Data System (ADS)

Carey, S. K.

2015-12-01

Canadian environments are under considerable pressure from both climate and land-use change. While warming temperatures are widespread and amplified in the north, surface mining has resulted in large-scale landscape disturbance. How these changes affect catchment response is profound, fundamentally altering the cycling and delivery of water and geochemicals to the drainage network. In permafrost-underlain environments, coupled mass and energy processes control runoff response, and as ground thaw increases, new subsurface pathways become accessible while changing overall catchment storage. With surface mining, watersheds are altered such that they bare little resemblance to what existed prior to mining. In this presentation, data will be presented from long-term experiments exploring the impact of climate and mining on runoff processes in cold catchments using stable isotopes of water and associated hydrometric measurements. In southern Yukon, results from the Wolf Creek Research Basin highlights the influence of surface energy balances on controlling the timing and magnitude of flow response, with inter-annual variability largely driven by how atmospheric forcing interacts with permafrost-underlain areas of the catchment. In mountainous areas of southern British Columbia, surface mining reconfigures landscapes as valleys are filled with waste-rock. Mine-influenced catchments exhibit attenuated flows with delays in spring freshet and a more muted to precipitation. Stable isotopes in stream water suggests that both waste-rock and reference catchments are well mixed, however reference catchments are more responsive to enrichment and depletion events and that mine-influenced catchments had a heavier isotope signature than reference watersheds, suggesting enhanced influence of rainfall on recharge. In both cases, snow storage and release exerts considerable control on streamflow responses, and future changes in streamflow regimes will reflect both a changes in the snow regime and inherent catchment storage properties that are dynamic with time.

Stable isotope analysis of Dacryoconarid carbonate microfossils: a new tool for Devonian oxygen and carbon isotope stratigraphy.

PubMed

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

2015-04-30

Dacryoconarids are extinct marine zooplankton known from abundant, globally distributed calcite microfossils in the Devonian, but their shell stable isotope composition has not been previously explored. Devonian stable isotope stratigraphy is currently limited to less common invertebrates or bulk rock analyses of uncertain provenance. As with Cenozoic planktonic foraminifera, isotopic analysis of dacryoconarid shells could facilitate higher-resolution, geographically widespread stable isotope records of paleoenvironmental change, including marine hypoxia events, climate changes, and biocrises. We explored the use of Dacryoconarid isotope stratigraphy as a viable method in interpreting paleoenvironments. We applied an established method for determining stable isotope ratios (δ(13) C, δ(18) O values) of small carbonate microfossils to very well-preserved dacryoconarid shells. We analyzed individual calcite shells representing five common genera using a Kiel carbonate device coupled to a MAT 253 isotope ratio mass spectrometer. Calcite shell δ(13) C and δ(18) O values were compared by taxonomic group, rock unit, and locality. Single dacryoconarid calcite shells are suitable for stable isotope analysis using a Kiel-IRMS setup. The dacryoconarid shell δ(13) C values (-4.7 to 2.3‰) and δ(18) O values (-10.3 to -4.8‰) were consistent across taxa, independent of shell size or part, but varied systematically through time. Lower fossil δ(18) O values were associated with warmer water temperature and more variable δ(13) C values were associated with major bioevents. Dacryoconarid δ(13) C and δ(18) O values differed from bulk rock carbonate values. Dacryoconarid individual microfossil δ(13) C and δ(18) O values are highly sensitive to paleoenvironmental changes, thus providing a promising avenue for stable isotope chemostratigraphy to better resolve regional to global paleoceanographic changes throughout the upper Silurian to the upper Devonian. Our results warrant further exploration of dacryoconarid stable isotope proxy sensitivity, the isotopic contrast among dacryoconarids, other taxa, and bulk rock, as well as other potential dacryoconarid proxies (Mg/Ca, Sr/Ca, (87) Sr/(86) Sr, microlaser and ion microprobe isotope techniques, and clumped isotopes) for stratigraphic research. Copyright © 2015 John Wiley & Sons, Ltd.

Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes

EPA Science Inventory

In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River Area of Concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abno...

Cosmic ray exposure histories of Apollo 14, Apollo 15, and Apollo 16 rocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eugster, O.; Eberhardt, P.

1984-02-15

The regolith exposure history of six rocks returned by the Apollo 14, 15, and 16 missions is studied based on the cosmogenic noble gas isotopes. For each sample, the complete set of all stable noble gas isotopes and the radiaoctive isotope Kr-81 were measured. Kr-81-Kr exposure ages are calculated for rocks for which a single-stage exposure can be demonstrated. A two-stage model exposure history is derived for multistage-exposure basalt 14310 based on the amounts and isotopic ratios of the cosmogenic noble gases. The apparent Kr-81-Kr age, the depth-sensitive isostopic ratios, and fission Xe-136 results lead to the conclusion that thismore » sample was preexposed 1.75 AE ago to cosmic rays for a duration of 350 m.y. Basalt 15058 and anorthosite 15415 also reveal multistage exposures. 44 references.« less

Metal stable isotopes in weathering and hydrology: Chapter 10

USGS Publications Warehouse

Bullen, Thomas D.; Holland, Heinrich; Turekian, K.

2014-01-01

This chapter highlights some of the major developments in the understanding of the causes of metal stable isotope compositional variability in and isotope fractionation between natural materials and provides numerous examples of how that understanding is providing new insights into weathering and hydrology. At this stage, our knowledge of causes of stable isotope compositional variability among natural materials is greatest for the metals lithium, magnesium, calcium, and iron, the isotopes of which have already provided important information on weathering and hydrological processes. Stable isotope compositional variability for other metals such as strontium, copper, zinc, chromium, barium, molybdenum, mercury, cadmium, and nickel has been demonstrated but is only beginning to be applied to questions related to weathering and hydrology, and several research groups are currently exploring the potential. And then there are other metals such as titanium, vanadium, rhenium, and tungsten that have yet to be explored for variability of stable isotope composition in natural materials, but which may hold untold surprises in their utility. This impressive list of metals having either demonstrated or potential stable isotope signals that could be used to address important unsolved questions related to weathering and hydrology, constitutes a powerful toolbox that will be increasingly utilized in the coming decades.

Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms

NASA Astrophysics Data System (ADS)

Shanks, W. C., III; Böhlke, J. K.; Seal, R. R., II

Studies of abundance variations of light stable isotopes in nature have had a tremendous impact on all aspects of geochemistry since the development, in 1947, of a gas source isotope ratio mass spectrometer capable of measuring small variations in stable isotope ratios [Nier, 1947] Stable isotope geochemistry is now a mature field, as witnessed by the proliferation of commercially available mass spectrometers installed at virtually every major academic, government, and private-sector research geochemistry laboratory. A recent search of a literature database revealed over 3,000 articles that utilized stable isotope geochemistry over the last 20 years. Nonetheless, many exciting new technical developments are leading to exciting new discoveries and applications. In particular, micro analytical techniques involving new generations of laser- and ion-microprobes are revolutionizing the types of analyses that can be done on spot sizes as small as a few tens of micrometers [Shanks and Criss, 1989]. New generations of conventional gas source and thermal ionization mass spectrometers, with high levels of automation and increased sensitivity and precision, are allowing analyses of large numbers of samples, like those needed for stable isotope stratigraphy in marine sediments, and are enabling the development and application of new isotopic systems.

Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms

USGS Publications Warehouse

Shanks, Wayne C.; Böhlke, John Karl; Seal, Robert R.; Humphries, S.D.; Zierenberg, Robert A.; Mullineaux, Lauren S.; Thomson, Richard E.

1995-01-01

Studies of abundance variations of light stable isotopes in nature have had a tremendous impact on all aspects of geochemistry since the development, in 1947, of a gas source isotope ratio mass spectrometer capable of measuring small variations in stable isotope ratios (Nice, 1947]. Stable isotope geochemistry is now a mature field, as witnessed by the proliferation of commercially available mass spectrometers installed at virtually every major academic, government, and private-sector research geochemistry laboratory. A recent search of a literature database revealed over 3,000 articles that utilized stable isotope geochemistry over the last 20 years. Nonetheless, many exciting new technical developments are leading to exciting new discoveries and applications. In particular, micro-analytical techniques involving new generations of laser- and ion-microprobes are revolutionizing the types of analyses that can be done on spot sizes as small as a few tens of micrometers [Shanks and Criss, 1989]. New generations of conventional gas source and thermal ionization mass spectrometers, with high levels of automation and increased sensitivity and precision, are allowing analyses of large numbers of samples, like those needed for stable isotope stratigraphy in marine sediments, and are enabling the development and application of new isotopic systems.

Applications of stable isotope analysis in mammalian ecology.

PubMed

Walter, W David; Kurle, Carolyn M; Hopkins, John B

2014-01-01

In this editorial, we provide a brief introduction and summarize the 10 research articles included in this Special Issue on Applications of stable isotope analysis in mammalian ecology. The first three articles report correction and discrimination factors that can be used to more accurately estimate the diets of extinct and extant mammals using stable isotope analysis. The remaining seven applied research articles use stable isotope analysis to address a variety of wildlife conservation and management questions from the oceans to the mountains.

Stable isotope methodology in the pharmacokinetic studies of androgenic steroids in humans.

PubMed

Shinohara, Y; Baba, S

1990-04-01

The use of stable isotopically labeled steroids combined with gas chromatography/mass spectrometry (GC/MS) has found a broad application in pharmacologic studies. Initially, stable isotopically labeled steroids served as the ideal analytic internal standard for GC/MS analysis; however, their in vivo use has expanded and has proven to be a powerful pharmacokinetic tool. We have successfully used stable isotope methodology to study the pharmacokinetic/bioavailability of androgens. The primary advantage of the technique is that endogenous and exogenous steroids with the same basic structure can be differentiated by using stable isotopically labeled analogs. The method was used to examine the pharmacokinetics of testosterone and testosterone propionate, and to clarify the influence of endogenous testosterone. Another advantage of the isotope methods is that steroidal drugs can be administered concomitantly in two formulations (e.g., solution and solid dosage). A single set of blood samples serves to describe the time course of the formulations being compared. This stable isotope coadministration technique was used to estimate the relative bioavailability of 17 alpha-methyltestosterone.

Illuminating hydrological processes at the soil-vegetation-atmosphere interface with water stable isotopes

NASA Astrophysics Data System (ADS)

Sprenger, Matthias; Leistert, Hannes; Gimbel, Katharina; Weiler, Markus

2016-09-01

Water stable isotopes (18O and 2H) are widely used as ideal tracers to track water through the soil and to separate evaporation from transpiration. Due to the technical developments in the last two decades, soil water stable isotope data have become easier to collect. Thus, the application of isotope methods in soils is growing rapidly. Studies that make use of soil water stable isotopes often have a multidisciplinary character since an interplay of processes that take place in the vadose zone has to be considered. In this review, we provide an overview of the hydrological processes that alter the soil water stable isotopic composition and present studies utilizing pore water stable isotopes. The processes that are discussed include the water input as precipitation or throughfall, the output as evaporation, transpiration, or recharge, and specific flow and transport processes. Based on the review and supported by additional data and modeling results, we pose a different view on the recently proposed two water world hypothesis. As an alternative to two distinct pools of soil water, where one pool is enriched in heavy isotopes and used by the vegetation and the other pool does not undergo isotopic fractionation and becomes recharge, the water gets successively mixed with newly introduced rainwater during the percolation process. This way, water initially isotopically enriched in the topsoil loses the fractionation signal with increasing infiltration depth, leading to unfractionated isotopic signals in the groundwater.

Use of stable isotope analysis in determining aquatic food webs

EPA Science Inventory

Stable isotope analysis is a useful tool for describing resource-consumer dynamics in ecosystems. In general, organisms of a given trophic level or functional feeding group will have a stable isotope ratio identifiable different than their prey because of preferential use of one ...

Water stable isotope shifts of surface waters as proxies to quantify evaporation, transpiration and carbon uptake on catchment scales

NASA Astrophysics Data System (ADS)

Barth, Johannes; van Geldern, Robert; Veizer, Jan; Karim, Ajaz; Freitag, Heiko; Fowlwer, Hayley

2017-04-01

Comparison of water stable isotopes of rivers to those of precipitation enables separation of evaporation from transpiration on the catchment scale. The method exploits isotope ratio changes that are caused exclusively by evaporation over longer time periods of at least one hydrological year. When interception is quantified by mapping plant types in catchments, the amount of water lost by transpiration can be determined. When in turn pairing transpiration with the water use efficiency (WUE i.e. water loss by transpiration per uptake of CO2) and subtracting heterotrophic soil respiration fluxes (Rh), catchment-wide carbon balances can be established. This method was applied to several regions including the Great Lakes and the Clyde River Catchments ...(Barth, et al., 2007, Karim, et al., 2008). In these studies evaporation loss was 24 % and 1.3 % and transpiration loss was 47 % and 22 % when compared to incoming precipitation for the Great Lakes and the Clyde Catchment, respectively. Applying WUE values for typical plant covers and using area-typical Rh values led to estimates of CO2 uptake of 251 g C m-2 a-1 for the Great Lakes Catchment and CO2 loss of 21 g C m2 a-1 for the Clyde Catchment. These discrepancies are most likely due to different vegetation covers. The method applies to scales of several thousand km2 and has good potential for improvement via calibration on smaller scales. This can for instance be achieved by separate treatment of sub-catchments with more detailed mapping of interception as a major unknown. These previous studies have shown that better uncertainty analyses are necessary in order to estimate errors in water and carbon balances. The stable isotope method is also a good basis for comparison to other landscape carbon balances for instance by eddy covariance techniques. This independent method and its up-scaling combined with the stable isotope and area-integrating methods can provide cross validation of large-scale carbon budgets. Together they can help to constrain relationships between carbon and water balances on the continental scale. References .Barth JAC, Freitag H, Fowler HJ, Smith A, Ingle C, Karim A (2007) Water fluxes and their control on the terrestrial carbon balance: Results from a stable isotope study on the Clyde Watershed (Scotland). Appl Geochem 22: 2684-2694 DOI 10.1016/j.apgeochem.2007.06.002 Karim A, Veizer J, Barth J.A.C. (2008) Net ecosystem production in the great lakes basin and its implications for the North American missing carbon sink: A hydrologic and stable isotope approach. Global and Planetary Change 61: 15-27 DOI 10.1016/j.gloplacha.2007.08.004

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

USDA-ARS?s Scientific Manuscript database

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...

Carbonic Anhydrase, Calcification Dynamics and Stable Isotope Vital Effects: Deep Sea Corals and Beyond

NASA Astrophysics Data System (ADS)

Chen, S.; Gagnon, A. C.; Adkins, J. F.

2017-12-01

The stable isotope compositions of biogenic carbonates have been used for paleoceanographic and paleoclimatic reconstructions for decades, and produced some of the most iconic records in the field. However, we still lack a fully mechanistic understanding of the stable isotope proxies, especially the biological overprint on the environmental signals termed "vital effects". A ubiquitous feature of stable isotope vital effects in marine calcifying organisms is a strong correlation between δ18O and δ13C in a range of values that are depleted from equilibrium. Two mechanisms have been proposed to explain this correlation, one based on kinetic isotope effects during CO2(aq)-HCO3- inter-conversion, the other based on equilibrium isotope exchange during pH dependent speciation of the dissolved inorganic carbon pool. Neither mechanism explains all the stable isotope features observed in biogenic carbonates. Here we present a fully kinetic model of biomineralization and its isotope effects using deep sea corals as a test organism. A key component of our model is the consideration of the enzyme carbonic anhydrase in catalyzing the CO2(aq)-HCO3- inter-conversion reactions in the extracellular calcifying fluid (ECF). We find that the amount of carbonic anhydrase not only modulates the carbonate chemistry of the calcifying fluid, but also helps explain the slope of the δ18O-δ13C correlation. With this model, we are not only able to fit deep sea coral data, but also explain the stable isotope vital effects of other calcifying organisms. This fully kinetic model of stable isotope vital effects and the underlying calcification dynamics may also help us better understand mechanisms of other paleoceanographic tracers in biogenic carbonates, including boron isotopes and trace metal proxies.

Astronaut Bones: Stable Calcium Isotopes in Urine as a Biomarker of Bone Mineral Balance

NASA Astrophysics Data System (ADS)

Skulan, J.; Gordon, G. W.; Romaniello, S. J.; Anbar, A. D.; Smith, S. M.; Zwart, S.

2016-12-01

Bone loss is a common health concern, in conditions ranging from osteoporosis to cancer. Bone loss due to unloading is also an important health issue for astronauts. We demonstrate stable calcium isotopes, a tool developed in geochemistry, are capable of detecting real-time quantitative changes in net bone mineral balance (BMB) using serum and urine [1]. We validated this technique by comparing with DEXA and biomarker data in subjects during bed rest, a ground-based analog of space flight effects [2-4]. We now apply this tool to assess changes in astronauts' BMB before, during and after 4-6 month space missions. There is stable isotope fractionation asymmetry between bone formation and resorption. During bone formation there is a mass-dependent preference for "lighter" calcium isotopes to be removed from serum and incorporated into bone mineral. During bone resorption, there is no measurable isotopic discrimination between serum and bone. Hence, when bone formation rates exceed that of resorption, serum and urine become isotopically "heavy" due to the sequestration of "light" calcium in bone. Conversely, when bone resorption exceeds bone formation, serum and urine become isotopically "light" due to the release of the sequestered light calcium from bone. We measured Ca isotopes in urine of thirty International Space Station astronauts. Average Ca isotope values in astronauts' urine shift isotopically lighter during microgravity, consistent with negative net BMB. Within a month of return to Earth, astronauts returned to within error of their δ44Ca value prior to departure. Urine samples from astronauts testing bone loss countermeasures showed bisphosphonates provide a viable pharmacological countermeasure. Some, but not all, individuals appear able to resist bone loss through diet and intensive resistive exercise alone. This is a promising new technique for monitoring BMB in astronauts, and hopefully someday on the way to/from Mars, this also has important clinical applications for human health and terrestrial medicine [5]. REFERENCES [1] Morgan, J.L. et al (2011) Anal Chem 83, 6956-6962. [2] Skulan, J.L. et al. (2007) Clin Chem 53, 1155-1158. [3] Morgan, J.L. et al (2012) PNAS 109, 9989-9994. [4] Channon, M.B. et al (2015) Bone 77, 69-74. [5] Gordon, G.W. et al (2014) Leukemia 28, 2112-2115.

Defining a stable water isotope framework for isotope hydrology application in a large trans-boundary watershed (Russian Federation/Ukraine).

PubMed

Vystavna, Yuliya; Diadin, Dmytro; Huneau, Frédéric

2018-05-01

Stable isotopes of hydrogen ( 2 H) and oxygen ( 18 O) of the water molecule were used to assess the relationship between precipitation, surface water and groundwater in a large Russia/Ukraine trans-boundary river basin. Precipitation was sampled from November 2013 to February 2015, and surface water and groundwater were sampled during high and low flow in 2014. A local meteoric water line was defined for the Ukrainian part of the basin. The isotopic seasonality in precipitation was evident with depletion in heavy isotopes in November-March and an enrichment in April-October, indicating continental and temperature effects. Surface water was enriched in stable water isotopes from upstream to downstream sites due to progressive evaporation. Stable water isotopes in groundwater indicated that recharge occurs mainly during winter and spring. A one-year data set is probably not sufficient to report the seasonality of groundwater recharge, but this survey can be used to identify the stable water isotopes framework in a weakly gauged basin for further hydrological and geochemical studies.

Arthropod food web restoration following removal of an invasive wetland plant.

PubMed

Gratton, Claudio; Denno, Robert F

2006-04-01

Restoration of habitats impacted by invasive plants is becoming an increasingly important tool in the management of native biodiversity, though most studies do not go beyond monitoring the abundance of particular taxonomic groups, such as the return of native vegetation. Yet, the reestablishment of trophic interactions among organisms in restored habitats is equally important if we are to monitor and understand how ecosystems recover. This study examined whether food web interactions among arthropods (as inferred by abundance of naturally occurring stable isotopes of C [delta13C] and N [delta15N]) were reestablished in the restoration of a coastal Spartina alterniflora salt marsh that had been invaded by Phragmites australis. From patterns of C and N stable isotopes we infer that trophic interactions among arthropods in the native salt marsh habitats are characterized by reliance on the dominant marsh plant Spartina as a basal resource. Herbivores such as delphacid planthoppers and mirid bugs have isotope signatures characteristic of Spartina, and predatory arthropods such as dolicopodid flies and spiders likewise have delta13C and delta15N signatures typical of Spartina-derived resources (approximately -13 per thousand and 10 per thousand, respectively). Stable isotope patterns also suggest that the invasion of Phragmites into salt marshes and displacement of Spartina significantly alter arthropod food web interactions. Arthropods in Phragmites-dominated sites have delta13C isotope values between -18 per thousand and -20 per thousand, suggesting reliance on detritus and/or benthic microalgae as basal resources and not on Phragmites, which has a delta13C approximately -26 per thousand. Since most Phragmites herbivores are either feeding internally or are rare transients from nearby Spartina, these resources do not provide significant prey resources for other arthropod consumers. Rather, predator isotope signatures in the invaded habitats indicate dependence on detritus/algae as basal resources instead of the dominant vegetation. The reestablishment of Spartina after removal of Phragmites, however, not only returned species assemblages typical of reference (uninvaded) Spartina, but stable isotope signatures suggest that the trophic interactions among the arthropods were also similar in reestablished habitats. Specifically, both herbivores and predators showed characteristic Spartina signatures, suggesting the return of the original grazer-based food web structure in the restored habitats.

Osmium Stable Isotope Composition of Chondrites and Iron Meteorites: Implications for Planetary Core Formation

NASA Astrophysics Data System (ADS)

Nanne, J. A. M.; Millet, M. A.; Burton, K. W.; Dale, C. W.; Nowell, G. M.; Williams, H. M.

2016-12-01

Mass-dependent Os stable isotope fractionation is expected to occur during metal-silicate segregation as well as during crystallization of metal alloys due to the different bonding environment between silicate and metals. As such, Os stable isotopes have the potential to resolve questions pertaining to planetary accretion and differentiation. Here, we present stable Os isotope data for a set of chondrites and iron meteorites to examine the processes associated with core solidification. Carbonaceous, ordinary, and enstatite chondrites show no detectable stable isotope variation with a δ190Os weighted average of +0.12±0.04 (n=37). The uniform composition observed for chondrites implies Os stable isotope homogeneity of the bulk solar nebula. Contrary to chondrites, iron meteorites display a large range in Os stable isotope compositions from δ190Os of +0.05 up to +0.49‰. Variation is only observed in the IIAB and IIIAB irons. Type IVB irons display values similar to chondrites (+0.107±0.047 [n=3]) and IVA compositions are slightly different +0.187±0.004 (n=2). The type IIAB and IIIAB groups show values both within the chondritic range and up to heavier values extending up to +0.49‰. Since core formation in small planetary bodies is expected to quantitatively sequester Os in metal phases, bulk planetary cores are expected to display chondritic δ190Os values. Conversely, samples of the IIAB and IIIAB group display significant variation, possibly indicating that stable isotope fractionation occurred during solidification of the parent-body core. However, no covariation is observed between δ190Os and either Os abundance or radiogenic Os isotope ratios. Instead, liquid immiscibility during core crystallization, where the liquid metal splits into separate S- and P-rich liquids, may be a source of Os stable isotope fractionation.

Stable-isotope customer list and summary of shipments, FY 1982

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, W.C.

1983-04-01

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

Stable isotope quality assurance using the 'calibrated IRMS' strategy.

PubMed

Meijer, Harro A J

2009-06-01

Procedures in our laboratory have always been directed towards complete understanding of all processes involved and corrections needed etc., instead of relying fully on laboratory reference materials. This rather principal strategy (or attitude) is probably not optimal in the economic sense, and is not necessarily more accurate either. Still, it has proven to be very rewarding in its capability to detect caveats that go undiscovered in the standard way of measurement, but that do influence the accuracy or reliability of the measurement procedure. An additional benefit of our laboratory procedures is that it makes us capable of assisting the International Atomic Energy Agency (IAEA) with primary questions like mutual scale assignments and comparison of isotope ratios of the same isotope in different matrices (like delta(18)O in water, carbonates and atmospheric CO(2)), establishment of the (17)O-(18)O relation, and the replenishment of the calibration standards. Finally, for manual preparation systems with a low sample throughput (and thus only few reference materials analysed) it may well be the only way to produce reliable results.

Stable isotope analysis of larval mosquito diets in agricultural wetlands in the coastal plain of Georgia, U.S.A.

PubMed

Young, Gina Botello; Golladay, Stephen; Covich, Alan; Blackmore, Mark

2014-12-01

Previous studies have used C and N isotope ratios to investigate the use of different food resources such as plant and animal detritus by container-breeding mosquitoes. This study is the first to report on the potential food resources assimilated by larval mosquitoes in agricultural and reference wetlands. Larval mosquitoes (Diptera: Culcidae) were sampled, along with their potential food resources, from agricultural and reference wetland habitats throughout a seasonal hydroperiod. IsoSource mixing model results indicated that food resources had greater δ(15) N isotope values in agricultural wetlands compared with cypress-gum swamps. In February, Aedes vexans (Meigen) and Culex territans Walker larvae fed primarily on lower quality food resources (coarse particulate organic matter and sediment) based on C:N. In contrast, higher quality food resources (fine particulate organic matter) were utilized by Anopheles spp. throughout the study and by Psorophora columbiae (Dyer and Knab) in May. This research contributes to a more comprehensive understanding of the food resources available and assimilated by larval mosquitoes in agricultural wetlands. © 2014 The Society for Vector Ecology.

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...

IsoBank – Stable isotope ecology in the age of ‘Big Data’

USDA-ARS?s Scientific Manuscript database

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

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

EPA Science Inventory

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

Environmental and biomedical applications of natural metal stable isotope variations

USGS Publications Warehouse

Bullen, T.D.; Walczyk, T.

2009-01-01

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

Can We Untangle the Weather? Stable Water Isotope Controls on the Juneau Icefield

NASA Astrophysics Data System (ADS)

Ihle, A. C.; Keenan, E.; Yong, C.; Bridgers, S. L.; Markle, B. R.; Hamel, J.; Klein, E. S.

2017-12-01

Stable water isotopes in snow and ice provide a reliable proxy for past weather and climate. However, untangling weather and climate signals from water isotopes on the Juneau Icefield, Alaska, has proven difficult due to consistent summer melt and rain. The Juneau Icefield is a large glaciated region consisting of complex terrain and sharp climatic gradients. Here we study how topographic steepness and elevation influence stable water isotope ratios on the Juneau Icefield using vertical snowpit profiles collected from water year 2017's snowpack. As terrain steepens, we expect gradients in isotope ratios to intensify. In addition, we aim to determine how post-depositional metamorphism, particularly precipitation, affects water isotope ratios. We anticipate rain events to increase the proportion of heavy water isotopes. Lastly, we compare model output and remote sensing observations of storm origin to vertical stratigraphy of stable isotope ratios in the snowpack in order to determine if it is possible to use isotopes to identify past storm tracks on the Juneau Icefield. Snowpack isotope stratigraphy ratios can likely be linked to seasonal trends of storm characteristics. Given this enhanced understanding of how stable water isotopes behave on the Juneau Icefield, we contribute to the understanding of past weather and climate, both here and elsewhere, and explore the possibility for future deep ice cores on the Juneau Icefield.

Our Hidden Past: Peacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Ray

Y-12 separated isotopes to win the war, then during the 1950s separated isotopes to save lives. Y-12's calutrons were used for a peacetime mission in the stable isotope program. Y-12 provided stable isotopes for research in medicine, agriculture, industry and biology.

Our Hidden Past: Peacetime

ScienceCinema

Smith, Ray

2018-06-04

Y-12 separated isotopes to win the war, then during the 1950s separated isotopes to save lives. Y-12's calutrons were used for a peacetime mission in the stable isotope program. Y-12 provided stable isotopes for research in medicine, agriculture, industry and biology.

In Situ measurement of Kr and Xe in the atmosphere of Mars

NASA Astrophysics Data System (ADS)

Conrad, P. G.; Malespin, C.; Franz, H. B.; Trainer, M. G.; Pepin, R. O.; Schwenzer, S. P.; Manning, H. L.; Atreya, S. K.; Wong, M. H.; Jones, J. H.; Owen, T. C.; Mahaffy, P. R.

2015-12-01

Abstract: The Sample Analysis at Mars (SAM) investigation [1] on NASA's Mars Science Laboratory mission has measured the six stable isotopes of krypton and the nine stable isotopes of xenon from the surface of Mars. Using semi-static mass spectrometry (MS) to measure the Kr, and static MS experiments (first ever on another planet) to measure the xenon, we have obtained isotopic ratios of these heavy noble gas elements with greatly improved precision over the Viking Measurements. The Viking landers detected both Kr and Xe [2] with a reported precision of ±20%, insufficient for in situ isotope measurement. Using the Viking observation of high 129Xe relative to Earth or to solar wind, Bogard & Johnson [3] and Swindle et al. [4] recognized that Shergottite meteorites may hold trapped Martian atmosphere, from which Swindle's team later reported precise noble gas isotope ratios, solidifying the theory that these meteorites were of martian origin. Our data are in very good agreement with the Swindle et al. [4] analysis, and the isotopic distributions of Kr and Xe in present day Martian atmosphere support the Pepin [5] model of massive hydrodynamic escape of the martian atmosphere early after formation. References: [1] Mahaffy, Paul R., et al. Space Science Revs 170.1-4 (2012): 401-478. [2] Owen, T., et al. Science 194.4271 (1976): 1293-1295. [3] Bogard, D. D. & Johnson, P. (1983) Science, 221: 651-654. [4] Swindle, T. D., M. W. Caffee, and C. M. Hohenberg. Geochim et Cosmochim Acta 50.6 (1986): 1001-1015. [5] Pepin, Robert O. Icarus 111.2 (1994): 289-304.

Provenancing Archaeological Wool Textiles from Medieval Northern Europe by Light Stable Isotope Analysis (δ13C, δ15N, δ2H)

PubMed Central

von Holstein, Isabella C. C.; Walton Rogers, Penelope; Craig, Oliver E.; Penkman, Kirsty E. H.; Newton, Jason; Collins, Matthew J.

2016-01-01

We investigate the origin of archaeological wool textiles preserved by anoxic waterlogging from seven medieval archaeological deposits in north-western Europe (c. 700–1600 AD), using geospatial patterning in carbon (δ13C), nitrogen (δ15N) and non-exchangeable hydrogen (δ2H) composition of modern and ancient sheep proteins. δ13C, δ15N and δ2H values from archaeological wool keratin (n = 83) and bone collagen (n = 59) from four sites were interpreted with reference to the composition of modern sheep wool from the same regions. The isotopic composition of wool and bone collagen samples clustered strongly by settlement; inter-regional relationships were largely parallel in modern and ancient samples, though landscape change was also significant. Degradation in archaeological wool samples, examined by elemental and amino acid composition, was greater in samples from Iceland (Reykholt) than in samples from north-east England (York, Newcastle) or northern Germany (Hessens). A nominal assignment approach was used to classify textiles into local/non-local at each site, based on maximal estimates of isotopic variability in modern sheep wool. Light element stable isotope analysis provided new insights into the origins of wool textiles, and demonstrates that isotopic provenancing of keratin preserved in anoxic waterlogged contexts is feasible. We also demonstrate the utility of δ2H analysis to understand the location of origin of archaeological protein samples. PMID:27764106

Investigating differences in light stable isotopes between Thai jasmine rice and Sungyod rice

NASA Astrophysics Data System (ADS)

Kukusamude, C.; Kongsri, S.

2017-10-01

We report the differences in light stable isotopes between two kinds of Thai rice (Thai jasmine and Sungyod rice). Thai jasmine rice and Sungyod rice were cultivated in the northeast and the south of Thailand. Light isotopes including 13C, 15N and 18O of Thai jasmine rice and Sungyod rice samples were carried out using isotope ratio mass spectrometry (IRMS). Thai jasmine rice (Khao Dawk Mali 105) was cultivated from Thung Kula Rong Hai area, whereas Sungyod rice was cultivated from Phathalung province. Hypothesis testing of difference of each isotope between Thai jasmine rice and Sungyod rice was also studied. The study was the feasibility test whether the light stable isotopes can be the variables to identify Thai jasmine rice and Sungyod rice. The result shows that there was difference in the isotope patterns of Thai jasmine rice and Sungyod rice. Our results may provide the useful information in term of stable isotope profiles of Thai rice.

Stable Isotope Identification of Nitrogen Sources for United States (U.S.) Pacific Coast Estuaries

EPA Science Inventory

We used natural abundance stable isotope data to evaluate nitrogen sources to U.S. west coast estuaries. We collected δ15N of macroalgae data and supplemented this with available data from the literature for estuaries from Mexico to Alaska. Stable isotope ratios of green m...

A free-air system for long-term stable carbon isotope labeling of adult forest trees

EPA Science Inventory

Stable carbon (C) isotopes, in particular employed in labeling experiments, are an ideal tool to broaden our understanding of C dynamics in trees and forest ecosystems. Here, we present a free-air exposure system, named isoFACE, designed for long-term stable C isotope labeling in...

Using Stable Isotopes to Assess Connectivity: the Importance of Oceanic and Watershed Nitrogen Sources for Estuarine Primary Producers

EPA Science Inventory

Estuaries located at the interface of terrestrial and oceanic ecosystems receive nutrients from both ecosystems. Stable isotopes of primary producers and consumers are often used as an indicator of nutrient sources. We assembled natural abundance nitrogen stable isotope (δ15N) d...

Stable Isotope Applications for Understanding Shark Ecology in the Northeast Pacific Ocean.

PubMed

Reum, Jonathan C P; Williams, Gregory D; Harvey, Chris J

Stable isotopes are used to address a wide range of ecological questions and can help researchers and managers better understand the movement and trophic ecology of sharks. Here, we review how shark studies from the Northeast Pacific Ocean (NEP) have employed stable isotopes to estimate trophic level and diet composition and infer movement and habitat-use patterns. To date, the number of NEP shark studies that have used stable isotopes is limited, suggesting that the approach is underutilized. To aid shark researchers in understanding the strengths and limitations of the approach, we provide a brief overview of carbon and nitrogen stable isotope trophic discrimination properties (e.g., change in δ 15 N between predator and prey), tissue sample preparation methods specific to elasmobranchs, and methodological considerations for the estimation of trophic level and diet composition. We suggest that stable isotopes are a potentially powerful tool for addressing basic questions about shark ecology and are perhaps most valuable when combined and analysed with other data types (e.g., stomach contents, tagging data, or other intrinsic biogeochemical markers). © 2017 Elsevier Ltd. All rights reserved.

Experimental investigation of concentration and stable isotopes signals during organic contaminants back diffusion

NASA Astrophysics Data System (ADS)

Jin, Biao; Nika, Chrysanthi-Elisabeth; Rolle, Massimo

2017-04-01

Back diffusion of organic contaminants is often the cause of groundwater plumes' persistence and can significantly hinder cleanup interventions [1, 2]. In this study we perform a high-resolution investigation of back diffusion in a well-controlled flow-through laboratory setup. We considered cis-dichloroethene (cis-DCE) as model contaminant and we investigated its back diffusion from an impermeable source into a permeable saturated layer, in which advection-dominated flow conditions were established. We used concentration and stable chlorine isotope measurements to investigate the plumes originated by cis-DCE back diffusion in a series of flow-through experiments, performed in porous media with different hydraulic conductivity and at different seepage velocities (i.e., 0.4, 0.8 and 1.2 m/day). A two-centimeter thick agarose gel layer was placed at the bottom of the setup to simulate the source of cis-DCE back diffusion from an impervious layer. Intensive sampling (>1000 measurements) was carried out, including the withdrawal of aqueous samples at closely spaced (1 cm) outlet ports, as well as the high-resolution sampling of the source zone (agarose gel) at the end of each experiment. The transient behavior of the plumes originated by back diffusion was investigated by sampling the outlet ports at regular intervals in the experiments, each run for a total time corresponding to 15 pore volumes. The high-resolution sampling allowed us to resolve the spatial and temporal evolution of concentration and stable isotope gradients in the flow-through setup. In particular, steep concentration and stable isotope gradients were observed at the outlet. Lateral isotope gradients corresponding to chlorine isotope fractionation up to 20‰ were induced by cis-DCE back diffusion and subsequent advection-dominated transport in all flow-through experiments. A numerical modeling approach, tracking individually all chlorine isotopologues, based on the accurate parameterization of local dispersion, as well as on the values of aqueous diffusion coefficients and diffusion-induced isotope fractionation from a previous study [3], provided a good agreement with the experimental data. References [1] Mackay, D. M.; Cherry, J. A. Groundwater contamination: Pumpand-treat remediation. Environ. Sci. Technol. 1989, 23, 630-636. [2] Parker, B. L.; Chapman, S. W.; Guilbeault, M. A. Plume persistence caused by back diffusion from thin clay layers in a sand aquifer following TCE source-zone hydraulic isolation. J. Contam. Hydrol. 2008, 102, 19-19. [3] Jin, B., Rolle, M., Li, T., Haderlein, S.B., 2014. Diffusive fractionation of BTEX and chlorinated ethenes in aqueous solution: quantification of spatial isotope gradients. Environ. Sci. Technol. 48, 6141-6150.

Stable isotope labeling by essential nutrients in cell culture for preparation of labeled coenzyme A and its thioesters.

PubMed

Basu, Sankha S; Mesaros, Clementina; Gelhaus, Stacy L; Blair, Ian A

2011-02-15

Stable isotope dilution mass spectrometry (MS) represents the gold standard for quantification of endogenously formed cellular metabolites. Although coenzyme A (CoA) and acyl-CoA thioester derivatives are central players in numerous metabolic pathways, the lack of a commercially available isotopically labeled CoA limits the development of rigorous MS-based methods. In this study, we adapted stable isotope labeling by amino acids in cell culture (SILAC) methodology to biosynthetically generate stable isotope labeled CoA and thioester analogues for use as internal standards in liquid chromatography/multiple reaction monitoring mass spectrometry (LC/MRM-MS) assays. This was accomplished by incubating murine hepatocytes (Hepa 1c1c7) in media in which pantothenate (a precursor of CoA) was replaced with [(13)C(3)(15)N(1)]-pantothenate. Efficient incorporation into various CoA species was optimized to >99% [(13)C(3)(15)N(1)]-pantothenate after three passages of the murine cells in culture. Charcoal-dextran-stripped fetal bovine serum (FBS) was found to be more efficient for serum supplementation than dialyzed or undialyzed FBS, due to lower contaminating unlabeled pantothenate content. Stable isotope labeled CoA species were extracted and utilized as internal standards for CoA thioester analysis in cell culture models. This methodology of stable isotope labeling by essential nutrients in cell culture (SILEC) can serve as a paradigm for using vitamins and other essential nutrients to generate stable isotope standards that cannot be readily synthesized.

Calcium Isotope Analysis by Mass Spectrometry

NASA Astrophysics Data System (ADS)

Boulyga, S.; Richter, S.

2010-12-01

The variations in the isotopic composition of calcium caused by fractionation in heterogeneous systems and by nuclear reactions can provide insight into numerous biological, geological, and cosmic processes, and therefore isotopic analysis finds a wide spectrum of applications in cosmo- and geochemistry, paleoclimatic, nutritional, and biomedical studies. The measurement of calcium isotopic abundances in natural samples has challenged the analysts for more than three decades. Practically all Ca isotopes suffer from significant isobaric interferences, whereas low-abundant isotopes can be particularly affected by neighboring major isotopes. The extent of natural variations of stable isotopes appears to be relatively limited, and highly precise techniques are required to resolve isotopic effects. Isotope fractionation during sample preparation and measurements and instrumental mass bias can significantly exceed small isotope abundance variations in samples, which have to be investigated. Not surprisingly, a TIMS procedure developed by Russell et al. (Russell et al., 1978. Geochim Cosmochim Acta 42: 1075-1090) for Ca isotope measurements was considered as revolutionary for isotopic measurements in general, and that approach is used nowadays (with small modifications) for practically all isotopic systems and with different mass spectrometric techniques. Nevertheless, despite several decades of calcium research and corresponding development of mass spectrometers, the available precision and accuracy is still not always sufficient to achieve the challenging goals. This presentation discusses figures of merits of presently used analytical methods and instrumentation, and attempts to critically assess their limitations. Additionally, the availability of Ca isotope reference materials will be discussed.

Tracing lead pollution sources in abandoned mine areas using stable Pb isotope ratios.

PubMed

Yoo, Eun-Jin; Lee, Jung-A; Park, Jae-Seon; Lee, Khanghyun; Lee, Won-Seok; Han, Jin-Seok; Choi, Jong-Woo

2014-02-01

This study focused on Pb isotope ratios of sediments in areas around an abandoned mine to determine if the ratios can be used as a source tracer. For pretreatment, sediment samples were dissolved with mixed acids, and a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS, Nu plasma II) was used to investigate the Pb isotopic composition of the samples. The measured isotope ratios were then corrected for instrumental mass fractionation by measuring the (203)Tl/(205)Tl ratio. Repeated measurements with the NIST SRM 981 reference material showed that the precision of all ratios was below 104 ppm (±2σ) for 50 ng/g. The isotope ratios ((207)Pb/(206)Pb) found were 0.85073 ± 0.0004~0.85373 ± 0.0003 for the main stream, while they were 0.83736 ± 0.0010 for the tributary and 0.84393 ± 0.0002 for the confluence. A binary mixing equation for isotope ratios showed that the contributions of mine lead to neighboring areas were up to 60%. Therefore, Pb isotope ratios can be a good source tracer for areas around abandoned mines.

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

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

NASA Astrophysics Data System (ADS)

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

2016-05-01

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

INCORPORATING CONCENTRATION DEPENDENCE IN STABLE ISOTOPE MIXING MODELS

EPA Science Inventory

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

INCORPORATING CONCENTRATION DEPENDENCE IN STABLE ISOTOPE MIXING MODELS

EPA Science Inventory

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

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.

Advances in the Metrology of Absolute Value Assignments to Isotopic Reference Materials: Consequences from the Avogadro Project

NASA Astrophysics Data System (ADS)

Vocke, Robert; Rabb, Savelas

2015-04-01

All isotope amount ratios (hereafter referred to as isotope ratios) produced and measured on any mass spectrometer are biased. This unfortunate situation results mainly from the physical processes in the source area where ions are produced. Because the ionized atoms in poly-isotopic elements have different masses, such processes are typically mass dependent and lead to what is commonly referred to as mass fractionation (for thermal ionization and electron impact sources) and mass bias (for inductively coupled plasma sources.) This biasing process produces a measured isotope ratio that is either larger or smaller than the "true" ratio in the sample. This has led to the development of numerous fractionation "laws" that seek to correct for these effects, many of which are not based on the physical processes giving rise to the biases. The search for tighter and reproducible precisions has led to two isotope ratio measurement systems that exist side-by-side. One still seeks to measure "absolute" isotope ratios while the other utilizes an artifact based measurement system called a delta-scale. The common element between these two measurement systems is the utilization of isotope reference materials (iRMs). These iRMs are used to validate a fractionation "law" in the former case and function as a scale anchor in the latter. Many value assignments of iRMs are based on "best measurements" by the original groups producing the reference material, a not entirely satisfactory approach. Other iRMs, with absolute isotope ratio values, have been produced by calibrated measurements following the Atomic Weight approach (AW) pioneered by NBS nearly 50 years ago. Unfortunately, the AW is not capable of calibrating the new generation of iRMs to sufficient precision. So how do we get iRMs with isotope ratios of sufficient precision and without bias? Such a focus is not to denigrate the extremely precise delta-scale measurements presently being made on non-traditional and tradition stable isotope systems. But even absolute isotope ratio measurements have an important role to play in delta-scale schemes. Highly precise and unbiased measurements of the artifact anchor for any scale facilitates the replacement of that scale's anchor once the initial supply of the iRM is exhausted. Absolute isotope ratio measurements of artifacts at the positive and negative extremes of a delta-scale will allow the appropriate assignment of delta-values to these normalizing iRMs, thereby minimizing any scale contractions or expansions to either side of the anchor artifact. And finally, absolute values for critical iRMs with also allow delta-scale results to be used in other scientific disciplines that employ other units of measure. Precise absolute isotope ratios of Si has been one of the consequences of the Avogadro Project (an international effort to replace the original kilogram artifact with a natural constant, the Planck constant.) We will present the results of applying such measurements to the principal iRMs for the Si isotope system (SRM 990, Big Batch and Diatomite) and its consequences for their delta-Si29 and delta-Si30 values.

Metal Stable Isotope Tagging: Renaissance of Radioimmunoassay for Multiplex and Absolute Quantification of Biomolecules.

PubMed

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

2016-05-17

The unambiguous quantification of biomolecules is of great significance in fundamental biological research as well as practical clinical diagnosis. Due to the lack of a detectable moiety, the direct and highly sensitive quantification of biomolecules is often a "mission impossible". Consequently, tagging strategies to introduce detectable moieties for labeling target biomolecules were invented, which had a long and significant impact on studies of biomolecules in the past decades. For instance, immunoassays have been developed with radioisotope tagging by Yalow and Berson in the late 1950s. The later languishment of this technology can be almost exclusively ascribed to the use of radioactive isotopes, which led to the development of nonradioactive tagging strategy-based assays such as enzyme-linked immunosorbent assay, fluorescent immunoassay, and chemiluminescent and electrochemiluminescent immunoassay. Despite great success, these strategies suffered from drawbacks such as limited spectral window capacity for multiplex detection and inability to provide absolute quantification of biomolecules. After recalling the sequences of tagging strategies, an apparent question is why not use stable isotopes from the start? A reasonable explanation is the lack of reliable means for accurate and precise quantification of stable isotopes at that time. The situation has changed greatly at present, since several atomic mass spectrometric measures for metal stable isotopes have been developed. Among the newly developed techniques, inductively coupled plasma mass spectrometry is an ideal technique to determine metal stable isotope-tagged biomolecules, for its high sensitivity, wide dynamic linear range, and more importantly multiplex and absolute quantification ability. Since the first published report by our group, metal stable isotope tagging has become a revolutionary technique and gained great success in biomolecule quantification. An exciting research highlight in this area is the development and application of the mass cytometer, which fully exploited the multiplexing potential of metal stable isotope tagging. It realized the simultaneous detection of dozens of parameters in single cells, accurate immunophenotyping in cell populations, through modeling of intracellular signaling network and undoubted discrimination of function and connection of cell subsets. Metal stable isotope tagging has great potential applications in hematopoiesis, immunology, stem cells, cancer, and drug screening related research and opened a post-fluorescence era of cytometry. Herein, we review the development of biomolecule quantification using metal stable isotope tagging. Particularly, the power of multiplex and absolute quantification is demonstrated. We address the advantages, applicable situations, and limitations of metal stable isotope tagging strategies and propose suggestions for future developments. The transfer of enzymatic or fluorescent tagging to metal stable isotope tagging may occur in many aspects of biological and clinical practices in the near future, just as the revolution from radioactive isotope tagging to fluorescent tagging happened in the past.

Why Methane Increasing in the Atmosphere is Pushing us Towards New Analytical Approaches for Stable Isotope Ratios

NASA Astrophysics Data System (ADS)

White, J. W. C.; Michel, S. E.; Vaughn, B. H.; Miller, J. B.; Masarie, K. A.; Dlugokencky, E. J.; Sherwood, O.; Tans, P. P.

2015-12-01

Methane is increasing again in the atmosphere after nearly a decade of stable concentrations. As methane has risen by 2.5 times since the beginning of the industrial era, such a rise in concentrations is not surprising. Carbon isotopes, however, make it clear that the recent rise is not simply a resumption of the dramatic rise in the 1900s, but that other causes are at play, and that multiple fluxes may be interacting to yield the observed rise. At the same time, cautious attention is focused on the Arctic, where vast stores of carbon are poised for release as frozen soils melt, and some of that carbon will be released as methane. These realities make it imperative that we improve our monitoring of methane and methane isotopes in the atmosphere. This talk will address the issues that we face in meeting this challenge in the NOAA Global Greenhouse Gas Reference Network, including targets for precision and accuracy needed to calculate regional and global fluxes, technological advances in analytical equipment, maintaining standards, ensuring adequate monitoring sites and meeting all of these needs in an era of funding cuts and uncertainty for environmental monitoring.

Lifetime Stable isotopes profiles in whale earplug: assessment of foraging and migrations in the Northern Hemisphere

NASA Astrophysics Data System (ADS)

Mansouri, F.; Crain, D.; Winfield, Z.; Trumble, S.; Usenko, S.

2017-12-01

Whale earplugs, historically used for aging, were used to reconstruct lifetime stable isotope profiles for carbon (δ13C) and nitrogen (δ15N) for individual whales by delaminating lamina within the earplug. These stable isotope profile, which provide Continuous lifetime records of feeding, foraging ecology, and migration, were determined for 20 individuals from 4 baleen species including fin, minke, humpback, and blue whales spanning more than a century (1869 - 2014) using stable isotope analysis. Approximately 1 mg tissue from each lamina (n=1200) was analyzed for carbon and nitrogen stable isotope using continuous flow isotope ratio mass spectrometer (CF-IRMS). This research using whale earplugs have combined age estimates with stable isotope measurements to reconstruct lifetime foraging profiles with a 6-month resolution, providing an unprecedented opportunity to assess periods and trends in dietary fluctuations as well as migration between different foraging area which have distinct isotope values. Trends with these profiles suggest long-term changing in migration, while annual variability highlights seasonal fasting and feeding. Isotopic ratios were also used to identify subpopulations of Atlantic fin whales, which enabled us to assign unidentified humpback and minke whales to the Atlantic or Pacific Oceans. This historical archive of data provides us an unprecedented tool to assess long term marine ecosystem and subsequently marine organism transition to alternate foraging area and shed light on the whale's population status in the Northern hemisphere.

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

NASA Astrophysics Data System (ADS)

Nowak-Lovato, K.

2014-12-01

Seepage from enhanced oil recovery, carbon storage, and natural gas sites can emit trace gases such as carbon dioxide, methane, and hydrogen sulfide. Trace gas emission at these locations demonstrate unique light stable isotope signatures that provide information to enable source identification of the material. Light stable isotope detection through surface monitoring, offers the ability to distinguish between trace gases emitted from sources such as, biological (fertilizers and wastes), mineral (coal or seams), or liquid organic systems (oil and gas reservoirs). To make light stable isotope measurements, we employ the ultra-sensitive technique, frequency modulation spectroscopy (FMS). FMS is an absorption technique with sensitivity enhancements approximately 100-1000x more than standard absorption spectroscopy with the advantage of providing stable isotope signature information. We have developed an integrated in situ (point source) system that measures carbon dioxide, methane and hydrogen sulfide with isotopic resolution and enhanced sensitivity. The in situ instrument involves the continuous collection of air and records the stable isotope ratio for the gas being detected. We have included in-line flask collection points to obtain gas samples for validation of isotopic concentrations using our in-house isotope ratio mass spectroscopy (IRMS). We present calibration curves for each species addressed above to demonstrate the sensitivity and accuracy of the system. We also show field deployment data demonstrating the capabilities of the system in making live dynamic measurements from an active source.

Arctic Ocean Cyclostratigraphy: An Alternative to Marine Oxygen Isotope curves as measures of Cryospheric and Sea-Level History

NASA Astrophysics Data System (ADS)

Cronin, T. M.; Marzen, R.; O'Regan, M.; Dwyer, G. S.

2016-12-01

The stable isotope compositions of biogenic carbonates have been used for paleoceanographic and paleoclimatic reconstructions for decades, and produced some of the most iconic records in the field. However, we still lack a fully mechanistic understanding of the stable isotope proxies, especially the biological overprint on the environmental signals termed "vital effects". A ubiquitous feature of stable isotope vital effects in marine calcifying organisms is a strong correlation between δ18O and δ13C in a range of values that are depleted from equilibrium. Two mechanisms have been proposed to explain this correlation, one based on kinetic isotope effects during CO2(aq)-HCO3- inter-conversion, the other based on equilibrium isotope exchange during pH dependent speciation of the dissolved inorganic carbon pool. Neither mechanism explains all the stable isotope features observed in biogenic carbonates. Here we present a fully kinetic model of biomineralization and its isotope effects using deep sea corals as a test organism. A key component of our model is the consideration of the enzyme carbonic anhydrase in catalyzing the CO2(aq)-HCO3- inter-conversion reactions in the extracellular calcifying fluid (ECF). We find that the amount of carbonic anhydrase not only modulates the carbonate chemistry of the calcifying fluid, but also helps explain the slope of the δ18O-δ13C correlation. With this model, we are not only able to fit deep sea coral data, but also explain the stable isotope vital effects of other calcifying organisms. This fully kinetic model of stable isotope vital effects and the underlying calcification dynamics may also help us better understand mechanisms of other paleoceanographic tracers in biogenic carbonates, including boron isotopes and trace metal proxies.

Considerations in the development of the utility of stable isotopes in science, medicine, and agriculture, and environmental studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matwiyoff, N.A.

1976-01-01

The prospects for the broad scale development of the utility of stable isotopes in science, medicine, agriculture, and environmental studies are considered with emphasis on the current status of isotope production, synthesis of isotopically labelled compounds, and analytical techniques.

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

EPA Science Inventory

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

Insights into Wilson's Warbler migration from analyses of hydrogen stable-isotope ratios

Treesearch

Jeffrey F. Kelly; Viorel Atudorei; Zachary D. Sharp; Deborah M. Finch

2002-01-01

Our ability to link the breeding locations of individual passerines to migration stopover sites and wintering locations is limited. Stable isotopes of hydrogen contained in bird feathers have recently shown potential in this regard. We measured hydrogen stable-isotope ratios (deltaD) of feathers from breeding, migrating, and wintering Wilson's Warblers. Analyses...

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...

Comparing compound-specific and bulk stable nitrogen isotope trophic discrimination factors across multiple freshwater fish species and diets

USDA-ARS?s Scientific Manuscript database

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

Isotope Tales: Remaining Problems, Unsolvable Questions, and Gentle Successes

NASA Astrophysics Data System (ADS)

fogel, marilyn; bradley, christina; newsome, seth; filipp, fabian

2014-05-01

Earth's biomes function and adapt today as climate changes and ecosystems and the organisms within them adapt. Stable isotope biogeochemistry has had a major influence in understanding climate perturbations and continues to be an active area of research on many fronts. Banking on the success of compound specific stable isotope analyses of amino acids, nitrogen, carbon, and hydrogen isotopes continue to reveal subtle shifts in oceanic food webs and metabolic changes in microbes, plants, and animals. A biochemical understanding of exactly how organisms process and partition stable isotopes during metabolism remains unsolved, but is required if this field is to move beyond description to quantitation. Although the patterns of carbon and nitrogen isotopes are fairly well established in the common amino acids, we need to consider specifics: How do shifting metabolic pathways (metabolomics) influence the outcome of stable isotope partitioning? What influence does the gut microflora in animals have on isotopic labeling? What are the intramolecular isotope patterns of common amino acids and what do they tell us? What can be learned with other isotope systems, such as hydrogen? Results and ideas of how to move forward in this field will be presented starting at the molecular level and ending with ecosystems.

[A review of water and carbon flux partitioning and coupling in SPAC using stable isotope techniques].

PubMed

Xu, Xiao Wu; Yu, Xin Xiao; Jia, Guo Dong; Li, Han Zhi; Lu, Wei Wei; Liu, Zi Qiang

2017-07-18

Soil-vegetation-atmosphere continuum (SPAC) is one of the important research objects in the field of terrestrial hydrology, ecology and global change. The process of water and carbon cycling, and their coupling mechanism are frontier issues. With characteristics of tracing, integration and indication, stable isotope techniques contribute to the estimation of the relationship between carbon sequestration and water consumption in ecosystems. In this review, based on a brief introduction of stable isotope principles and techniques, the applications of stable isotope techniques to water and carbon exchange in SPAC using optical stable isotope techniques were mainly explained, including: partitioning of net carbon exchange into photosynthesis and respiration; partitioning of evapotranspiration into transpiration and evaporation; coupling of water and carbon cycle at the ecosystem scale. Advanced techniques and methods provided long-term and high frequency measurements for isotope signals at the ecosystem scale, but the issues about the precision and accuracy for measurements, partitioning of ecosystem respiration, adaptability for models under non-steady state, scaling up, coupling mechanism of water and carbon cycles, were challenging. The main existing research findings, limitations and future research prospects were discussed, which might help new research and technology development in the field of stable isotope ecology.

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 can be written as+15 μUr.

Food web heterogeneity and succession in created saltmarshes

USGS Publications Warehouse

Nordstrom, M C; Demopoulos, Amanda W.J.; Whitcraft, CR; Rismondo, A.; McMillan, P.; Gonzales, J P; Levin, L A

2015-01-01

1. Ecological restoration must achieve functional as well as structural recovery. Functional metrics for reestablishment of trophic interactions can be used to complement traditional monitoring of structural attributes. In addition, topographic effects on food web structure provide added information within a restoration context; often, created sites may require spatial heterogeneity to effectively match structure and function of natural habitats. 2. We addressed both of these issues in our study of successional development of benthic food web structure, with focus on bottom–up driven changes in macroinvertebrate consumer assemblages in the salt marshes of the Venice Lagoon, Italy. We combined quantified estimates of the changing community composition with stable isotope data (13C:12C and 15N:14N) to compare the general trophic structure between created (2–14 years) marshes and reference sites and along topographic elevation gradients within salt marshes. 3. Macrofaunal invertebrate consumers exhibited local, habitat-specific trophic patterns. Stable isotope-based trophic structure changed with increasing marsh age, in particular with regards to mid-elevation (Salicornia) habitats. In young marshes, the mid-elevation consumer signatures resembled those of unvegetated ponds. The mid elevation of older and natural marshes had a more distinct Salicornia-zone food web, occasionally resembling that of the highest (Sarcocornia-dominated) elevation. In summary, this indicates that primary producers and availability of vascular plant detritus structure consumer trophic interactions and the flow of carbon. 4. Functionally different consumers, subsurface-feeding detritivores (Oligochaeta) and surface grazers (Hydrobia sp.), showed distinct but converging trajectories of isotopic change over time, indicating that successional development may be asymmetric between ‘brown’ (detrital) guilds and ‘green’ (grazing) guilds in the food web. 5. Synthesis and applications. Created marsh food webs converged into a natural state over about a decade, with successional shifts seen in both consumer community composition and stable isotope space. Strong spatial effects were noted, highlighting the utility of stable isotopes to evaluate functional equivalence in spatially heterogeneous systems. Understanding the recovery of functional properties such as food web support, and their inherent spatial variability, is key to planning and managing successful habitat restoration.

Stable isotope geochemistry of pore waters from the New Jersey shelf - No evidence for Pleistocene melt water

NASA Astrophysics Data System (ADS)

van Geldern, Robert; Hayashi, Takeshi; Böttcher, Michael E.; Mottl, Michael J.; Barth, Johannes A. C.; Stadler, Susanne

2013-04-01

Scientific drillings in the 1970s revealed the presence of a large fresh water lens below the New Jersey Shelf. The origin and age of this fresh water body is still under debate. Groundwater flow models suggest that the water mainly originates from glacial melt water that entered the ground below large continental ice sheets during the last glacial maximum (LGM), whereas other studies suggest an age up to late Miocene. In this study, interstitial water was sampled during the Integrated Ocean Drilling Program (IODP) expedition 313 "New Jersey Shallow Shelf" (Mountain et al., 2010) and analyzed for water chemistry and stable isotope ratios (van Geldern et al, 2013). The pore fluid stable isotope values define a mixing line with end members that have oxygen and hydrogen isotope values of -7.0‰ and -41‰ for fresh water, and -0.8‰ and -6‰ for saltwater, respectively. The analyses revealed the following sources of fluids beneath the shelf: (1) modern rainwater, (2) modern seawater, and (3) a brine that ascends from deep sediments. The stable isotope composition of the water samples indicates modern meteoric recharge from New Jersey onshore aquifers as the fresh-water end member. This contradicts earlier views on the formation of the New Jersey fresh water lens, as it does not support the ice-age-origin theory. The salt-water end member is identical to modern New Jersey shelf seawater. Lower core parts of the drilling sites are characterized by mixing with a brine that originates from evaporites in the deep underground and that ascends via faults into the overlying sediments. The geochemical data from this study may provide the basis for an approach to construct a transect across the New Jersey shallow shelf since they fill a missing link in the shelf's geochemical profile. They also lay foundations for future research on hardly explored near-shore freshwater resources. References Mountain, G. and the Expedition 313 Scientists, 2010, Proceedings of the Integrated Ocean Drilling Program, Volume 313, Tokyo, available at: http://publications.iodp.org/proceedings/313/313toc.htm. van Geldern, R., Hayashi, T., Böttcher, M. E., Mottl, M. J., Barth, J. A. C., and Stadler, S., 2013, Stable isotope geochemistry of pore waters and marine sediments from the New Jersey shelf: Methane formation and fluid origin: Geosphere, v. 9, no. 1, p. in press.

Preparation, certification and validation of a stable solid spike of uranium and plutonium coated with a cellulose derivative for the measurement of uranium and plutonium content in dissolved nuclear fuel by isotope dilution mass spectrometry.

PubMed

Surugaya, Naoki; Hiyama, Toshiaki; Verbruggen, André; Wellum, Roger

2008-02-01

A stable solid spike for the measurement of uranium and plutonium content in nitric acid solutions of spent nuclear fuel by isotope dilution mass spectrometry has been prepared at the European Commission Institute for Reference Materials and Measurements in Belgium. The spike contains about 50 mg of uranium with a 19.838% (235)U enrichment and 2 mg of plutonium with a 97.766% (239)Pu abundance in each individual ampoule. The dried materials were covered with a thin film of cellulose acetate butyrate as a protective organic stabilizer to resist shocks encountered during transportation and to eliminate flaking-off during long-term storage. It was found that the cellulose acetate butyrate has good characteristics, maintaining a thin film for a long time, but readily dissolving on heating with nitric acid solution. The solid spike containing cellulose acetate butyrate was certified as a reference material with certified quantities: (235)U and (239)Pu amounts and uranium and plutonium amount ratios, and was validated by analyzing spent fuel dissolver solutions of the Tokai reprocessing plant in Japan. This paper describes the preparation, certification and validation of the solid spike coated with a cellulose derivative.

Using stable isotope systematics and trace metals to constrain the dispersion of fish farm pollution

NASA Astrophysics Data System (ADS)

Torchinsky, A.; Shiel, A. E.; Price, M.; Weis, D. A.

2010-12-01

Fish farming is a growing industry of great economic importance to coastal communities. Unfortunately, open-net fish farming is associated with the release of organic and metal pollution, which has the potential to adversely affect the coastal marine environment. The dispersion of fish farm pollution and its environmental impact are not well understood/quantified. Pollutants released by fish farms include organic products such as uneaten feed pellets and fish feces, as well as chemicals and pharmaceuticals, all of which may enter marine ecosystems. In this study, we took advantage of bioaccumulation in passive suspension feeding Manila Clams collected at varying distances from an open-net salmon farm located in the Discovery Islands of British Columbia. Measurements of stable C and N isotopes, as well as trace metal concentrations, in the clams were used to investigate the spread of pollutants by detecting the presence of fish farm waste in the clams’ diet. Lead isotopic measurements were used to identify other significant anthropogenic pollution sources, which may impact the study area. Clams located within the areal extent of waste discharged by a fish farm are expected to exhibit anomalous light stable isotope ratios and metal concentrations, reflecting the presence of pollutants accumulated directly from seawater and from their diet. Clams were collected in the Discovery Islands from three sites in the Octopus Islands, located 850 m, 2100 m and 3000 m north of the Cyrus Rocks salmon farm (near Quadra Island) and from a reference site on Penn Island. Light stable isotope ratios (δN = ~10‰, with little variation between sites, and δC from -14.5 to -17.3‰) of the clams suggest that the most distal site (i.e., 3000 m away) is most impacted by organic fish farm waste (i.e., food pellets and feces) and that contributions of organic waste actually decrease closer to the farm. Not surprisingly, the smallest contribution of organic waste was detected in clams from the reference site. It is thought that resuspension of particulate waste could be responsible for concentrating waste far from the fish farm. No pattern was observed in the trace metal concentration measurements (Cu = 4.11 - 9.64 ppm, Zn 40.0 - 107 ppm and Pb 0.008 - 0.086 ppm) of the clams suggesting differences in the dispersion of metal contaminants and organic waste. Lead isotope ratios (1.14874 to 1.74100 for 206Pb /207Pb and 2.07579 to 2.10615 for 208Pb /206Pb) indicate the importance of anthropogenic Pb sources in the study area (i.e., unleaded gasoline and diesel fuel consumption and metal smelting), however, the anthropogenic Pb sources are unlikely to be associated with the open-net salmon farm. Waste dispersion from open-net fish farms is complicated by physical oceanographic conditions, which characterize individual study areas, this must be taken into account when interpreting results and designing future studies.

Fractionation of metal stable isotopes by higher plants

USGS Publications Warehouse

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

2009-01-01

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

[Research progress on food sources and food web structure of wetlands based on stable isotopes].

PubMed

Chen, Zhan Yan; Wu, Hai Tao; Wang, Yun Biao; Lyu, Xian Guo

2017-07-18

The trophic dynamics of wetland organisms is the basis of assessing wetland structure and function. Stable isotopes of carbon and nitrogen have been widely applied to identify trophic relationships in food source, food composition and food web transport in wetland ecosystem studies. This paper provided an overall review about the current methodology of isotope mixing model and trophic level in wetland ecosystems, and discussed the standards of trophic fractionation and baseline. Moreover, we characterized the typical food sources and isotopic compositions of wetland ecosystems, summarized the food sources in different trophic levels of herbivores, omnivores and carnivores based on stable isotopic analyses. We also discussed the limitations of stable isotopes in tra-cing food sources and in constructing food webs. Based on the current results, development trends and upcoming requirements, future studies should focus on sample treatment, conservation and trophic enrichment measurement in the wetland food web, as well as on combing a variety of methodologies including traditional stomach stuffing, molecular markers, and multiple isotopes.

Patterns in Stable Isotope Values of Nitrogen and Carbon in Particulate Matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras

EPA Science Inventory

Stable isotope measurements of nitrogen and carbon (15N, 13ddC) are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is crit...

Stable isotope ratios and reforestation potential in Acacia koa populations on Hawai'i

Treesearch

Shaneka Lawson; Carrie Pike

2017-01-01

Stable carbon and nitrogen isotopes can be influenced by a multitude of factors including elevation, precipitation rate, season, and temperature. This work examined variability in foliar stable carbon (δ13C) and nitrogen (δ15N) isotope ratios of koa (Acacia koa) across 17 sites on Hawai'i Island, delineated by elevation and precipitation...

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.

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

PubMed

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

2016-01-01

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

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

PubMed Central

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

2016-01-01

Hydrogen stable isotopes (δ2H) have recently been used to complement δ13C and δ15N in food web studies due to their potentially greater power to separate sources of organic matter in aquatic food webs. However, uncertainties remain regarding the use of δ2H, since little is known about the potential variation in the amount of exchangeable hydrogen (Hex) among common sample materials or the patterns of δ2H when entire food webs are considered. We assessed differences in Hex among the typical sample materials in freshwater studies and used δ2H, δ13C and δ15N to compare their effectiveness in tracing allochthonous matter in food webs of two small temperate lakes. Our results showed higher average amounts of Hex in animal tissues (27% in fish and macroinvertebrates, 19% in zooplankton) compared to most plant material (15% in terrestrial plants and 8% in seston/periphyton), with the exception of aquatic vascular plants (23%, referred to as macrophytes). The amount of Hex correlated strongly with sample lipid content (inferred from C:N ratios) in fish and zooplankton samples. Overall, the three isotopes provided good separation of sources (seston, periphyton, macrophytes and allochthonous organic matter), particularly the δ2H followed by δ13C. Aquatic macrophytes revealed unexpectedly high δ2H values, having more elevated δ2H values than terrestrial organic matter with direct implications for estimating consumer allochthony. Organic matter from macrophytes significantly contributed to the food webs in both lakes highlighting the need to include macrophytes as a potential source when using stable isotopes to estimate trophic structures and contributions from allochthonous sources. PMID:27167517

Stable isotope-labelled feed nutrients to assess nutrient-specific feed passage kinetics in ruminants.

PubMed

Warner, Daniel; Dijkstra, Jan; Hendriks, Wouter H; Pellikaan, Wilbert F

2014-03-30

Knowledge of digesta passage kinetics in ruminants is essential to predict nutrient supply to the animal in relation to optimal animal performance, environmental pollution and animal health. Fractional passage rates (FPR) of feed are widely used in modern feed evaluation systems and mechanistic rumen models, but data on nutrient-specific FPR are scarce. Such models generally rely on conventional external marker techniques, which do not always describe digesta passage kinetics in a satisfactory manner. Here the use of stable isotope-labelled dietary nutrients as a promising novel tool to assess nutrient-specific passage kinetics is discussed. Some major limitations of this technique include a potential marker migration, a poor isotope distribution in the labelled feed and a differential disappearance rate of isotopes upon microbial fermentation in non-steady state conditions. Such limitations can often be circumvented by using intrinsically stable isotope-labelled plant material. Data are limited but indicate that external particulate markers overestimate rumen FPR of plant fibre compared with the internal stable isotope markers. Stable isotopes undergo the same digestive mechanism as the labelled feed components and are thus of particular interest to specifically measure passage kinetics of digestible dietary nutrients. © 2013 Society of Chemical Industry.

Discrimination factors of carbon and nitrogen stable isotopes in meerkat feces

PubMed Central

2017-01-01

Stable isotope analysis of feces can provide a non-invasive method for tracking the dietary habits of nearly any mammalian species. While fecal samples are often collected for macroscopic and genetic study, stable isotope analysis can also be applied to expand the knowledge of species-specific dietary ecology. It is somewhat unclear how digestion changes the isotope ratios of animals’ diets, so more controlled diet studies are needed. To date, most diet-to-feces controlled stable isotope experiments have been performed on herbivores, so in this study I analyzed the carbon and nitrogen stable isotope ratios in the diet and feces of the meerkat (Suricata suricatta), a small omnivorous mammal. The carbon trophic discrimination factor between diet and feces (Δ13Cfeces) is calculated to be 0.1 ± 1.5‰, which is not significantly different from zero, and in turn, not different than the dietary input. On the other hand, the nitrogen trophic discrimination factor (Δ15Nfeces) is 1.5 ± 1.1‰, which is significantly different from zero, meaning it is different than the average dietary input. Based on data generated in this experiment and a review of the published literature, carbon isotopes of feces characterize diet, while nitrogen isotope ratios of feces are consistently higher than dietary inputs, meaning a discrimination factor needs to be taken into account. The carbon and nitrogen stable isotope values of feces are an excellent snapshot of diet that can be used in concert with other analytical methods to better understand ecology, diets, and habitat use of mammals. PMID:28626611

Tracing metal-silicate segregation and late veneer in the Earth and the ureilite parent body with palladium stable isotopes

NASA Astrophysics Data System (ADS)

Creech, J. B.; Moynier, F.; Bizzarro, M.

2017-11-01

Stable isotope studies of highly siderophile elements (HSE) have the potential to yield valuable insights into a range of geological processes. In particular, the strong partitioning of these elements into metal over silicates may lead to stable isotope fractionation during metal-silicate segregation, making them sensitive tracers of planetary differentiation processes. We present the first techniques for the precise determination of palladium stable isotopes by MC-ICPMS using a 106Pd-110Pd double-spike to correct for instrumental mass fractionation. Results are expressed as the per mil (‰) difference in the 106Pd/105Pd ratio (δ106Pd) relative to an in-house solution standard (Pd_IPGP) in the absence of a certified Pd isotopic standard. Repeated analyses of the Pd isotopic composition of the chondrite Allende demonstrate the external reproducibility of the technique of ±0.032‰ on δ106Pd. Using these techniques, we have analysed Pd stable isotopes from a range of terrestrial and extraterrestrial samples. We find that chondrites define a mean δ106Pdchondrite = -0.19 ± 0.05‰. Ureilites reveal a weak trend towards heavier δ106Pd with decreasing Pd content, similar to recent findings based on Pt stable isotopes (Creech et al., 2017), although fractionation of Pd isotopes is significantly less than for Pt, possibly related to its weaker metal-silicate partitioning behaviour and the limited field shift effect. Terrestrial mantle samples have a mean δ106Pdmantle = -0.182 ± 0.130‰, which is consistent with a late-veneer of chondritic material after core formation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

Estimates of groundwater recharge rates and sources in the East Mountain area, Eastern Bernalillo County, New Mexico, 2005-12

USGS Publications Warehouse

Rice, Steven E.; Crilley, Dianna M.

2014-01-01

Stable isotope data from springs and snowpacks sampled in the East Mountain area were compared with local, regional, and global meteoric water lines and were analyzed along with values representing the stable isotope composition of winter precipitation and summer monsoonal rains. Results of the stable isotope analysis from springs in this study suggested that winter precipitation is the primary source of groundwater recharge to the aquifers supplying the springs, but there is a component of more isotopically enriched precipitation being recharged as well, likely from summer monsoonal rains. Specific conductance, groundwater-level hydrographs, snowpack chemistry, and snow-water equivalent data were used to inform the analyses and corroborate the findings of the CMB and stable isotope results.

Ion exchange separation of chromium from natural water matrix for stable isotope mass spectrometric analysis

USGS Publications Warehouse

Ball, J.W.; Bassett, R.L.

2000-01-01

A method has been developed for separating the Cr dissolved in natural water from matrix elements and determination of its stable isotope ratios using solid-source thermal-ionization mass spectrometry (TIMS). The separation method takes advantage of the existence of the oxidized form of Cr as an oxyanion to separate it from interfering cations using anion-exchange chromatography, and of the reduced form of Cr as a positively charged ion to separate it from interfering anions such as sulfate. Subsequent processing of the separated sample eliminates residual organic material for application to a solid source filament. Ratios for 53Cr/52Cr for National Institute of Standards and Technology Standard Reference Material 979 can be measured using the silica gel-boric acid technique with a filament-to-filament standard deviation in the mean 53Cr/52Cr ratio for 50 replicates of 0.00005 or less. (C) 2000 Elsevier Science B.V. All rights reserved.

Stable isotopes suggest differences in diet between historic and reintroduced Przewalskís horses in the Gobi desert

NASA Astrophysics Data System (ADS)

Burnik Šturm, Martina; Spasskaya, Natalia N.; Sablin, Mikhail V.; Voigt, Christian C.; Kaczensky, Petra

2016-04-01

In historic times, two wild equid species, the Przewalski᾽s horse (PH; Equus ferus przewalskii) and the Asiatic wild ass (khulan, KH; Equus hemionus), roamed the Eurasian steppes. By the end of the 1960s, PHs had been driven to extinction in the wild and the range of KHs became severely restricted to the least productive habitats. However, PHs survived in captivity and reintroductions since the 1990s have brought the species back to parts of its native range in Mongolia and northern China where they again overlap with KHs. Ecological research on PHs and KHs has increased in recent years, but very little information is available on the ecology of the original PHs prior to extinction in the wild. We applied stable isotope analysis (13C, 15N, and 2H) of segmentally cut tail hair of PHs and KHs, collected during expeditions in NW China and SW Mongolia in 1889-1899, to draw inferences about the species feeding ecology. We compared tail hair isotope patterns of historic individuals to those of their extant counterparts from the Mongolian Gobi. A previous study of isotopic tail hair signatures of extant PHs (N=6) and KHs (N=6) suggested species specific differences in diet, with PHs being year-round grazers, but KHs switching between being grazers in summer and mixed feeders in winter (Burnik Šturm et al., in prep.). The comparison of isotope patterns of extant with historic samples confirms diet seasonality in historic KHs (N=3), but detects the same seasonality in five out of six PHs, suggesting that historic PHs had a different isotopic dietary niche than extant PHs. While we are still unable to fully understand the underlying reasons for this change in PHs, our results clearly suggest that the isotopic dietary niche of PHs was wider in the past, suggesting a higher diet flexibility, and overlapped with that of KHs, suggesting a high competition potential over Gobi pastures between the two equid species in historic times. Reference: Burnik Šturm, M., Ganbaatar, O., Voigt, C.C., Kaczensky, P. Stable isotopes reveal differences in the feeding ecology of three sympatric equid species in Dzungarian Gobi, Mongolia (in prep.)

Human variation: delta/sup 13/C in adult bone collagen and the relation to diet in an isochronous C/sub 4/ (maize) archaeological population

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bumsted, M.P.

1984-10-01

Analysis of the stable isotopes of carbon (/sup 13/C and /sup 12/C in the standard ratio delta/sup 13/C) can distinguish the relative contributions of meat, cereals, and other plant foods to the diets of prehistoric people. This dissertation has examined an isochronous (non-cemetery) population of prehistoric Americans to ascertain the natural variation in isotopic composition amongst a group of maize-eaters. The seventeen adult females and fifteen adult males represent the largest human data set of prehistoric or contemporary samples for study of natural isotopic enrichment in which genetic, economic, disease, and temporal variables were controlled. Procedures for purifying remnant bonemore » protein from archaeological samples were developed or modified specifically to determine isotopic measurement. Cryogenic milling, cold acid demineralizing, gelatinizing, and an XAD-2 resin column were used to remove soil contaminants while preserving the chemical integrity of the bone protein. Measurements of total elemental carbon, hydrogen, and nitrogen of the unprocessed bone; amino acid analysis of selected gelatin samples; and stable carbon isotopic analysis were used to assess sample quality. Isotope values were lognormally distributed in this population (anti X = -1.15%) with the distribution and the means amongst males (anti X = -1.18%) significantly different from that of females (anti X = -1.13%). The isotopic diet model can be graphed with equilateral triangular coordinates to represent the relative contributions of meat, maize, and other plant foods. The graph can predict the maximum food contributions to the delta/sup 13/C of the prehistoric individuals measured. Isotopic variation in human bone protein is only partly due to the variable amount of enriched foods in the diet. Tissue enrichment which occurs at various metabolic levels must also be considered. 316 references, 20 figures, 10 tables.« less

[Stable Isotopes Characters of Soil Water Movement in Shijiazhuang City].

PubMed

Chen, Tong-tong; Chen, Hui; Han, Lu; Xing, Xing; Fu, Yang-yang

2015-10-01

In this study, we analyzed the stable hydrogen and oxygen isotope values of precipitation, soil water, irrigation water that collected in Shijiazhuang City from April 2013 to May 2014 to investigate the changing rule of the stable isotopes in different soil profiles and the process of soil water movement according to using the isotope tracer technique. The results showed that the mean excess deuterium of the local precipitation was -6.188 5 per thousand. Those reflected that the precipitation in Shijiazhuang City mainly brought by the monsoon from the ocean surface moisture, and also to some extent by the local evaporation. Precipitation was the main source of the soil water and the irrigation water played the supplementary role. In the rainy season, precipitation was enough to supply the soil water. The stable oxygen isotopes at 10-100 cm depth decreased with the increase of depth, the maximum depth of evaporation in the rainy season reached 40 cm. The peak of stable oxygen isotopes of soil water pushed down along the profile, which was infected by the interaction of the precipitation infiltration, evaporation and the mixing water.

STABLE ISOTOPIC EVIDENCE OF CARBON AND NITROGEN USE IN CULTURED ECTOMYCORRHIZAL AND SAPROTROPHIC FUNGI

EPA Science Inventory

Stable isotopes in sporocarps have proven useful for inferring ectomycorrhizal or saprotrophic status and understanding carbon (C) and nitrogen (N) utilization. However, greater understanding of processes producing isotopic concentrations is needed. We measured natural abundanc...

STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS

EPA Science Inventory

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

Why we need a centralized repository for isotopic data

USDA-ARS?s Scientific Manuscript database

Stable isotopes encode the origin and integrate the history of matter; thus, their analysis offers tremendous potential to address questions across diverse scientific disciplines. Indeed, the broad applicability of stable isotopes, coupled with advancements in high-throughput analysis, have created ...

A quantitative approach to combine sources in stable isotope mixing models

EPA Science Inventory

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

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

EPA Science Inventory

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

A Teaching Exercise to Introduce Stable Isotope Fractionation of Metals into Geochemistry Courses

ERIC Educational Resources Information Center

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

2013-01-01

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

Seasonal Cyclicity in Trace Elements and Stable Isotopes of Modern Horse Enamel.

PubMed

de Winter, Niels J; Snoeck, Christophe; Claeys, Philippe

2016-01-01

The study of stable isotopes in fossil bioapatite has yielded useful results and has shown that bioapatites are able to faithfully record paleo-environmental and paleo-climatic parameters from archeological to geological timescales. In an effort to establish new proxies for the study of bioapatites, intra-tooth records of enamel carbonate stable isotope ratios from a modern horse are compared with trace element profiles measured using laboratory micro X-Ray Fluorescence scanning. Using known patterns of tooth eruption and the relationship between stable oxygen isotopes and local temperature seasonality, an age model is constructed that links records from six cheek upper right teeth from the second premolar to the third molar. When plotted on this age model, the trace element ratios from horse tooth enamel show a seasonal pattern with a small shift in phase compared to stable oxygen isotope ratios. While stable oxygen and carbon isotopes in tooth enamel are forced respectively by the state of the hydrological cycle and the animal's diet, we argue that the seasonal signal in trace elements reflects seasonal changes in dust intake and diet of the animal. The latter explanation is in agreement with seasonal changes observed in carbon isotopes of the same teeth. This external forcing of trace element composition in mammal tooth enamel implies that trace element ratios may be used as proxies for seasonal changes in paleo-environment and paleo-diet.

Seasonal Cyclicity in Trace Elements and Stable Isotopes of Modern Horse Enamel

PubMed Central

Snoeck, Christophe; Claeys, Philippe

2016-01-01

The study of stable isotopes in fossil bioapatite has yielded useful results and has shown that bioapatites are able to faithfully record paleo-environmental and paleo-climatic parameters from archeological to geological timescales. In an effort to establish new proxies for the study of bioapatites, intra-tooth records of enamel carbonate stable isotope ratios from a modern horse are compared with trace element profiles measured using laboratory micro X-Ray Fluorescence scanning. Using known patterns of tooth eruption and the relationship between stable oxygen isotopes and local temperature seasonality, an age model is constructed that links records from six cheek upper right teeth from the second premolar to the third molar. When plotted on this age model, the trace element ratios from horse tooth enamel show a seasonal pattern with a small shift in phase compared to stable oxygen isotope ratios. While stable oxygen and carbon isotopes in tooth enamel are forced respectively by the state of the hydrological cycle and the animal’s diet, we argue that the seasonal signal in trace elements reflects seasonal changes in dust intake and diet of the animal. The latter explanation is in agreement with seasonal changes observed in carbon isotopes of the same teeth. This external forcing of trace element composition in mammal tooth enamel implies that trace element ratios may be used as proxies for seasonal changes in paleo-environment and paleo-diet. PMID:27875538

Stable carbon isotopes as an indicator for soil degradation in an alpine environment (Urseren Valley, Switzerland).

PubMed

Schaub, Monika; Alewell, Christine

2009-05-01

Analyses of soil organic carbon (SOC) content and stable carbon isotope signatures (delta(13)C) of soils were assessed for their suitability to detect early stage soil erosion. We investigated the soils in the alpine Urseren Valley (southern central Switzerland) which are highly impacted by soil erosion. Hill slope transects from uplands (cambisols) to adjacent wetlands (histosols and histic to mollic gleysols) differing in their intensity of visible soil erosion, and reference wetlands without erosion influence were sampled. Carbon isotopic signature and SOC content of soil depth profiles were determined. A close correlation of delta(13)C and carbon content (r > 0.80) is found for upland soils not affected by soil erosion, indicating that depth profiles of delta(13)C of these upland soils mainly reflect decomposition of SOC. Long-term disturbance of an upland soil is indicated by decreasing correlation of delta(13)C and SOC (r

Inductively coupled plasma mass spectrometry for stable isotope metabolic tracer studies of living systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luong, Elise

1999-05-10

This dissertation focuses on the development of methods for stable isotope metabolic tracer studies in living systems using inductively coupled plasma single and dual quadrupole mass spectrometers. Sub-nanogram per gram levels of molybdenum (Mo) from human blood plasma are isolated by the use of anion exchange alumina microcolumns. Million-fold more concentrated spectral and matrix interferences such as sodium, chloride, sulfate, phosphate, etc. in the blood constituents are removed from the analyte. The recovery of Mo from the alumina column is 82 ± 5% (n = 5). Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) is utilized for the quantitative ultra-tracemore » concentration determination of Mo in bovine and human blood samples. The average Mo concentration in reference bovine serum determined by this method is 10.2 ± 0.4 ng/g, while the certified value is 11.5 ± 1.1 ng/g (95% confidence interval). The Mo concentration of one pool of human blood plasma from two healthy male donors is 0.5 ± 0.1 ng/g. The inductively coupled plasma twin quadrupole mass spectrometer (ICP-TQMS) is used to measure the carbon isotope ratio from non-volatile organic compounds and bio-organic molecules to assess the ability as an alternative analytical method to gas chromatography combustion isotope ratio mass spectrometry (GC-combustion-IRMS). Trytophan, myoglobin, and β-cyclodextrin are chosen for the study, initial observation of spectral interference of 13C + with 12C 1H + comes from the incomplete dissociation of myoglobin and/or β-cyclodextrin.« less

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

NASA Astrophysics Data System (ADS)

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

2012-12-01

Stable carbon isotope ratios (δ13C) are a powerful tool for inferring carbon sources and mixing ratios of injected and baseline CO2 in storage reservoirs. Furthermore, CO2 releasing and consuming processes can be deduced if the isotopic compositions of end-members are known. At low CO2 pressures (pCO2), oxygen isotope ratios (δ18O) of CO2 usually assume the δ18O of the water plus a temperature-dependent isotope fractionation factor. However, at very high CO2 pressures as they occur in CO2 storage reservoirs, the δ18O of the injected CO2 may in fact change the δ18O of the reservoir brine. Hence, changing δ18O of brine constitutes an additional tracer for reservoir-internal carbon dynamics and allows the determination of the amount of free phase CO2 present in the reservoir (Johnson et al. 2011). Further systematic research to quantify carbon and oxygen isotope fractionation between the involved inorganic carbon species (CO2, H2CO3, HCO3-, CO32-, carbonate minerals) and kinetic and equilibrium isotope effects during gas-water-rock interactions is necessary because p/T conditions and salinities in CO2 storage reservoirs may exceed the boundary conditions of typical environmental isotope applications, thereby limiting the accuracy of stable isotope monitoring approaches in deep saline formations (Becker et al. 2011). In doing so, it is crucial to compare isotopic patterns observed in laboratory experiments with artificial brines to similar experiments with original fluids from representative field sites to account for reactions of dissolved inorganic carbon (DIC) with minor brine components. In the CO2ISO-LABEL project, funded by the German Ministry for Education and Research, multiple series of laboratory experiments are conducted to determine the influence of pressure, temperature and brine composition on the δ13C of DIC and the δ18O of brines in water-CO2-rock reactions with special focus placed on kinetics and stable oxygen and carbon isotope fractionation factors. Laboratory experiments with original reservoir fluids from CO2 storage reservoirs in Canada using supercritical fluid extraction reactors are being conducted at temperatures of up to 200 °C and CO2 pressures of up to 20 MPa. Preliminary results show that equilibration times for δ18O in high saline waters increase by an order of magnitude compared to fresh water, with exact times depending on CO2 partial pressure, stirring and the contact area between the phases. References Becker, V. et al., 2011. Predicting δ13CDIC dynamics in CCS: A scheme based on a review of inorganic carbon chemistry under elevated pressures and temperatures. International Journal of Greenhouse Gas Control, 5, pp.1250-1258. Johnson, G. et al., 2011. Using oxygen isotope ratios to quantitatively assess trapping mechanisms during CO2 injection into geological reservoirs: The Pembina case study. Chemical Geology, 283(3-4), pp.185-193.

Particular geoscientific perspectives on stable isotope analysis in the arboreal system

NASA Astrophysics Data System (ADS)

Helle, Gerhard; Balting, Daniel; Pauly, Maren; Slotta, Franziska

2017-04-01

In geosciences stable isotopes of carbon, oxygen and hydrogen from the tree ring archive have been used for several decades to trace the course of past environmental and climatological fluctuations. In contrast to ice cores, the tree ring archive is of biological nature (like many other terrestrial archives), but provides the opportunity to establish site networks with very high resolution in space and time. Many of the basic physical mechanisms of isotope shifts are known, but biologically mediated processes may lead to isotope effects that are poorly understood. This implies that the many processes within the arboreal system leading to archived isotope ratios in wood material are governed by a multitude of environmental variables that are not only tied to the isotopic composition of atmospheric source values (precipitation, CO2), but also to seasonally changing metabolic flux rates and pool sizes of photosynthates within the trees. Consequently, the extraction of climate and environmental information is particularly challenging and reconstructions are still of rather qualitative nature. Over the last 10 years or so, monitoring studies have been implemented to investigate stable isotope, climate and environmental signal transfer within the arboreal system to develop transfer or response functions that can translate the relevant isotope values extracted from tree rings into climate or other environmental variables. To what extent have these efforts lead to a better understanding that helps improving the meaningfulness of tree ring isotope signals? For example, do monitoring studies help deciphering the causes for age-related trends in tree ring stable isotope sequences that are published in a growing number of papers. Are existing monitoring studies going into detail enough or is it already too much effort for the outcome? Based on what we know already particularly in mesic habitats, tree ring stable isotopes are much better climate proxies than other tree ring parameters. However, millennial or multi-millennial high quality reconstructions from tree ring isotopes are still rare. This is because of i) methodological constraints related to mass spectrometric analyses and ii) the nature of tree-ring chronologies that are put together by many trees of various individual ages. In view of this: What is the state-of-the-art in high throughput tree ring stable isotope analyses? Is it necessary to advance existing methodologies further to conserve the annual time resolution provided by the tree-ring archive? Other terrestrial archives, like lake sediments and speleothems rarely provide annually resolved stable isotope data. Furthermore, certain tree species from tropical or sub-tropical regions cannot be dated properly by dendrochronology and hence demand specific stable isotope measuring strategies, etc.. Although the points raised here do specifically apply for the tree ring archive, some of them are important for all proxy archives of organic origin.

Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth

PubMed Central

2017-01-01

In ecology, stable isotope labelling is commonly used for tracing material transfer in trophic interactions, nutrient budgets and biogeochemical processes. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism growth and metabolism. This assumption is, however, challenged by theoretical considerations and experimental studies on kinetic isotope effects in vivo. Here, I demonstrate profound changes in life histories of the rotifer Brachionus plicatilis fed 15N-enriched algae (0.4–5.0 at%); i.e. at the enrichment levels commonly used in ecological studies. These findings support theoretically predicted effects of heavy isotope enrichment on growth, metabolism and ageing in biological systems and underline the importance of accounting for such effects when using stable isotope labelling in experimental studies. PMID:28405367

Modeling stable isotope transport in metamorphic and hydrothermal systems

NASA Astrophysics Data System (ADS)

Baumgartner, L. P.; Mueller, T.; Skora, S.; Begue, F.

2007-12-01

Stable isotopes are powerful tools for deciphering the fluid flow histories of metamorphic terrains. The nature of fluid flow, fluid sources, and fluid fluxes can be delineated in well constrained studies. Continuum mechanics models for stable isotope fluid-rock exchange were developed and used over the last three decades in an attempt to accurately interpret the signatures left behind by fluid flow in the earths crust. The efforts have been hampered by the realization that the exchange of many stable isotopes, e.g. oxygen and carbon, by intracrystalline diffusion, hence without re-organization of the crystal lattice, appears to be too slow to achieve significant exchange. This should lead to relatively flat isotopic exchange profiles on hand-, outcrop, or aureole scale. Nevertheless, isotopic fronts are typically sharp (sub mm to cm scale), when measured in the field. This has lead to the suggestion that these sharp fronts correspond to the sides of infiltration fronts, implying the data to have been collected at a high angle to the infiltration direction. Nevertheless, the fact that the oxygen and carbon fronts are located at the same place is not explained by this. A review of published carbon and oxygen data reveals that many contact aureoles show linear trends in oxygen-carbon isotope ratio diagrams for carbonate sample suits. This implies that the fluid composition infiltrating the aureoles had essentially an X(CO2) of 0.5. This is in contrast to skarn mineralogy developed, which requires a water-rich fluid, in agreement with the general notion that igneous fluids are water-rich. These and other observations indicate that the mass transport equation used for stable isotope exchange needs to be improved to model appropriately the actual isotope kinetics during fluid-rock exchange. Detailed isotope studies on systems where net transport reactions are driven by mass transport have led us to identify different exchange mechanisms, including: a) the stable isotope exchange is given by instantaneous mass balance written for the isotope during reaction; b) equilibrium precipitation of products, but slow exchange kinetics for reactants. These observations require that the reactive term in the stable isotope reactive transport equation is re-written to include the net transfer reactions, which in turn implies the solution of the transport equation for the elements driving the reaction.

ESTIMATING THE TIMING OF DIET SHIFTS USING STABLE ISOTOPES

EPA Science Inventory

Stable isotope analysis has become an important tool in studies of trophic food webs and animal feeding patterns. When animals undergo rapid dietary shifts due to migration, metamorphosis, or other reasons, the isotopic composition of their tissues begins changing to reflect tha...

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

EPA Science Inventory

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

STABLE ISOTOPES IN ECOLOGICAL STUDIES: NEW DEVELOPMENTS IN MIXING MODELS (BRAZIL)

EPA Science Inventory

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

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

EPA Science Inventory

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

Using cumulative diet data and stable isotope analysis to determine trophic position of walleye Sander vitreus in a large, complex system

USGS Publications Warehouse

Fincel, Mark J.; James, Daniel A.; Chipps, Steven R.; Davis, Blake A.

2014-01-01

Diet studies have traditionally been used to determine prey use and food web dynamics, while stable isotope analysis provides for a time-integrated approach to evaluate food web dynamics and characterize energy flow in aquatic systems. Direct comparison of the two techniques is rare and difficult to conduct in large, species rich systems. We compared changes in walleye Sander vitreus trophic position (TP) derived from paired diet content and stable isotope analysis. Individual diet-derived TP estimates were dissimilar to stable isotope-derived TP estimates. However, cumulative diet-derived TP estimates integrated from May 2001 to May 2002 corresponded to May 2002 isotope-derived estimates of TP. Average walleye TP estimates from the spring season appear representative of feeding throughout the entire previous year.

Stable isotopes in Lithuanian bioarcheological material

NASA Astrophysics Data System (ADS)

Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

2015-04-01

Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger Schutkowski. "Diet and social status during the La Tène period in Bohemia: carbon and nitrogen stable isotope analysis of bone collagen from Kutná Hora-Karlov and Radovesice." Journal of Anthropological Archaeology 24.2 (2005): 135-147. Schutkowski, Holger, et al. "Diet, status and decomposition at Weingarten: trace element and isotope analyses on early mediaeval skeletal material." Journal of Archaeological Science 26.6 (1999): 675-685. Zernitskaya, Valentina, et al. "Vegetation pattern and sedimentation changes in the context of the Lateglacial climatic events: Case study of Staroje Lake (Eastern Belarus)." Quaternary International (2014).

Stable isotopes in juvenile marine fishes and their invertebrate prey from the Thames Estuary, UK, and adjacent coastal regions

NASA Astrophysics Data System (ADS)

Leakey, Chris D. B.; Attrill, Martin J.; Jennings, Simon; Fitzsimons, Mark F.

2008-04-01

Estuaries are regarded as valuable nursery habitats for many commercially important marine fishes, potentially providing a thermal resource, refuge from predators and a source of abundant prey. Stable isotope analysis may be used to assess relative resource use from isotopically distinct sources. This study comprised two major components: (1) development of a spatial map and discriminant function model of stable isotope variation in selected invertebrate groups inhabiting the Thames Estuary and adjacent coastal regions; and (2) analysis of stable isotope signatures of juvenile bass ( Dicentrarchus labrax), sole ( Solea solea) and whiting ( Merlangius merlangus) for assessment of resource use and feeding strategies. The data were also used to consider anthropogenic enrichment of the estuary and potential energetic benefits of feeding in estuarine nursery habitat. Analysis of carbon (δ 13C), nitrogen (δ 15N) and sulphur (δ 34S) isotope data identified significant differences in the 'baseline' isotopic signatures between estuarine and coastal invertebrates, and discriminant function analysis allowed samples to be re-classified to estuarine and coastal regions with 98.8% accuracy. Using invertebrate signatures as source indicators, stable isotope data classified juvenile fishes to the region in which they fed. Feeding signals appear to reflect physiological (freshwater tolerance) and functional (mobility) differences between species. Juvenile sole were found to exist as two isotopically-discrete sub-populations, with no evidence of mixing between the two. An apparent energetic benefit of estuarine feeding was only found for sole.

Observation and modelling of stable isotopes in precipitation for midlatitude weather systems in Melbourne, Australia

NASA Astrophysics Data System (ADS)

Barras, Vaughan; Simmonds, Ian

2010-05-01

The application of stable water isotopes as tracers of moisture throughout the hydrological cycle is often hindered by the relatively coarse temporal and spatial resolution of observational data. Intensive observation periods (IOPs) of isotopes in precipitation have been valuable in this regard enabling the quantification of the effects of vapour recycling, convection, cloud top height and droplet reevaporation (Dansgaard, 1953; Miyake et al., 1968; Gedzelman and Lawrence, 1982; 1990; Pionke and DeWalle, 1992; Risi et al., 2008; 2009) and have been used as a basis to develop isotope models of varying complexity (Lee and Fung, 2008; Bony et al., 2008). This study took a unified approach combining observation and modelling of stable isotopes in precipitation in an investigation of three key circulation types that typically bring rainfall to southeastern Australia. The observational component of this study involved the establishment of the Melbourne University Network of Isotopes in Precipitation (MUNIP). MUNIP was devised to sample rainwater simultaneously at a number of collection sites across greater Melbourne to record the spatial and temporal isotopic variability of precipitation during the passage of particular events. Samples were collected at half-hourly intervals for three specific rain events referred to as (1) mixed-frontal, (2) convective, and (3) stratiform. It was found that the isotopic content for each event varied over both high and low frequencies due to influences from local changes in rain intensity and large scale rainout respectively. Of particular note was a positive relationship between deuterium excess and rainfall amount under convective conditions. This association was less well defined for stratiform rainfall. As a supplement to the data coverage of the observations, the events were simulated using a version of NCAR CAM3 running with an isotope hydrology scheme. This was done by periodically nudging the model dynamics with data from the NCEP Reanalysis (Noone, 2006). Results from the simulations showed that the model represented well the large scale evolution of vapour profiles of deuterium excess and 18O for the mixed-frontal and stratiform events. Reconstruction of air mass trajectories provided further detail of the evolution and structure of the vapour profiles revealing a convergence of air masses from different source regions for the mixed-frontal event. By combining observations and modelling in this way, much detail of the structure and isotope moisture history of the observed events was provided that would be unavailable from the sampling of precipitation alone. References Bony, S., C. Risi, and F. Vimeux (2008), Influence of convective processes on the isotopic composition (?18O and ?D) of precipitation and water vapor in the tropics: 1. Radiative-convective equilibrium and Tropical Ocean-Global Atmosphere-Coupled Ocean-Atmosphere Response (TOGA-COARE) simulations, J. Geophys. Res., 113, D19305, doi:10.1029/2008JD009942. Dansgaard, W. (1953), The abundance of 18O in atmospheric water and water vapor. Tellus, 5, 461-469. Gedzelman, S. D., and J. R. Lawrence (1982), The isotopic composition of cyclonic precipitation. J. App. Met., 21, 1385-1404. Gedzelman, S. D., and J. R. Lawrence (1990), The isotopic composition of precipitation from two extratropical cyclones, Mon. Weather Rev., 118 , 495-509. Lee, J., and I. Fung (2008), 'Amount effect' of water isotopes and quantitative analysis of post-condensation processes, Hydrol. Process., 22, 1-8. Miyake, Y., O. Matsubaya, and C. Nishihara (1968), An isotopic study on meteoric precipitation, Pap. Meteorol. Geophys., 19, 243-266. Noone, D. (2006), Isotopic composition of water vapor modeled by constraining global climate simulations with reanalyses, in Research activities in atmospheric and oceanic modeling, J. Côté (ed.), Report No. 36, WMO/TD-No. 1347, p. 2.37-2.38. Pionke, H. B., and D. R. DeWalle (1992), Intra- and inter-storm 18O trends for selected rainstorms in Pennsylvania. J. Hydrol., 138, 131-143. Risi, C., S. Bony, and F. Vimeux (2008), Influence of convective processes on the isotopic composition (?18O and ?D) of precipitation and water vapor in the tropics: 2. Physical interpretation of the amount effect. J. Geophys. Res., 113, D19306, doi:10.1029/2008JD009943. Risi, C., S. Bony, F. Vimeux, M. Chong, and L. Descroix (2009), Evolution of the water stable isotopic composition of the rain sampled along Sahelian squall lines, Q. J. Roy. Meteor. Soc., doi:10.1002/qj.485, (in press).

Seeking excellence: An evaluation of 235 international laboratories conducting water isotope analyses by isotope-ratio and laser-absorption spectrometry.

PubMed

Wassenaar, L I; Terzer-Wassmuth, S; Douence, C; Araguas-Araguas, L; Aggarwal, P K; Coplen, T B

2018-03-15

Water stable isotope ratios (δ 2 H and δ 18 O values) are widely used tracers in environmental studies; hence, accurate and precise assays are required for providing sound scientific information. We tested the analytical performance of 235 international laboratories conducting water isotope analyses using dual-inlet and continuous-flow isotope ratio mass spectrometers and laser spectrometers through a water isotope inter-comparison test. Eight test water samples were distributed by the IAEA to international stable isotope laboratories. These consisted of a core set of five samples spanning the common δ-range of natural waters, and three optional samples (highly depleted, enriched, and saline). The fifth core sample contained unrevealed trace methanol to assess analyst vigilance to the impact of organic contamination on water isotopic measurements made by all instrument technologies. For the core and optional samples ~73 % of laboratories gave acceptable results within 0.2 ‰ and 1.5 ‰ of the reference values for δ 18 O and δ 2 H, respectively; ~27 % produced unacceptable results. Top performance for δ 18 O values was dominated by dual-inlet IRMS laboratories; top performance for δ 2 H values was led by laser spectrometer laboratories. Continuous-flow instruments yielded comparatively intermediate results. Trace methanol contamination of water resulted in extreme outlier δ-values for laser instruments, but also affected reactor-based continuous-flow IRMS systems; however, dual-inlet IRMS δ-values were unaffected. Analysis of the laboratory results and their metadata suggested inaccurate or imprecise performance stemmed mainly from skill- and knowledge-based errors including: calculation mistakes, inappropriate or compromised laboratory calibration standards, poorly performing instrumentation, lack of vigilance to contamination, or inattention to unreasonable isotopic outcomes. To counteract common errors, we recommend that laboratories include 1-2 'known' control standards in all autoruns; laser laboratories should screen each autorun for spectral contamination; and all laboratories should evaluate whether derived d-excess values are realistic when both isotope ratios are measured. Combined, these data evaluation strategies should immediately inform the laboratory about fundamental mistakes or compromised samples. Copyright © 2018 John Wiley & Sons, Ltd.

Seeking excellence: An evaluation of 235 international laboratories conducting water isotope analyses by isotope-ratio and laser-absorption spectrometry

USGS Publications Warehouse

Wassenaar, L. I.; Terzer-Wassmuth, S.; Douence, C.; Araguas-Araguas, L.; Aggarwal, P. K.; Coplen, Tyler B.

2018-01-01

RationaleWater stable isotope ratios (δ2H and δ18O values) are widely used tracers in environmental studies; hence, accurate and precise assays are required for providing sound scientific information. We tested the analytical performance of 235 international laboratories conducting water isotope analyses using dual-inlet and continuous-flow isotope ratio mass spectrometers and laser spectrometers through a water isotope inter-comparison test.MethodsEight test water samples were distributed by the IAEA to international stable isotope laboratories. These consisted of a core set of five samples spanning the common δ-range of natural waters, and three optional samples (highly depleted, enriched, and saline). The fifth core sample contained unrevealed trace methanol to assess analyst vigilance to the impact of organic contamination on water isotopic measurements made by all instrument technologies.ResultsFor the core and optional samples ~73 % of laboratories gave acceptable results within 0.2 ‰ and 1.5 ‰ of the reference values for δ18O and δ2H, respectively; ~27 % produced unacceptable results. Top performance for δ18O values was dominated by dual-inlet IRMS laboratories; top performance for δ2H values was led by laser spectrometer laboratories. Continuous-flow instruments yielded comparatively intermediate results. Trace methanol contamination of water resulted in extreme outlier δ-values for laser instruments, but also affected reactor-based continuous-flow IRMS systems; however, dual-inlet IRMS δ-values were unaffected.ConclusionsAnalysis of the laboratory results and their metadata suggested inaccurate or imprecise performance stemmed mainly from skill- and knowledge-based errors including: calculation mistakes, inappropriate or compromised laboratory calibration standards, poorly performing instrumentation, lack of vigilance to contamination, or inattention to unreasonable isotopic outcomes. To counteract common errors, we recommend that laboratories include 1–2 'known' control standards in all autoruns; laser laboratories should screen each autorun for spectral contamination; and all laboratories should evaluate whether derived d-excess values are realistic when both isotope ratios are measured. Combined, these data evaluation strategies should immediately inform the laboratory about fundamental mistakes or compromised samples.

Golan Heights Groundwater Systems: Separation By REE+Y And Stable Isotopes

NASA Astrophysics Data System (ADS)

Siebert, C.; Geyer, S.; Knoeller, K.; Roediger, T.; Weise, S.; Dulski, P.; Moeller, P.; Guttman, J.

2008-12-01

In a semi-arid to arid country like Israel, all freshwater resources are under (over-) utilization. Particularly, the Golan Heights rank as one of the most important extraction areas of groundwater of good quality and quantity. Additionally the mountain range feed to a high degree the most important freshwater reservoir of Israel, the Sea of Galilee. Hence, knowing the sources and characters of the Golan Heights groundwater systems is an instantaneous demand regarding sustainable management and protection. Within the "German-Israeli-Jordanian-Palestinian Joint Research Program for the Sustainable Utilisation of Aquifer Systems", hundreds of water samples were taken from all over the Jordan-Dead Sea rift-system to understand groundwater flow-systems and salinisation. For that purpose, each sample was analysed for major and minor ions, rare earth elements including yttrium (REY) and stable isotopes of water (d18O, d2H). The REY distribution in groundwater is established during infiltration by the first water-rock interaction and consequently reflects the leachable components of sediments and rocks of the recharge area. In well- developed flow-systems, REY are adsorbed onto pore surfaces are in equilibrium with the percolating groundwater, even if the lithology changes (e.g. inter-aquifer flow). Thus, groundwater sampled from wells and springs still show the REY distribution pattern established in the recharge area. Since high temperatures do not occur in Golan Heights, d2H and d18O are less controlled by water-rock interaction than by climatic and geomorphological factors at the time of replenishment. Applying the REY signature as a grouping criterion of groundwaters, d18O vs. d2H plots yield a new dimension in interpreting isotope data. The combined use of hydrochemical and isotopic methods enabled us to contain the areas of replenishment and the flow-paths of all investigated groundwater in the Golan Heights. Despite location, salinity or temperature of spring or well waters, stable isotopes showed, that the main area of recharge is the elevated Hermon-Massif, with high annually precipitation amounts. The major element composition of fresh water well Alonei HaBashan 3, situated in the basaltic Upper Golan Heights, is defined by a pre-Neogenic limy aquifer and the contact to basalts. However, REY pattern refer to a calcareous infiltration area. Stable isotope signatures are lighter than in the recharge of comparable elevated Upper Galilee. Further to the south, in the Yarmouk gorge hot Mezar springs occur, which show stable isotope signatures even lighter than in water of Alonei Habshan 3. Both, REY pattern and hydrochemistry show infiltration into and contact to the Sr-rich limestone aquifer of the Mt. Scopus group. That adds up to an infiltration area some 50 km to the north, the nearest elevated area where carbonates crop out. Nearby Mezar, hot Hammat Gader springs occur, which show comparable isotopic signatures and hydrochemical composition. However, the REY-patterns indicate infiltration in basalts. By means of those three examples we could show, that the use of a combined hydrochemical and isotopic approach reveals complex and large-scale groundwater infiltration- and flow-systems much better than a focused view on a specific band of elements.

The Role of Naturally Occurring Stable Isotopes in Mass Spectrometry, Part II: The Instrumentation

PubMed Central

Bluck, Les; Volmer, Dietrich A.

2013-01-01

In the second instalment of this tutorial, the authors explain the instrumentation for measuring naturally occurring stable isotopes, specifically the magnetic sector mass spectrometer. This type of instrument remains unrivalled in its performance for isotope ratio mass spectrometry (IRMS) and the reader is reminded of its operation and its technical advantages for isotope measurements. PMID:23772101

Use of stable sulphur isotopes to monitor directly the behaviour of sulphur in coal during thermal desulphurization

USGS Publications Warehouse

Liu, Chao-Li; Hackley, Keith C.; Coleman, D.D.

1987-01-01

A method has been developed using stable sulphur isotope analyses to monitor the behaviour of sulphur forms in a coal during thermal desulphurization. In this method, the natural stable isotopic composition of the pyritic and organic sulphur in coal is used as a tracer to follow their mobility during the desulphurization process. This tracer method is based on the fact that the isotopic compositions of pyritic and organic sulphur are significantly different in some coals. Isotopic results of pyrolysis experiments at temperatures ranging from 350 to 750 ??C indicate that the sulphur released with the volatiles is predominantly organic sulphur. The pyritic sulphur is evolved in significant quantities only when pyrolysis temperatures exceed 500 ??C. The presence of pyrite seems to have no effect on the amount of organic sulphur evolved during pyrolysis. The chemical and isotopic mass balances achieved from three different samples of the Herrin (No. 6) coal of the Illinois Basin demonstrate that this stable isotope tracer method is quantitative. The main disadvantage of this tracing technique is that not all coals contain isotopically distinct organic and pyritic sulphur. ?? 1987.

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

Carbon Stable Isotopes as Indicators of Coastal Eutrophication

EPA Science Inventory

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

Stable Isotope Tracers of Process in Great Lakes Food Webs

EPA Science Inventory

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

SOURCE PARTITIONING USING STABLE ISOTOPES: COPING WITH TOO MANY SOURCES

EPA Science Inventory

Stable isotopes are increasingly being used as tracers in environmental studies. One application is to use isotopic ratios to quantitatively determine the proportional contribution of several sources to a mixture, such as the proportion of various pollution sources in a waste st...

USE OF STABLE ISOTOPES IN ENVIRONMENTAL AND FORENSIC GEOCHEMISTRY STUDIES

EPA Science Inventory

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

Growth of the European abalone ( Haliotis tuberculata L.) in situ: Seasonality and ageing using stable oxygen isotopes

NASA Astrophysics Data System (ADS)

Roussel, Sabine; Huchette, Sylvain; Clavier, Jacques; Chauvaud, Laurent

2011-02-01

The ormer, Haliotis tuberculata is the only European abalone species commercially exploited. The determination of growth and age in the wild is an important tool for fisheries and aquaculture management. However, the ageing technique used in the past in the field is unreliable. The stable oxygen isotope composition ( 18O/ 16O) of the shell depends on the temperature and oxygen isotope composition of the ambient sea water. The stable oxygen isotope technique, developed to study paleoclimatological changes in shellfish, was applied to three H. tuberculata specimens collected in north-west Brittany. For the specimens collected, the oxygen isotope ratios of the shell reflected the seasonal cycle in the temperature. From winter-to-winter cycles, estimates of the age and the annual growth increment, ranging from 13 to 55 mm per year were obtained. This study shows that stable oxygen isotopes can be a reliable tool for ageing and growth studies of this abalone species in the wild, and for validating other estimates.

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.

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

EPA Science Inventory

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

Stable Isotopes Reveal Nitrogen Loading to Lake Tanganyika from Remote Shoreline Villages

NASA Astrophysics Data System (ADS)

Kelly, Brianne; Mtiti, Emmanuel; McIntyre, Peter B.; Vadeboncoeur, Yvonne

2017-02-01

Access to safe water is an ongoing challenge in rural areas in Tanzania where communities often lack access to improved sanitation. Methods to detect contamination of surface water bodies, such as monitoring nutrient concentrations and bacterial counts, are time consuming and results can be highly variable in space and time. On the northeast shore of Lake Tanganyika, Tanzania, the low population density coupled with the high potential for dilution in the lake necessitates the development of a sensitive method for detecting contamination in order to avoid human health concerns. We investigated the potential use of nitrogen and carbon stable isotopes of snail tissues to detect anthropogenic nutrient loading along the northeast shore of Lake Tanganyika. δ15N of snails was positively related to human population size in the nearest village, but only for villages with >4000 inhabitants. The areal footprint of villages within their watershed was also significantly correlated with snail δ15N, while agricultural land use and natural vegetation were not. Dissolved nutrient concentrations were not significantly different between village and reference sites. Our results indicate that nitrogen isotopes provide a sensitive index of local nutrient loading that can be used to monitor contamination of oligotrophic aquatic environments with low surrounding population densities.

Stable isotope analysis of energy dynamics in aquatic ecosystems suggests trophic shifts following severe wildfire

NASA Astrophysics Data System (ADS)

Martens, A. M.; Silins, U.; Bladon, K. D.; Williams, C.; Wagner, M. J.; Luchkow, E.

2015-12-01

Wildfire alters landscapes and can have significant impacts on stream ecosystems. The 2003 Lost Creek wildfire was one of the most severe on Alberta's eastern rocky mountain slopes, resulting in elevated sediment production and nutrient (phosphorus, nitrogen, and carbon) export in impacted streams. These resulted in increased algal productivity and macroinvertebrate abundance and diversity, and as a result, fish in watersheds draining wildfire affected catchments were larger than those in the same age class from reference (unburned) watersheds. In the present investigation, stable isotope analysis of C and N was utilized to evaluate ecosystem energy dynamics and describe trophic relationships in those watersheds. Aquatic invertebrates from burned catchments showed enrichment in δ13C and δ15N relative to algae suggesting a reliance on algae (autochthony) as a primary source of energy. Invertebrates from unburned systems were depleted in δ13C relative to algae indicating reliance on allochthonous or terrestrial primary energy sources. Preliminary analysis of δ15N in macroinvertebrates showed slight enrichment in burned catchments suggesting a trophic shift. More comprehensive macroinvertebrate sampling and identification has been conducted; isotopic analysis will provide greater resolution of how specific families within feeding guilds have been affected by wildfire. This will provide more robust insights into how wildfires may impact stream ecology in mountain environments.

How Will Sea Ice Loss Affect the Greenland Ice Sheet? On the Puzzling Features of Greenland Ice-Core Isotopic Composition

NASA Technical Reports Server (NTRS)

Pausata, Francesco S. R.; Legrande, Allegra N.; Roberts, William H. G.

2016-01-01

The modern cryosphere, Earth's frozen water regime, is in fast transition. Greenland ice cores show how fast theses changes can be, presenting evidence of up to 15 C warming events over timescales of less than a decade. These events, called Dansgaard/Oeschger (D/O) events, are believed to be associated with rapid changes in Arctic sea ice, although the underlying mechanisms are still unclear. The modern demise of Arctic sea ice may, in turn, instigate abrupt changes on the Greenland Ice Sheet. The Arctic Sea Ice and Greenland Ice Sheet Sensitivity (Ice2Ice Chttps://ice2ice.b.uib.noD) initiative, sponsored by the European Research Council, seeks to quantify these past rapid changes to improve our understanding of what the future may hold for the Arctic. Twenty scientists gathered in Copenhagen as part of this initiative to discuss the most recent observational, technological, and model developments toward quantifying the mechanisms behind past climate changes in Greenland. Much of the discussion focused on the causes behind the changes in stable water isotopes recorded in ice cores. The participants discussed sources of variability for stable water isotopes and framed ways that new studies could improve understanding of modern climate. The participants also discussed how climate models could provide insights into the relative roles of local and nonlocal processes in affecting stable water isotopes within the Greenland Ice Sheet. Presentations of modeling results showed how a change in the source or seasonality of precipitation could occur not only between glacial and modern climates but also between abrupt events. Recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. Further, indications from recent fieldwork campaigns illustrate an important role of stable isotopes in atmospheric vapor and diffusion in the final stable isotope signal in ice. This feature complicates the quantitative interpretation of ice core signals but also makes the stable ice isotope signal a more robust regional indicator of climate, speakers noted. Meeting participants agreed that to further our understanding of these relationships, we need more process-focused field and laboratory campaigns.

Recent developments in application of stable isotope analysis on agro-product authenticity and traceability.

PubMed

Zhao, Yan; Zhang, Bin; Chen, Gang; Chen, Ailiang; Yang, Shuming; Ye, Zhihua

2014-02-15

With the globalisation of agro-product markets and convenient transportation of food across countries and continents, the potential for distribution of mis-labelled products increases accordingly, highlighting the need for measures to identify the origin of food. High quality food with identified geographic origin is a concern not only for consumers, but also for agriculture farmers, retailers and administrative authorities. Currently, stable isotope ratio analysis in combination with other chemical methods gradually becomes a promising approach for agro-product authenticity and traceability. In the last five years, a growing number of research papers have been published on tracing agro-products by stable isotope ratio analysis and techniques combining with other instruments. In these reports, the global variety of stable isotope compositions has been investigated, including light elements such as C, N, H, O and S, and heavy isotopes variation such as Sr and B. Several factors also have been considered, including the latitude, altitude, evaporation and climate conditions. In the present paper, an overview is provided on the authenticity and traceability of the agro-products from both animal and plant sources by stable isotope ratio analysis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Examination of an Oligocene Lacustrine Ecosystem Using C and N Stable Isotopes

NASA Astrophysics Data System (ADS)

Schweizer, M. K.; Wooller, M. J.; Toporski, J.; Fogel, M.; Steele, A.

2003-12-01

Stable isotopes of C and N are used to reconstruct the fossil Oligocene (25.8Ma) ecosystem at Lake Enspel, Westerwald, Germany. Enspel was a steep-sided, deep maar lake with anoxic bottom waters. Upon dying, terrestrial and aquatic organisms sank into the sediment where they were colonized by bacteria. These bacteria quickly became fossilized, preserving morphological detail and large amounts of organic matter from the original macroorganism. Carbon and nitrogen are sufficiently preserved in these fossils to permit stable isotope analysis. Stable isotopic signatures identify several trophic levels, including primary producers (terrigenous and aquatic plants, diatoms), primary consumers (tadpoles, some insects), and secondary consumers (carnivores such as fish). Primary producers are associated with depleted d13C and d15N values, primary consumers such as flies are one trophic shift higher, and fish are another shift higher. Signatures for the fish species show heavy-isotope enrichment correlated with increasing length, indicating an increasingly carnivorous diet. This study marks the first attempt to reconstruct a complete fossil ecosystem using stable isotope analysis, and confirms that techniques used to study modern food webs can be applied to extinct webs as well.

Stable Isotope Ratios as Biomarkers of Diet for Health Research

PubMed Central

O’Brien, Diane M.

2016-01-01

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

Dipole response of neutron-rich Sn isotopes

NASA Astrophysics Data System (ADS)

Klimkiewicz, A.; Adrich, P.; Boretzky, K.; Fallot, M.; Aumann, T.; Cortina-Gil, D.; Datta Pramanik, U.; Elze, Th. W.; Emling, H.; Geissel, H.; Hellstroem, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Leifels, Y.; Nociforo, C.; Palit, R.; Simon, H.; Surowka, G.; Sümmerer, K.; Typel, S.; Walus, W.

2007-05-01

The neutron-rich isotopes 129-133Sn were studied in a Coulomb excitation experiment at about 500 AMeV using the FRS-LAND setup at GSI. From the exclusive measurement of all projectile-like particles following the excitation and decay of the projectile in a high-Z target, the energy differential cross section can be extracted. At these beam energies dipole transitions are dominating, and within the semi-classical approach the Coulomb excitation cross sections can be transformed into photoabsorption cross sections. In contrast to stable Sn nuclei, a substantial fraction of dipole strength is observed at energies below the giant dipole resonance (GDR). For 130Sn and 132Sn this strength is located in a peak-like structure around 10 MeV excitation energy and exhibits a few percent of the Thomas-Reiche Kuhn (TRK) sum-rule strength. Several calculations predict the appearance of dipole strength at low excitation energies in neutron-rich nuclei. This low-lying strength is often referred to as pygmy dipole resonance (PDR) and, in a macroscopic picture, is discussed in terms of a collective oscillation of excess neutrons versus the core nucleons. Moreover, a sharp rise is observed at the neutron separation threshold around 5 MeV for the odd isotopes. A possible contribution of 'threshold strength', which can be described within the direct-breakup model is discussed. The results for the neutron-rich Sn isotopes are confronted with results on stable nuclei investigated in experiments using real photons.

Stable isotopic variation in tropical forest plants for applications in primatology.

PubMed

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

2016-10-01

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

Inferring the source of evaporated waters using stable H and O isotopes

EPA Science Inventory

Stable isotope ratios of H and O are widely used to identify the source of water, e.g., in aquifers, river runoff, soils, plant xylem, and plant-based beverages. In situations where the sampled water is partially evaporated, its isotope values will have evolved along an evaporati...

Development and Validation of a Rapid (13)C6-Glucose Isotope Dilution UPLC-MRM Mass Spectrometry Method for Use in Determining System Accuracy and Performance of Blood Glucose Monitoring Devices.

PubMed

Matsunami, Risë K; Angelides, Kimon; Engler, David A

2015-05-18

There is currently considerable discussion about the accuracy of blood glucose concentrations determined by personal blood glucose monitoring systems (BGMS). To date, the FDA has allowed new BGMS to demonstrate accuracy in reference to other glucose measurement systems that use the same or similar enzymatic-based methods to determine glucose concentration. These types of reference measurement procedures are only comparative in nature and are subject to the same potential sources of error in measurement and system perturbations as the device under evaluation. It would be ideal to have a completely orthogonal primary method that could serve as a true standard reference measurement procedure for establishing the accuracy of new BGMS. An isotope-dilution liquid chromatography/mass spectrometry (ID-UPLC-MRM) assay was developed using (13)C6-glucose as a stable isotope analogue to specifically measure glucose concentration in human plasma, and validated for use against NIST standard reference materials, and against fresh isolates of whole blood and plasma into which exogenous glucose had been spiked. Assay performance was quantified to NIST-traceable dry weight measures for both glucose and (13)C6-glucose. The newly developed assay method was shown to be rapid, highly specific, sensitive, accurate, and precise for measuring plasma glucose levels. The assay displayed sufficient dynamic range and linearity to measure across the range of both normal and diabetic blood glucose levels. Assay performance was measured to within the same uncertainty levels (<1%) as the NIST definitive method for glucose measurement in human serum. The newly developed ID UPLC-MRM assay can serve as a validated reference measurement procedure to which new BGMS can be assessed for glucose measurement performance. © 2015 Diabetes Technology Society.

Development and Validation of a Rapid 13C6-Glucose Isotope Dilution UPLC-MRM Mass Spectrometry Method for Use in Determining System Accuracy and Performance of Blood Glucose Monitoring Devices

PubMed Central

Matsunami, Risë K.; Angelides, Kimon; Engler, David A.

2015-01-01

Background: There is currently considerable discussion about the accuracy of blood glucose concentrations determined by personal blood glucose monitoring systems (BGMS). To date, the FDA has allowed new BGMS to demonstrate accuracy in reference to other glucose measurement systems that use the same or similar enzymatic-based methods to determine glucose concentration. These types of reference measurement procedures are only comparative in nature and are subject to the same potential sources of error in measurement and system perturbations as the device under evaluation. It would be ideal to have a completely orthogonal primary method that could serve as a true standard reference measurement procedure for establishing the accuracy of new BGMS. Methods: An isotope-dilution liquid chromatography/mass spectrometry (ID-UPLC-MRM) assay was developed using 13C6-glucose as a stable isotope analogue to specifically measure glucose concentration in human plasma, and validated for use against NIST standard reference materials, and against fresh isolates of whole blood and plasma into which exogenous glucose had been spiked. Assay performance was quantified to NIST-traceable dry weight measures for both glucose and 13C6-glucose. Results: The newly developed assay method was shown to be rapid, highly specific, sensitive, accurate, and precise for measuring plasma glucose levels. The assay displayed sufficient dynamic range and linearity to measure across the range of both normal and diabetic blood glucose levels. Assay performance was measured to within the same uncertainty levels (<1%) as the NIST definitive method for glucose measurement in human serum. Conclusions: The newly developed ID UPLC-MRM assay can serve as a validated reference measurement procedure to which new BGMS can be assessed for glucose measurement performance. PMID:25986627

18O-labeled proteome reference as global internal standards for targeted quantification by selected reaction monitoring-mass spectrometry.

PubMed

Kim, Jong-Seo; Fillmore, Thomas L; Liu, Tao; Robinson, Errol; Hossain, Mahmud; Champion, Boyd L; Moore, Ronald J; Camp, David G; Smith, Richard D; Qian, Wei-Jun

2011-12-01

Selected reaction monitoring (SRM)-MS is an emerging technology for high throughput targeted protein quantification and verification in biomarker discovery studies; however, the cost associated with the application of stable isotope-labeled synthetic peptides as internal standards can be prohibitive for screening a large number of candidate proteins as often required in the preverification phase of discovery studies. Herein we present a proof of concept study using an (18)O-labeled proteome reference as global internal standards (GIS) for SRM-based relative quantification. The (18)O-labeled proteome reference (or GIS) can be readily prepared and contains a heavy isotope ((18)O)-labeled internal standard for every possible tryptic peptide. Our results showed that the percentage of heavy isotope ((18)O) incorporation applying an improved protocol was >99.5% for most peptides investigated. The accuracy, reproducibility, and linear dynamic range of quantification were further assessed based on known ratios of standard proteins spiked into the labeled mouse plasma reference. Reliable quantification was observed with high reproducibility (i.e. coefficient of variance <10%) for analyte concentrations that were set at 100-fold higher or lower than those of the GIS based on the light ((16)O)/heavy ((18)O) peak area ratios. The utility of (18)O-labeled GIS was further illustrated by accurate relative quantification of 45 major human plasma proteins. Moreover, quantification of the concentrations of C-reactive protein and prostate-specific antigen was illustrated by coupling the GIS with standard additions of purified protein standards. Collectively, our results demonstrated that the use of (18)O-labeled proteome reference as GIS provides a convenient, low cost, and effective strategy for relative quantification of a large number of candidate proteins in biological or clinical samples using SRM.

Light Stable Isotopic Compositions of Enriched Mantle Sources: Resolving the Dehydration Paradox

NASA Astrophysics Data System (ADS)

Dixon, J. E.; Bindeman, I. N.; Kingsley, R. H.

2017-12-01

An outstanding puzzle in mantle geochemistry has been the origin and evolution of Earth's volatile components. The "dehydration paradox" refers to the following conundrum. Mantle compositions for some enriched mid-ocean ridge (MORB) and ocean island (OIB) basalts basalts require involvement of a mostly dehydrated slab component to explain the trace element ratios and radiogenic isotopic compositions, but a fully hydrated slab component to explain the stable isotopic compositions. Volatile and stable isotopic data on enriched MORB show a diversity of enriched components. Pacific PREMA-type basalts (H2O/Ce = 215 ± 30, δDSMOW = -45 ± 5 ‰) are similar to those in the north Atlantic (H2O/Ce = 220 ± 30; δDSMOW = -30 to -40 ‰). Basalts with EM-type signatures have regionally variable volatile compositions. North Atlantic EM-type basalts are wetter (H2O/Ce = 330 ± 30) and have isotopically heavier hydrogen (δDSMOW = -57 ± 5 ‰) than north Atlantic MORB. South Atlantic EM-type basalts are damp (H2O/Ce = 120 ± 10) with intermediate δDSMOW (-68 ± 2 ‰), similar to dDSMOW for Pacific MORB. North EPR EM-type basalts are dry (H2O/Ce = 110 ± 20) and isotopically light (δDSMOW = -94 ± 3 ‰). Boron and lithium isotopic ratios parallel the trends observed for dDSMOW. A multi-stage metasomatic and melting model accounts for the origin of the enriched components by extending the subduction factory concept down through the mantle transition zone, with slab temperature a key variable. The dehydration paradox is resolved by decoupling of volatiles from lithophile elements, reflecting primary dehydration of the slab followed by secondary rehydration and re-equilibration by fluids derived from subcrustal hydrous phases (e.g., antigorite) in cooler, deeper parts of the slab. The "expanded subduction factory" model includes melting at several key depths, including 1) 180 to 280 km, where EM-type mantle compositions are generated above slabs with average to hot thermal profiles by addition of <1% carbonated sediment-derived supercritical fluids/melts to depleted asthenospheric or subcontinental lithospheric mantle, and 2) 410 to 660 km, where PREMA-type mantle sources are generated, above slabs with average to cool thermal profiles, by addition of <1% carbonated eclogite ± sediment-derived supercritical fluids to depleted mantle.

Chemical Sample Processing for Combined Selenium Isotope and Selenium-Tellurium Elemental Investigation of the Earth's Igneous Reservoirs

NASA Astrophysics Data System (ADS)

Yierpan, Aierken; König, Stephan; Labidi, Jabrane; Kurzawa, Timon; Babechuk, Michael G.; Schoenberg, Ronny

2018-02-01

The redox-sensitive, chalcophile, and volatile Se stable isotope system offers new perspectives to investigate the origin and evolution of terrestrial volatiles and the roles of magmatic and recycling processes in the development of the redox contrast between Earth's reservoirs. Selenium isotope systematics become more robust in a well-constrained petrogenetic context as can be inferred from Se-Te elemental signatures of sulfides and igneous rocks. In this study, we present a high-yield chemical sample processing method that allows the determination of Se-Te concentrations and Se isotope composition from the same sample digest of silicate rocks by hydride generation isotope dilution (ID) quadrupole inductively coupled plasma mass spectrometry (ICP-MS) and double spike (DS) multicollector (MC)-ICP-MS, respectively. Our procedure yields ˜80% Se-Te recoveries with quantitative separation of relevant interfering elements such as Ge and HG-buffering metals. Replicate analyses of selected international reference materials yield uncertainties better than 0.11‰ (2 s.d.) on δ82/76Se and 3% (r.s.d.) on Se concentration for DS MC-ICP-MS determinations for as low as ˜10 ng sample Se. The precision of Se-Te concentration measurements by ID ICP-MS is better than 3% and 5% (r.s.d.) for total amounts of ˜0.5-1 ng Se and ˜0.2-0.5 ng Te, respectively. The basaltic reference materials have variable Se-Te contents, but their δ82/76Se values are rather uniform (on average 0.23 ± 0.14‰; 2 s.d.) and different from the chondritic value. This altogether provides the methodology and potential to extend the limited data set of coupled Se isotope and Se-Te elemental systematics of samples relevant to study the terrestrial igneous inventory.

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.

Aquaculture disturbance impacts the diet but not ecological linkages of a ubiquitous predatory fish

USGS Publications Warehouse

McPeek, Kathleen C.; McDonald, P. Sean; VanBlaricom, Glenn

2015-01-01

Aquaculture operations are a frequent and prominent cause of anthropogenic disturbance to marine and estuarine communities and may alter species composition and abundance. However, little is known about how such disturbances affect trophic linkages or ecosystem functions. In Puget Sound, Washington, aquaculture of the Pacific geoduck clam (Panopea generosa) is increasing and involves placing nets and polyvinyl chloride (PVC) tubes in intertidal areas to protect juvenile geoducks from predators. Initial studies of the structured phase of the farming cycle have documented limited impacts on the abundance of some species. To examine the effect of geoduck aquaculture on ecological linkages, the trophic relationships of a local ubiquitous consumer, Pacific staghorn sculpin (Leptocottus armatus), to its invertebrate prey were compared between geoduck aquaculture sites and nearby reference areas with no aquaculture. Mark-recapture data indicated that sculpin exhibit local site fidelity to cultured and reference areas. The stomach contents of sculpin and stable isotope signatures of sculpin and their prey were examined to study the trophic ecology of cultured and reference areas. Results showed that the structured phase of geoduck aquaculture initiated some changes to staghorn sculpin ecology, as reflected in sculpin diet through stomach content analysis. However, carbon and nitrogen stable isotopes revealed that the general food web function of sculpin remained unchanged. The source of carbon at the base of the food web and the trophic position of sculpin were not impacted by geoduck aquaculture. The study has important implications for geoduck aquaculture management and will inform regulatory decisions related to shellfish aquaculture policy.

Application of stable isotope ratio analysis for biodegradation monitoring in groundwater

USGS Publications Warehouse

Hatzinger, Paul B.; Böhlke, John Karl; Sturchio, Neil C.

2013-01-01

Stable isotope ratio analysis is increasingly being applied as a tool to detect, understand, and quantify biodegradation of organic and inorganic contaminants in groundwater. An important feature of this approach is that it allows degradative losses of contaminants to be distinguished from those caused by non-destructive processes such as dilution, dispersion, and sorption. Recent advances in analytical techniques, and new approaches for interpreting stable isotope data, have expanded the utility of this method while also exposing complications and ambiguities that must be considered in data interpretations. Isotopic analyses of multiple elements in a compound, and multiple compounds in the environment, are being used to distinguish biodegradative pathways by their characteristic isotope effects. Numerical models of contaminant transport, degradation pathways, and isotopic composition are improving quantitative estimates of in situ contaminant degradation rates under realistic environmental conditions.

Stable isotopes (carbon, nitrogen, sulfur), diet, and anthropometry in urban Colombian women: investigating socioeconomic differences.

PubMed

Bender, Richard L; Dufour, Darna L; Valenzuela, Luciano O; Cerling, Thure E; Sponheimer, Matt; Reina, Julio C; Ehleringer, James R

2015-01-01

We conducted stable isotope and dietary analyses of women from higher and lower socioeconomic status (SES) groups in Cali, Colombia. The objectives were to test between-group differences in stable isotope, dietary, and anthropometric characteristics, and to evaluate relationships between diet and stable isotope values. Hair samples from 38 women (mean age 33.4) from higher and lower SES groups were analyzed for δ(13) C, δ(15) N, and δ(34) S values. Dietary intake was assessed via 24-h recalls. Anthropometric variables measured were body mass index, five body circumferences, and six skinfold thicknesses. Mean δ(13) C and δ(15) N values of the higher SES group (-16.4 and 10.3‰) were significantly greater than those of the lower SES group (-17.2 and 9.6‰; P < 0.01), but mean δ(34) S values did not differ significantly between groups (higher SES: 4.6‰; lower SES: 5.1‰). The higher SES group consumed a greater percentage of protein than the lower SES group (14% vs. 12% of energy; P = 0.03), but the groups did not differ in other dietary characteristics or in anthropometric characteristics. δ(13) C, δ(15) N, and δ(34) S values were not correlated with intake of the dietary items predicted (sugars, animal-source protein, and marine foods, respectively). The lower SES group was more variable in all three stable isotope values (P < 0.05), mirroring a trend toward greater dietary variability in this group. Stable isotope values revealed a difference between SES groups that was not explained by the dietary data. The relationship between diet and stable isotope composition is complex. © 2014 Wiley Periodicals, Inc.

Stable isotope tracers and exercise physiology: past, present and future.

PubMed

Wilkinson, Daniel J; Brook, Matthew S; Smith, Kenneth; Atherton, Philip J

2017-05-01

Stable isotope tracers have been invaluable assets in physiological research for over 80 years. The application of substrate-specific stable isotope tracers has permitted exquisite insight into amino acid, fatty-acid and carbohydrate metabolic regulation (i.e. incorporation, flux, and oxidation, in a tissue-specific and whole-body fashion) in health, disease and response to acute and chronic exercise. Yet, despite many breakthroughs, there are limitations to 'substrate-specific' stable isotope tracers, which limit physiological insight, e.g. the need for intravenous infusions and restriction to short-term studies (hours) in controlled laboratory settings. In recent years significant interest has developed in alternative stable isotope tracer techniques that overcome these limitations, in particular deuterium oxide (D 2 O or heavy water). The unique properties of this tracer mean that through oral administration, the turnover and flux through a number of different substrates (muscle proteins, lipids, glucose, DNA (satellite cells)) can be monitored simultaneously and flexibly (hours/weeks/months) without the need for restrictive experimental control. This makes it uniquely suited for the study of 'real world' human exercise physiology (amongst many other applications). Moreover, using D 2 O permits evaluation of turnover of plasma and muscle proteins (e.g. dynamic proteomics) in addition to metabolomics (e.g. fluxomics) to seek molecular underpinnings, e.g. of exercise adaptation. Here, we provide insight into the role of stable isotope tracers, from substrate-specific to novel D 2 O approaches, in facilitating our understanding of metabolism. Further novel potential applications of stable isotope tracers are also discussed in the context of integration with the snowballing field of 'omic' technologies. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

H, C, O, and N stable isotopes to decipher climate feedbacks in a mountainous watershed (East River, Colorado)

NASA Astrophysics Data System (ADS)

Bill, M.; Conrad, M. E.; Beller, H. R.; Bouskill, N.; Brodie, E.; Brown, W.; Carroll, R. W. H.; Kim, Y.; Nico, P. S.; Sorensen, P. O.; Tokunaga, T. K.; Wan, J.; Williams, K. H.

2017-12-01

Temperature and precipitation variability in response to climate change affects water cycling of a watershed and can potentially impact water quality, water availability, elemental and molecular fluxes, and biogeochemical processes. Here we report the application of light stable isotopic analysis to a large multidisciplinary project addressing watershed function. The study area is charaterized by a snow-dominated headwater catchment of the Colorado River (East River, Colorado). We are measuring H, C, O, and N stable isotopes in an effort to differentiate natural and climate induced perturbations to the hydrologic cycle on C and N cycling in a moutainous watershed. Water H and O stable isotopes of rain, snow, ground and surface water are being used to constrain source contributions to streamflow. H and O isotopes of water together with elemental concentations were used in end-member mixing analysis (EMMA) to chararacterize and quantify downstream flow. Results indicate runoff is dominated by snowmelt (66±13%) and to a lessor extent groundwater (26±11%) with sources moving toward near equal contributions during baseflow (45%). We are also using C and N stable isotopes in conjunction with elemental concentations to characterize leaf litter and to estimate nutrient inputs and decomposition rates. C and N isotopes are being used to characterize watershed soils, soil biomass, and sedimentary rocks to constrain carbon fluxes to the rivers and the atmosphere. We are analyzing variations of C, O, and N stable isotopes of CO2, N2O and CH4 greenhouse gases in different temperature, precipitation, and hydrological regimes to connect climate change with biogeochemical fluxes between the watershed and the atmosphere.

Mass Balance of Multiyear Sea Ice in the Southern Beaufort Sea

DTIC Science & Technology

2015-09-30

1) Determination of the net growth and melt of multiyear (MY) sea ice during its transit through the southern Beaufort Sea 2) Identification of...which we refer to as the FGIV dataset. Analysis of melt processes from ice core and IMB data (Eicken) Through stratigraphic analysis of sea ice...samples that are brought back to shore were melted and used to determine profiles of salinity and stable isotope ratios. These data allow us to identify

Monitoring of the aerobe biodegradation of chlorinated organic solvents by stable isotope analysis

NASA Astrophysics Data System (ADS)

Horváth, Anikó; Futó, István; Palcsu, László

2014-05-01

Our chemical-biological basic research aims to eliminate chlorinated environmental contaminants from aquifers around industrial areas in the frame of research program supported by the European Social Fund (TÁMOP-4.2.2.A-11/1/KONV-2012-0043). The most careful and simplest way includes the in situ biodegradation with the help of cultured and compound specific strains. Numerous members of Pseudomonas bacteria are famous about function of bioremediation. They can metabolism the environmental hazardous chemicals like gas oils, dyes, and organic solvents. Our research based on the Pseudomonas putida F1 strain, because its ability to degrade halogenated hydrocarbons such as trichloroethylene. Several methods were investigated to estimate the rate of biodegradation, such as the measurement of the concentration of the pollutant along the contamination pathway, the microcosm's studies or the compound specific stable isotope analysis. In this area in the Transcarpathian basin we are pioneers in the stable isotope monitoring of biodegradation. The main goal is to find stable isotope fractionation factors by stable isotope analysis, which can help us to estimate the rate and effectiveness of the biodegradation. The subsequent research period includes the investigation of the method, testing its feasibility and adaptation in the environment. Last but not least, the research gives an opportunity to identify the producer of the contaminant based on the stable isotope composition of the contaminant.

Melting point of high-purity germanium stable isotopes

NASA Astrophysics Data System (ADS)

Gavva, V. A.; Bulanov, A. D.; Kut'in, A. M.; Plekhovich, A. D.; Churbanov, M. F.

2018-05-01

The melting point (Tm) of germanium stable isotopes 72Ge, 73Ge, 74Ge, 76Ge was determined by differential scanning calorimetry. With the increase in atomic mass of isotope the decrease in Tm is observed. The decrease was equal to 0.15 °C per the unit of atomic mass which qualitatively agrees with the value calculated by Lindemann formula accounting for the effect of "isotopic compression" of elementary cell.

Stable hydrogen isotope analysis of bat hair as evidence for seasonal molt and long-distance migration

USGS Publications Warehouse

Cryan, P.M.; Bogan, M.A.; Rye, R.O.; Landis, G.P.; Kester, C.L.

2004-01-01

Although hoary bats (Lasiurus cinereus) are presumed to be migratory and capable of long-distance dispersal, traditional marking techniques have failed to provide direct evidence of migratory movements by individuals. We measured the stable hydrogen isotope ratios of bat hair (δDh) and determined how these values relate to stable hydrogen isotope ratios of precipitation (δDp). Our results indicate that the major assumptions of stable isotope migration studies hold true for hoary bats and that the methodology provides a viable means of determining their migratory movements. We present evidence that a single annual molt occurs in L. cinereus prior to migration and that there is a strong relationship between δDh and δDp during the molt period. This presumably reflects the incorporation of local δDp into newly grown hair. Furthermore, we present evidence that individual hoary bats are capable of traveling distances in excess of 2,000 km and that hair is grown at a wide range of latitudes and elevations. Stable hydrogen isotope analysis offers a promising new tool for the study of bat migration.

Autotrophic fixation of geogenic CO2 by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

NASA Astrophysics Data System (ADS)

Nowak, M. E.; Beulig, F.; von Fischer, J.; Muhr, J.; Küsel, K.; Trumbore, S. E.

2015-12-01

To quantify the contribution of autotrophic microorganisms to organic matter (OM) formation in soils, we investigated natural CO2 vents (mofettes) situated in a wetland in northwest Bohemia (Czech Republic). Mofette soils had higher soil organic matter (SOM) concentrations than reference soils due to restricted decomposition under high CO2 levels. We used radiocarbon (Δ14C) and stable carbon (δ13C) isotope ratios to characterize SOM and its sources in two mofettes and compared it with respective reference soils, which were not influenced by geogenic CO2. The geogenic CO2 emitted at these sites is free of radiocarbon and enriched in 13C compared to atmospheric CO2. Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in 13C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0-10 cm layer of these soils was derived from microbially assimilated CO2. Isotope values of bulk SOM were shifted towards more positive δ13C and more negative Δ14C values in mofettes compared to reference soils, suggesting that geogenic CO2 emitted from the soil atmosphere is incorporated into SOM. To distinguish whether geogenic CO2 was fixed by plants or by CO2 assimilating microorganisms, we first used the proportional differences in radiocarbon and δ13C values to indicate the magnitude of discrimination of the stable isotopes in living plants. Deviation from this relationship was taken to indicate the presence of microbial CO2 fixation, as microbial discrimination should differ from that of plants. 13CO2-labelling experiments confirmed high activity of CO2 assimilating microbes in the top 10 cm, where δ13C values of SOM were shifted up to 2 ‰ towards more negative values. Uptake rates of microbial CO2 fixation ranged up to 1.59 ± 0.16 μg gdw-1 d-1. We inferred that the negative δ13C shift was caused by the activity of autotrophic microorganisms using the Calvin-Benson-Bassham (CBB) cycle, as indicated from quantification of cbbL/cbbM marker genes encoding for RubisCO by quantitative polymerase chain reaction (qPCR) and by acetogenic and methanogenic microorganisms, shown present in the mofettes by previous studies. Combined Δ14C and δ13C isotope mass balances indicated that microbially derived carbon accounted for 8-27 % of bulk SOM in this soil layer. The findings imply that autotrophic microorganisms can recycle significant amounts of carbon in wetland soils and might contribute to observed radiocarbon reservoir effects influencing Δ14C signatures in peat deposits.

Autotrophic fixation of geogenic CO2 by microorganisms contributes to soil organic matter formation and alters isotope signatures in a wetland mofette

NASA Astrophysics Data System (ADS)

Nowak, M. E.; Beulig, F.; von Fischer, J.; Muhr, J.; Küsel, K.; Trumbore, S. E.

2015-09-01

To quantify the contribution of autotrophic microorganisms to organic matter formation (OM) in soils, we investigated natural CO2 vents (mofettes) situated in a wetland in NW Bohemia (Czech Republic). Mofette soils had higher SOM concentrations than reference soils due to restricted decomposition under high CO2 levels. We used radiocarbon (Δ14C) and stable carbon isotope ratios (δ13C) to characterize SOM and its sources in two moffetes and compared it with respective reference soils, which were not influenced by geogenic CO2. The geogenic CO2 emitted at these sites is free of radiocarbon and enriched in δ13C compared to atmospheric CO2. Together, these isotopic signals allow us to distinguish C fixed by plants from C fixed by autotrophic microorganisms using their differences in δ13C discrimination. We can then estimate that up to 27 % of soil organic matter in the 0-10 cm layer of these soils was derived from microbially assimilated CO2. Isotope values of bulk SOM were shifted towards more positive δ13C and more negative Δ14C values in mofettes compared to reference soils, suggesting that geogenic CO2 emitted from the soil atmosphere is incorporated into SOM. To distinguish whether geogenic CO2 was fixed by plants or by CO2 assimilating microorganisms, we first used the proportional differences in radiocarbon and δ13C values to indicate the magnitude of discrimination of the stable isotopes in living plants. Deviation from this relationship was taken to indicate the presence of microbial CO2 fixation, as microbial discrimination should differ from that of plants. 13CO2-labelling experiments confirmed high activity of CO2 assimilating microbes in the top 10 cm, where δ13C values of SOM were shifted up to 2 ‰ towards more negative values. Uptake rates of microbial CO2 fixation ranged up to 1.59 ± 0.16 μg gdw-1 d-1. We inferred that the negative δ13C shift was caused by the activity of chemo-lithoautotrophic microorganisms, as indicated from quantification of cbbL/cbbM marker genes encoding for RubisCO by quantitative polymerase chain reaction (qPCR) and by acetogenic and methanogenic microorganisms, shown present in the moffettes by previous studies. Combined Δ14C and δ13C isotope mass balances indicated that microbially derived carbon accounted for 8 to 27 % of bulk SOM in this soil layer. The findings imply that autotrophic organisms can recycle significant amounts of carbon in wetland soils and might contribute to observed reservoir effects influencing radiocarbon signatures in peat deposits.

Faunal and stable isotopic analyses of benthic foraminifera from the Southeast Seep on Kimki Ridge offshore southern California, USA

USGS Publications Warehouse

McGann, Mary; Conrad, James E.

2018-01-01

We investigated the benthic foraminiferal faunal and stable carbon and oxygen isotopic composition of a 15-cm push core (NA075-092b) obtained on a Telepresence-Enabled cruise to the Southeast Seep on Kimki Ridge offshore southern California. The seep core was taken at a depth of 973 m in the vicinity of a Beggiatoa bacterial mat and vesicomyid clams (Calyptogena) and compared to previously published data of living assemblages from ~ 714 m, four reference cores obtained at ~ 1030 m, and another one at 739 m. All of the reference sites are also from the Inner Continental Borderland but with no evidence of methane seepage.No endemic species were found at the seep site and most of the taxa recovered there have been reported previously from other seep or low oxygen environments. Q- and R-mode cluster analyses clearly illustrated differences in the faunal assemblages of the seep and non-seep sites. The living assemblage at Southeast Seep was characterized by abundant Takayanagia delicata, Cassidulina translucens, and Spiroplectammina biformis, whereas the non-seep San Pedro Basin reference assemblage was comprised primarily of Chilostomella oolina and Globobulimina pacifica. Density and species richness were lower at the seep site compared to the non-seep site, reflecting the harsher living conditions there. The dead assemblage at the seep site was dominated by Gyroidina turgida compared to Cassidulina translucens at the ~ 1030 m non-seep site and Cassidulina translucens, Pseudoparrella pacifica, and Takayanagia delicata at the 739 m non-seep site. Density was three times lower at Southeast Seep than at the non-seep sites of comparable water depth but species richness was ~ 30% higher. Stable carbon isotopic values were considerably depleted in the seep samples compared to the non-seep samples, with a progression from lightest to heaviest average δ13C values evident at the seep site reflecting microhabitat preference and vital effect: the deep infaunal species of Globobulimina, the shallow infaunal species Uvigerina peregrina, the epifaunal species Cibicidoides wuellerstorfi, and the shallow infaunal but aragonite-shelled species Hoeglundina elegans. The δ13C values downcore among each benthic species indicates ongoing fluid seepage through at least the last 3800 cal yr B.P. at Southeast Seep. Besides the continual local seepage, evidence from δ13C values of planktic foraminifera in the seep core suggest two pulses of methane (at 3000 and 3700 cal yr B.P.) were released that were large enough to influence much of the water column. Paired benthic and planktic foraminiferal stable oxygen isotope records provide evidence that there were no paleoenvironmental changes such as increased bottom-water temperature or changes in oxygen isotopic composition of bottom and pore waters during this 3800-year record to induce the methane releases. Instead, Southeast Seep appears to be the result of local faulting providing pathways for fluid to flow to the seafloor at a fault stepover or transpressional bend in the regional strike-slip system.

USE OF GC-MS/COMBUSTION/IRMS TO IDENTIFY AND DETERMINE THE STABLE CARBON ISOTOPIC RATIO OF INDIVIDUAL LIPIDS

EPA Science Inventory

A system that couples a gas chromatograph (GC) via a split to a quadrapole mass spectrometer (MS) and, through a combustion interface, to an isotope ratio mass spectrometer (IRMS) allows the simultaneous detection of electron impact mass spectra and stable carbon isotope ratio an...

A Guide for Assessing Biodegradation and Source Identification of Organic Groundwater Contaminants Using Compound Specific Isotope Analysis (CSIA)

EPA Science Inventory

When organic contaminants are degraded in the environment, the ratio of stable isotopes will often change, and the extent of degradation can be recognized and predicted from the change in the ratio of stable isotopes. Recent advances in analytical chemistry make it possible to p...

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)

Spatial and Temporal Trends in Stable Carbon and Oxygen Isotope Ratios of Juvenile Winter Flounder

EPA Science Inventory

Isotopic ratios of fish otoliths have been used in numerous studies as natural tags or markers to aid the study of connectivity among fish populations. We investigated the use of spatial and temporal changes in the stable carbon and oxygen isotope ratios of otoliths to different...

Discrimination of ginseng cultivation regions using light stable isotope analysis.

PubMed

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

2015-10-01

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

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.

Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes

USGS Publications Warehouse

Blazer, V.S.; Hoffman, J.; Walsh, H.L.; Braham, R.P.; Hahn, C.; Collins, P.; Jorgenson, Z.; Ledder, T.

2014-01-01

In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River area of concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abnormalities were documented and preserved for microscopic analyses, as were five to eight representative pieces of liver tissue. A piece of dorsal muscle was preserved for stable isotope analyses and otoliths removed for age determination. The incidence of raised skin lesions (mucoid plaques) was high (31 %), however, microscopically only 4.5 % of the white suckers had neoplasia (papillomas). The remaining lesions were epidermal hyperplasia. Superior Bay had the lowest percentage of skin/lip lesions (10 %), while St. Louis Bay had the highest (44 %). St. Louis Bay also had the highest incidence of skin neoplasms (12 %). No hepatocellular neoplasms were documented, however bile duct tumors were observed in 4.5 % of the suckers. Foci of cellular alteration were observed in fish from all sites except the upper AOC. Stable isotope data indicated that most of the suckers relied on the St. Louis River AOC for the majority (>75 %) of their diet, indicating they were resident within the AOC and not in Lake Superior. The amount of diet obtained from the upper estuary was a significant predictor of skin lesion incidence. Hence, habitat use within the AOC appears to be an important risk factor for skin and possibly, liver lesions.

Analyses of stomach contents and stable isotopes reveal food sources of estuarine detritivorous fish in tropical/subtropical Taiwan

NASA Astrophysics Data System (ADS)

Lin, Hsing-Juh; Kao, Wen-Yuan; Wang, Ya-Ting

2007-07-01

Detritivorous fish generally refers to fish that primarily ingest unidentified organic detritus. We analyzed stomach contents in combination with stable isotopes to trace and compare the food sources of the large-scale mullet Liza macrolepis and other detritivorous fish species in subtropical mangrove creeks and a tropical lagoon in Taiwan. The volume of organic detritus always contributed >50% of the stomach content of L. macrolepis in the two habitats. However, consumed items were distinct between the two habitats and corresponded to the types in which they reside. The consumed items in the lagoon were more diverse than those observed in the mangroves. In the mangroves, the diet composition of L. macrolepis was primarily determined by season, not by body size. In the lagoon, there were no clear seasonal or size-dependent grouping patterns for the diet composition. There were significant seasonal and spatial variations in δ13C and δ15N values of potential food sources and L. macrolepis. However, neither δ13C nor δ15N values of L. macrolepis were correlated with fish body size. Joint analyses of stomach contents and stable isotopes indicated that benthic microalgae on sediments were the most important assimilated food in both seasons for the dominant detritivorous fish in the mangroves, whereas a greater reliance on microalgal and macroalgal periphyton on oyster-culture pens was observed in the lagoon. Mangrove and marsh plants and phytoplankton, which are mostly locally produced within each habitat, were of minor importance in the assimilated food.

Health of white sucker within the St. Louis River area of concern associated with habitat usage as assessed using stable isotopes.

PubMed

Blazer, V S; Hoffman, J; Walsh, H L; Braham, R P; Hahn, C; Collins, P; Jorgenson, Z; Ledder, T

2014-03-01

In Spring 2011, 200 adult white sucker were collected in four areas of the St. Louis River area of concern (AOC), located in Minnesota and Wisconsin, USA. The areas included the upper AOC as a reference area, the upper estuary, St. Louis Bay and Superior Bay. Grossly visible abnormalities were documented and preserved for microscopic analyses, as were five to eight representative pieces of liver tissue. A piece of dorsal muscle was preserved for stable isotope analyses and otoliths removed for age determination. The incidence of raised skin lesions (mucoid plaques) was high (31 %), however, microscopically only 4.5 % of the white suckers had neoplasia (papillomas). The remaining lesions were epidermal hyperplasia. Superior Bay had the lowest percentage of skin/lip lesions (10 %), while St. Louis Bay had the highest (44 %). St. Louis Bay also had the highest incidence of skin neoplasms (12 %). No hepatocellular neoplasms were documented, however bile duct tumors were observed in 4.5 % of the suckers. Foci of cellular alteration were observed in fish from all sites except the upper AOC. Stable isotope data indicated that most of the suckers relied on the St. Louis River AOC for the majority (>75 %) of their diet, indicating they were resident within the AOC and not in Lake Superior. The amount of diet obtained from the upper estuary was a significant predictor of skin lesion incidence. Hence, habitat use within the AOC appears to be an important risk factor for skin and possibly, liver lesions.

Constraining recent lead pollution sources in the North Pacific using ice core stable lead isotopes

NASA Astrophysics Data System (ADS)

Kreutz, K. J.; Osterberg, E. C.; Gross, B.; Handley, M.; Wake, C. P.; Yalcin, K.

2009-12-01

Trends and sources of lead aerosol pollution in the North Pacific boundary layer from 1970-2001 are investigated using a high-resolution ice core record recovered from Eclipse Icefield (3017 masl; St. Elias Mountains, Canada). Average Pb concentrations in the ice core are enriched 31.8 times above crustal values based on ratios with five crustal reference elements (La, Ce, Pr, Al and Ti), indicating that >90% of the Pb deposited is anthropogenic. Isotopic analyses (208Pb/207Pb and 206Pb/207Pb) confirm that the Pb deposited at Eclipse Icefield is predominantly anthropogenic. Annually averaged Pb concentrations range from 25.6 ng/l to 96.7 ng/l (67.6 ng/l mean) and show no long term trend for the 1970-2001 period, contrary to other ice core records from the North Atlantic and the North Pacific. The stable Pb isotope ratio (208Pb/207Pb and 206Pb/207Pb) field indicates that recent Eclipse Icefield Pb pollution represents a variable mixture of North American, Central Eurasian and Asian (Chinese and Japanese) emissions transported across the Pacific basin, with Chinese coal combustion likely being the primary source. Increasing 208Pb/207Pb and 206Pb/207Pb ratios from the 1970’s through 2001 reflect the progressive East Asian industrialization concurrent with a decrease in Eurasian Pb emissions. We compare Pb isotope results from the Eclipse Icefield to data recently acquired from Denali National Park, where snowpit samples were collected from the Kahiltna Pass region (3048 masl). Pb isotope data from both sites are used to evaluate the relative importance of Asian emissions at similar altitudes yet different latitudes.

The synthesis of a tritium, carbon-14, and stable isotope-labeled cathepsin C inhibitors.

PubMed

Allen, Paul; Bragg, Ryan A; Caffrey, Moya; Ericsson, Cecilia; Hickey, Michael J; Kingston, Lee P; Elmore, Charles S

2017-02-01

As part of a medicinal chemistry program aimed at developing a highly potent and selective cathepsin C inhibitor, tritium, carbon-14, and stable isotope-labeled materials were required. The synthesis of tritium-labeled methanesulfonate 5 was achieved via catalytic tritiolysis of a chloro precursor, albeit at a low radiochemical purity of 67%. Tritium-labeled AZD5248 was prepared via a 3-stage synthesis, utilizing amide-directed hydrogen isotope exchange. Carbon-14 and stable isotope-labeled AZD5248 were successfully prepared through modifications of the medicinal chemistry synthetic route, enabling the use of available labeled intermediates. Copyright © 2016 John Wiley & Sons, Ltd.

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

NASA Astrophysics Data System (ADS)

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

2010-05-01

Stable isotope analysis of biogenic tissues such as tooth enamel and bone mineral has become a well recognized and increasingly important method for determining provenance of human remains, and has been used successfully in bioarchaeological studies as well as forensic investigations (Lee-Thorp, 2008; Meier-Augenstein and Fraser, 2008). Particularly, 18O and 2H stable isotopes are well established proxies as environmental indicators of climate (temperature) and source water and are therefore considered as indicators of geographic life trajectories of animals and humans (Hobson et al., 2004; Schwarcz and Walker, 2006). While methodology for 2H analysis of human hair, fingernails, and bone collagen is currently used to determine geographic origin and identify possible migration patterns, studies involving the analysis of 2H in tooth enamel appear to be nonexistent in the scientific literature. The apparent lack of research in this area is believed to have two main reasons. (1) Compared to the mineral calcium hydroxylapatite Ca10(PO4)6(OH)2, in tooth enamel forming bio-apatite carbonate ions replace some of the hydroxyl ions at a rate of one CO32 replacing two OH, yet published figures for the degree of substitution vary (Wopenka and Pasteris, 2005). (2) Most probably due to the aforementioned no published protocols exist for sample preparation and analytical method to obtain δ2H-values from the hydroxyl fraction of tooth enamel. This dilemma has been addressed through a pilot study to establish feasibility of 2H stable isotope analysis of ground tooth enamel by continuous-flow isotope ratio mass spectrometry (IRMS) coupled on-line to a high-temperature conversion elemental analyzer (TC/EA). An array of archaeological and modern teeth has been analyzed under different experimental conditions, and results from this pilot study are being presented. References: Lee-Thorp, J.A. (2008) Archaeometry, 50, 925-950 Meier-Augenstein, W. and Fraser, I. (2008) Science & Justice, 48, 153-159 Hobson, K.A., Bowen, G.J., Wassenaar, L.I., Ferrand, Y. and Lormee, H. (2004) Oecologia, 141, 477-488 Schwarcz, H.P. and Walker, P.L. (2006) American Journal of Physical Anthropology, 129, 160 Wopenka, B. and Pasteris, J.D. (2005) Materials Science and Engineering C, 25, 131-143

Laboratory investigations of stable carbon and oxygen isotope ratio data enhance monitoring of CO2 underground

NASA Astrophysics Data System (ADS)

Barth, Johannes A. C.; Myrttinen, Anssi; Becker, Veith; Nowak, Martin; Mayer, Bernhard

2014-05-01

Stable carbon and oxygen isotope data play an important role in monitoring CO2 in the subsurface, for instance during carbon capture and storage (CCS). This includes monitoring of supercritical and gaseous CO2 movement and reactions under reservoir conditions and detection of potential CO2 leakage scenarios. However, in many cases isotope data from field campaigns are either limited due to complex sample retrieval or require verification under controlled boundary conditions. Moreover, experimentally verified isotope fractionation factors are also accurately known only for temperatures and pressures lower than commonly found in CO2 reservoirs (Myrttinen et al., 2012). For this reason, several experimental series were conducted in order to investigate effects of elevated pressures, temperatures and salinities on stable carbon and oxygen isotope changes of CO2 and water. These tests were conducted with a heateable pressure device and with glass or metal gas containers in which CO2 reacted with fluids for time periods of hours to several weeks. The obtained results revealed systematic differences in 13C/12C-distributions between CO2 and the most important dissolved inorganic carbon (DIC) species under reservoir conditions (CO2(aq), H2CO3 and HCO3-). Since direct measurements of the pH, even immediately after sampling, were unreliable due to rapid CO2 de-gassing, one of the key results of this work is that carbon isotope fractionation data between DIC and CO2 may serve to reconstruct in situ pH values. pH values reconstructed with this approach ranged between 5.5 and 7.4 for experiments with 60 bars and up to 120 °C and were on average 1.4 pH units lower than those measured with standard pH electrodes directly after sampling. In addition, pressure and temperature experiments with H2O and CO2 revealed that differences between the oxygen isotope ratios of both phases depended on temperature, water-gas ratios as well as salt contents of the solutions involved. Such systematic knowledge of the extent of oxygen isotope fractionation between H2O and CO2 can help to reconstruct equilibration times, fluid-CO2 ratios as well as temperature and salinity conditions. Isotope results from systematic laboratory studies and the information they provide for assessing in situ reservoir conditions can be transferred to field applications concerning integrity of CO2 reservoirs. They can also apply to natural systems and other industrial uses that involve monitoring of gases in the subsurface under similar pressure and temperature conditions. Reference: Myrttinen, A., Becker, V., Barth, J.A.C., 2012. A review of methods used for equilibrium isotope fractionation investigations between dissolved inorganic carbon and CO2. Earth-Science Reviews, 115(3): 192-199.

Variation in the terrestrial isotopic composition and atomic weight of argon

USGS Publications Warehouse

Böhlke, John Karl

2014-01-01

The isotopic composition and atomic weight of argon (Ar) are variable in terrestrial materials. Those variations are a source of uncertainty in the assignment of standard properties for Ar, but they provide useful information in many areas of science. Variations in the stable isotopic composition and atomic weight of Ar are caused by several different processes, including (1) isotope production from other elements by radioactive decay (radiogenic isotopes) or other nuclear transformations (e.g., nucleogenic isotopes), and (2) isotopic fractionation by physical-chemical processes such as diffusion or phase equilibria. Physical-chemical processes cause correlated mass-dependent variations in the Ar isotope-amount ratios (40Ar/36Ar, 38Ar/36Ar), whereas nuclear transformation processes cause non-mass-dependent variations. While atmospheric Ar can serve as an abundant and homogeneous isotopic reference, deviations from the atmospheric isotopic ratios in other Ar occurrences limit the precision with which a standard atomic weight can be given for Ar. Published data indicate variation of Ar atomic weights in normal terrestrial materials between about 39.7931 and 39.9624. The upper bound of this interval is given by the atomic mass of 40Ar, as some samples contain almost pure radiogenic 40Ar. The lower bound is derived from analyses of pitchblende (uranium mineral) containing large amounts of nucleogenic 36Ar and 38Ar. Within this interval, measurements of different isotope ratios (40Ar/36Ar or 38Ar/36Ar) at various levels of precision are widely used for studies in geochronology, water–rock interaction, atmospheric evolution, and other fields.

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.

Reactive transport modeling of stable carbon isotope fractionation in a multi-phase multi-component system during carbon sequestration

DOE PAGES

Zhang, Shuo; DePaolo, Donald J.; Zheng, Liange; ...

2014-12-31

Carbon stable isotopes can be used in characterization and monitoring of CO 2 sequestration sites to track the migration of the CO 2 plume and identify leakage sources, and to evaluate the chemical reactions that take place in the CO 2-water-rock system. However, there are few tools available to incorporate stable isotope information into flow and transport codes used for CO 2 sequestration problems. We present a numerical tool for modeling the transport of stable carbon isotopes in multiphase reactive systems relevant to geologic carbon sequestration. The code is an extension of the reactive transport code TOUGHREACT. The transport modulemore » of TOUGHREACT was modified to include separate isotopic species of CO 2 gas and dissolved inorganic carbon (CO 2, CO 3 2-, HCO 3 -,…). Any process of transport or reaction influencing a given carbon species also influences its isotopic ratio. Isotopic fractionation is thus fully integrated within the dynamic system. The chemical module and database have been expanded to include isotopic exchange and fractionation between the carbon species in both gas and aqueous phases. The performance of the code is verified by modeling ideal systems and comparing with theoretical results. Efforts are also made to fit field data from the Pembina CO 2 injection project in Canada. We show that the exchange of carbon isotopes between dissolved and gaseous carbon species combined with fluid flow and transport, produce isotopic effects that are significantly different from simple two-component mixing. These effects are important for understanding the isotopic variations observed in field demonstrations.« less

CCQM-K140: carbon stable isotope ratio delta values in honey

NASA Astrophysics Data System (ADS)

Dunn, P. J. H.; Goenaga-Infante, H.; Goren, A. C.; Şimşek, A.; Bilsel, M.; Ogrinc, N.; Armishaw, P.; Hai, L.

2017-01-01

As there can be small but measureable differences in isotope ratios between different sources of the same element/compound/material, isotope ratio measurements are applied in a number of different fields including archaeology, environmental science, geochemistry, forensic science and ecology. Isotope ratios for the light elements (H, C, N, O and S) are typically reported as δ-values which are isotope ratios expressed relative to an internationally agreed standard (this standard is the zero-point on the scale), although absolute isotope ratios which are traceable to the SI have also been reported. The IAWG has been granted a traceability exception for the use of arbitrary delta scales until SI traceability can be established at the required level of uncertainty but this goal is some years away. While the CCQM IAWG has previously organised several pilot studies on isotope ratio determination (CCQM-P75: Stable isotope delta values in methionine, 2006; CCQM-P105: Sr isotope ratios in wine, 2008; CCQM-K98: Pb isotope ratios in bronze with additional delta values in CCQM-P134, 2011), it has been a number of years since delta values of light elements have been considered and there has been no key comparison (KC). Therefore, the IAWG has included the need for a KC (CCQM-K140) based on an arbitrary delta scale in its program to support ongoing requirements to demonstrate core capabilities as well as specific claims of measurement capability (CMCs) in this area. The performance of all five of the CCQM-K140 participants was very good, illustrating their ability to obtain accurate results for carbon isotope ratios, within the calibration range afforded by internationally agreed reference materials (δ13CVPDB-LSVEC between -47.32 % and +535.3 %) with measurement uncertainties of between 0.08 and 0.28 %. This was despite the fact that no two participants used exactly the same approach in terms of instrumentation or data treatment. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Baseline shifts in coral skeletal oxygen isotopic composition: a signature of symbiont shuffling?

NASA Astrophysics Data System (ADS)

Carilli, J. E.; Charles, C. D.; Garren, M.; McField, M.; Norris, R. D.

2013-06-01

Decades-long records of the stable isotopic composition of coral skeletal cores were analyzed from four sites on the Mesoamerican Reef. Two of the sites exhibited baseline shifts in oxygen isotopic composition after known coral bleaching events. Changes in pH at the calcification site caused by a change in the associated symbiont community are invoked to explain the observed shift in the isotopic composition. To test the hypothesis that changes in symbiont clade could affect skeletal chemistry, additional coral samples were collected from Belize for paired Symbiodinium identification and skeletal stable isotopic analysis. We found some evidence that skeletal stable isotopic composition may be affected by symbiont clade and suggest this is an important topic for future investigation. If different Symbiodinium clades leave consistent signatures in skeletal geochemical composition, the signature will provide a method to quantify past symbiont shuffling events, important for understanding how corals are likely to respond to climate change.

Effects of euthanasia method on stable-carbon and stable-nitrogen isotope analysis for an ectothermic vertebrate.

PubMed

Atwood, Meredith A

2013-04-30

Stable isotope analysis is a critical tool for understanding ecological food webs; however, results can be sensitive to sample preparation methods. To limit the possibility of sample contamination, freezing is commonly used to euthanize invertebrates and preserve non-lethal samples from vertebrates. For destructive sampling of vertebrates, more humane euthanasia methods are preferred to freezing and it is essential to evaluate how these euthanasia methods affect stable isotope results. Stable isotope ratios and elemental composition of carbon and nitrogen were used to evaluate whether the euthanasia method compromised the integrity of the sample for analysis. Specifically, the stable isotope and C:N ratios were compared for larval wood frogs (Rana sylvatica  =  Lithobates sylvaticus), an ectothermic vertebrate, that had been euthanized by freezing with four different humane euthanasia methods: CO2, benzocaine, MS-222 (tricaine methanesulfonate), and 70% ethanol. The euthanasia method was not related to the δ(13)C or δ(15)N values and the comparisons revealed no differences between freezing and any of the other treatments. However, there were slight (non-significant) differences in the isotope ratios of benzocaine and CO2 when each was compared with freezing. The elemental composition was altered by the euthanasia method employed. The percentage nitrogen was higher in CO2 treatments than in freezing, and similar (non-significant) trends were seen for ethanol treatments relative to freezing. The resulting C:N ratios were higher for benzocaine treatments than for both CO2 and ethanol. Similar (non-significant) trends suggested that the C:N ratios were also higher for animals euthanized by freezing than for both CO2 and ethanol euthanasia methods. The euthanasia method had a larger effect on elemental composition than stable isotope ratios. The percentage nitrogen and the subsequent C:N ratios were most affected by the CO2 and ethanol euthanasia methods, whereas non-significant trends suggested that benzocaine and CO2 altered the stable isotope ratios. It appears that the use of MS-222 and freezing with dry ice are the most appropriate euthanasia methods for ectothermic vertebrates. Copyright © 2013 John Wiley & Sons, Ltd.

Lithium and carbon isotopes in river catchment: combined tracers to constrain chemical weathering processes

NASA Astrophysics Data System (ADS)

Rad, S.; Rive, K.; Assayag, N.; Dictor, M.; Garcin, M.

2012-12-01

Water-rock interactions produced in river catchment are accompanied by fractionation or changes in stable isotopes such as H, Li, C and O during chemical weathering processes. Li is a fluid-mobile element that tends to preferentially partition into the fluid phase during water-rock interaction. The relative mass difference between the two isotopes is considerable, generating large mass dependent fractionation during chemical weathering processes. The CO2 dissolves into the water providing the main acid that attack the rock during chemical weathering. Carbon stable isotopes and concentration of Dissolved Inorganic Carbon (DIC) in the river catchment can be used to determine the origin and consumption rates of CO2. In the present work, stable isotopes were analyzed in Allier River, one of the major river basins of France. The lithology is dominated by granite rocks within current upstream, while it is mainly basaltic and Oligocene sediments in the downstream with hydrothermal manifestations. We propose a new isotopic approach by combining δ7Li and δ13CDIC analyses in river catchment waters. A first method has been applied to volcanic tropical environments with Li concentrations correlated to δ13CDIC (Rad et al., 2011). Here, we have completed this approach by lithium isotopes. Water samples were collected during several field trips. Our results show a large variation in Li isotopes and C isotopes within the catchment from 3.3 ‰ to 30.3 ‰ and from -17.9‰ to -3.5‰, respectively. Chemical weathering rates linearly increase from upstream to downstream over 400km distance, whereas Li isotope signatures decrease and global C signature increases. This is due to low water-rock interaction dominated in upstream, whereas the downstream is punctually impacted by hydrothermalism. From Li and C isotopes, our results show 4 groups reflecting different chemical weathering processes: the first group with high fractionation of Li and C, for Li, the heavy lithium partitioned into surface waters, leaving lighter lithium behind in the weathered products, the signature of C is mainly due to organic matter or partially due to biochemical interaction with assimilation of CO2 by microorganism. The second group involves atmospheric equilibrium with CO2 degassing with organic origin or "cold" CO2 degassing with important fraction of Li. The third group present high fractionation of C, reflecting presence of superficial C with organic origin, with low fractionation of Li underling the hydrothermalism impact. Finally a fourth group with low fractionation mainly due to high temperature water-rock interaction. Therefore, the combination of the two tracers, Li and C isotopes, offers a powerful tool to discriminate chemical weathering processes from sources of alteration during water-rock interactions under multi-lithology terrains. Reference: Rad, S., Rivé, K., Allègre, C.J., 2011. Weathering regime associated with subsurface circulation on volcanic islands. Aquat. Geochem. 17, 3, 221-241.

New Carbonate Standard Reference Materials for Boron Isotope Geochemistry

NASA Astrophysics Data System (ADS)

Stewart, J.; Christopher, S. J.; Day, R. D.

2015-12-01

The isotopic composition of boron (δ11B) in marine carbonates is well established as a proxy for past ocean pH. Yet, before palaeoceanographic interpretation can be made, rigorous assessment of analytical uncertainty of δ11B data is required; particularly in light of recent interlaboratory comparison studies that reported significant measurement disagreement between laboratories [1]. Well characterised boron standard reference materials (SRMs) in a carbonate matrix are needed to assess the accuracy and precision of carbonate δ11B measurements throughout the entire procedural chemistry; from sample cleaning, to ionic separation of boron from the carbonate matrix, and final δ11B measurement by multi-collector inductively coupled plasma mass spectrometry. To date only two carbonate reference materials exist that have been value-assigned by the boron isotope measurement community [2]; JCp-1 (porites coral) and JCt-1 (Giant Clam) [3]. The National Institute of Standards and Technology (NIST) will supplement these existing standards with new solution based inorganic carbonate boron SRMs that replicate typical foraminiferal and coral B/Ca ratios and δ11B values. These new SRMs will not only ensure quality control of full procedural chemistry between laboratories, but have the added benefits of being both in abundant supply and free from any restrictions associated with shipment of biogenic samples derived from protected species. Here we present in-house δ11B measurements of these new boron carbonate SRM solutions. These preliminary data will feed into an interlaboratory comparison study to establish certified values for these new NIST SRMs. 1. Foster, G.L., et al., Chemical Geology, 2013. 358(0): p. 1-14. 2. Gutjahr, M., et al., Boron Isotope Intercomparison Project (BIIP): Development of a new carbonate standard for stable isotopic analyses. Geophysical Research Abstracts, EGU General Assembly 2014, 2014. 16(EGU2014-5028-1). 3. Inoue, M., et al., Geostandards and Geoanalytical Research, 2004. 28(3): p. 411-416.

Detecting intraannual dietary variability in wild mountain gorillas by stable isotope analysis of feces

PubMed Central

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

2012-01-01

We use stable isotope ratios in feces of wild mountain gorillas (Gorilla beringei) to test the hypothesis that diet shifts within a single year, as measured by dry mass intake, can be recovered. Isotopic separation of staple foods indicates that intraannual changes in the isotopic composition of feces reflect shifts in diet. Fruits are isotopically distinct compared with other staple foods, and peaks in fecal δ13C values are interpreted as periods of increased fruit feeding. Bayesian mixing model results demonstrate that, although the timing of these diet shifts match observational data, the modeled increase in proportional fruit feeding does not capture the full shift. Variation in the isotopic and nutritional composition of gorilla foods is largely independent, highlighting the difficulty for estimating nutritional intake with stable isotopes. Our results demonstrate the potential value of fecal sampling for quantifying short-term, intraindividual dietary variability in primates and other animals with high temporal resolution even when the diet is composed of C3 plants. PMID:23236160

Dietary change and stable isotopes: a model of growth and dormancy in cave bears.

PubMed Central

Lidén, K; Angerbjörn, A

1999-01-01

In order to discuss dietary change over time by the use of stable isotopes, it is necessary to sort out the underlying processes in isotopic variation. Together with the dietary signal other processes have been investigated, namely metabolic processes, collagen turnover and physical growth. However, growth and collagen turnover time have so far been neglected in dietary reconstruction based on stable isotopes. An earlier study suggested that cave bears (Ursus spelaeus) probably gave birth to cubs during dormancy. We provide an estimate of the effect on stable isotopes of growth and metabolism and discuss collagen turnover in a population of cave bears. Based on a quantitative model, we hypothesized that bear cubs lactated their mothers during their first and second winters, but were fed solid food together with lactation during their first summer. This demonstrates the need to include physical growth, metabolism and collagen turnover in dietary reconstruction. Whereas the effects of diet and metabolism are due to fractionation, growth and collagen turnover are dilution processes. PMID:10518325

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.

The plasma separation process as a pre-cursor for large scale radioisotope production

NASA Astrophysics Data System (ADS)

Stevenson, Nigel R.

2001-07-01

Radioisotope production generally employs either accelerators or reactors to convert stable (usually enriched) isotopes into the desired product species. Radioisotopes have applications in industry, environmental sciences, and most significantly in medicine. The production of many potentially useful radioisotopes is significantly hindered by the lack of availability or by the high cost of key enriched stable isotopes. To try and meet this demand, certain niche enrichment processes have been developed and commercialized. Calutrons, centrifuges, and laser separation processes are some of the devices and techniques being employed to produce large quantities of selective enriched stable isotopes. Nevertheless, the list of enriched stable isotopes in sufficient quantities remains rather limited and this continues to restrict the availability of many radioisotopes that otherwise could have a significant impact on society. The Plasma Separation Process is a newly available commercial technique for producing large quantities of a wide range of enriched isotopes and thereby holds promise of being able to open the door to producing new and exciting applications of radioisotopes in the future.

Source indicators of humic substances and proto-kerogen - Stable isotope ratios, elemental compositions and electron spin resonance spectra

NASA Technical Reports Server (NTRS)

Stuermer, D. H.; Peters, K. E.; Kaplan, I. R.

1978-01-01

Stable isotope ratios of C, N and H, elemental compositions, and electron spin resonance (ESR) data of humic acids and proto-kerogens from twelve widely varying sampling locations are presented. Humic acids and proto-kerogens from algal sources are more aliphatic and higher in N than those from higher plant sources. Oxygen content appears to represent a measure of maturation, even in Recent sediments, and S content may reflect redox conditions in the environment of deposition. The ESR data indicate that the transformation of humic substances to proto-kerogens in Recent sediments is accompanied by an increase in aromatic character. A combination of stable carbon isotope ratio and H/C ratio may be a simple but reliable source indicator which allows differentiation of marine-derived from terrestrially-derived organic matter. The stable nitrogen isotope ratios are useful indicators of nitrogen nutrient source. Deuterium/hydrogen isotope ratios appear to reflect variations in meteoric waters and are not reliable source indicators.

Testing sequential extraction methods for the analysis of multiple stable isotope systems from a bone sample

NASA Astrophysics Data System (ADS)

Sahlstedt, Elina; Arppe, Laura

2017-04-01

Stable isotope composition of bones, analysed either from the mineral phase (hydroxyapatite) or from the organic phase (mainly collagen) carry important climatological and ecological information and are therefore widely used in paleontological and archaeological research. For the analysis of the stable isotope compositions, both of the phases, hydroxyapatite and collagen, have their more or less well established separation and analytical techniques. Recent development in IRMS and wet chemical extraction methods have facilitated the analysis of very small bone fractions (500 μg or less starting material) for PO43-O isotope composition. However, the uniqueness and (pre-) historical value of each archaeological and paleontological finding lead to preciously little material available for stable isotope analyses, encouraging further development of microanalytical methods for the use of stable isotope analyses. Here we present the first results in developing extraction methods for combining collagen C- and N-isotope analyses to PO43-O-isotope analyses from a single bone sample fraction. We tested sequential extraction starting with dilute acid demineralization and collection of both collagen and PO43-fractions, followed by further purification step by H2O2 (PO43-fraction). First results show that bone sample separates as small as 2 mg may be analysed for their δ15N, δ13C and δ18OPO4 values. The method may be incorporated in detailed investigation of sequentially developing skeletal material such as teeth, potentially allowing for the investigation of interannual variability in climatological/environmental signals or investigation of the early life history of an individual.

Soil Biogeochemical Properties and Erosion Source Prediction Model Summary for the Buffalo Bayou Watershed, Houston, Texas

NASA Astrophysics Data System (ADS)

Ahmed, I.

2015-12-01

We draw conclusions on the research output and findings from a 4-year multidisciplinary USDA-CBG collaborative program in sustainable integrated monitoring of soil organic carbon (SOC) loss prediction via erosion. The underlying method uses the state-of-the-art stable isotope science of sediment tracing under uncertain hydrologic influences. The research finds are rooted in the (i) application of Bayesian Markov Chain Monte Carlo statistical models to assess the relationship between rainfall-runoff and soil erosion in space and time, (ii) capture of the episodic nature of rainfall events and its role in the spatial distribution of SOC loss from water erosion, (iii) stable isotope composition guided fingerprinting (source and quantity) of eroded soil, and (iv) the creation of an integrated watershed scale statistical soil loss monitoring model driven by spatial and temporal correlation of flow and stable isotope composition. The research theme was successfully applied on the urbanized Buffalo Bayou Watershed in Houston, Texas. The application brought to light novel future research conceptual outlines which will also be discussed in this deliverable to the AGU meeting. These include but not limited to: regional rainfall cluster research, physics of muddy river-bank soil and suspended sediment interaction, and friction & mobility that together make up the plasticity of soil aggregates that control erosion processes and landscape changes in a riparian corridor. References: Ahmed, I., Karim, A., Boutton, T.W., and Strom, K.B. (2013a). "Monitoring Soil Organic Carbon Loss from Erosion Using Stable Isotopes." Proc., Soil Carbon Sequestration, International Conference, May 26-29, Reykjavik, Iceland. Ahmed, I, Bouttom, T.W., Strom, K. B., Karim, A., and Irvin-Smith, N. (2013b). "Soil carbon distribution and loss monitoring in the urbanized Buffalo Bayou watershed, Houston, Texas." Proc., 4th Annual All Investigators Meeting of the North American Carbon Program, February 4-7, Albuquerque, NM. Fox, J.F. and Papanicolaou, A.N. (2008). An un-mixing model to study watershed erosion processes. Advances in Water Resources, 31, 96-108.

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

PubMed

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

2014-06-01

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

Advances in primate stable isotope ecology-Achievements and future prospects.

PubMed

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

2016-10-01

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

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

PubMed

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

2012-10-01

Zinc stable isotope tracers (⁶⁷Zn and ⁷⁰Zn) were injected into rats at two different time points to investigate the feasibility of using tracers to study zinc kinetics at the microscale within distinct tissue features. Laser ablation coupled to multi-collector ICP-MS was used to analyse average isotope ratios in liver thin sections and to generate bio-images showing zinc isotope ratio distribution in brain thin sections. Average isotope ratios of all samples from treated animals were found to be statistically different (P < 0.05) from samples from untreated control animals. Furthermore, differing isotope ratios in physiological features of the brain, namely hippocampus, amygdala, cortex and hypothalamus, were identified. This indicates that these regions differ in their zinc metabolism kinetics. While cortex and hypothalamus contain more tracer two days after injection than 14 days after injection, the opposite is true for hippocampus and amygdala. This study showed that stable isotope tracer experiments can be combined with laser ablation MC-ICP-MS to measure trace element kinetics in tissues at a microscale level.

Patterns of local and nonlocal water resource use across the western U.S. determined via stable isotope intercomparisons

USDA-ARS?s Scientific Manuscript database

The stable isotope ratios of hydrogen (H) and oxygen (O) are valuable tracers of the origin of biological materials and water sources. Application of these environmental tracers is largely based on the distinct and pervasive spatial patterns of precipitation isotopes, which are preserved in many hy...

Stable water isotopes suggest sub-canopy water recycling in a northern forested catchment

Treesearch

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

2015-01-01

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

Using water stable isotopes to assess evaporation and water residence time of lakes in EPA’s National Lakes Assessment.

EPA Science Inventory

Stable isotopes of water (18O and 2H) can be very useful in large-scale monitoring programs because water samples are easy to collect and water isotopes integrate information about basic hydrological processes such as evaporation as a percentage of inflow (E/I), w...

Application of stable isotope (δ13C and δ18O) composition of mollusc shells in palaeolimnological studies - possibilities and limitations

NASA Astrophysics Data System (ADS)

Apolinarska, Karina; Pełechaty, Mariusz; Kossler, Annette; Pronin, Eugeniusz; Noskowiak, Daria

2017-04-01

Carbon (δ13C) and oxygen (δ18O) stable isotope analyses are among the standard methods applied in the studies of past environment, including climate. In lacustrine sediments, δ13C and δ18O values can be measured in fine carbonate fraction (carbonate mud), in charophyte encrustations, ostracod carapaces and mollusc shells. Application of the stable isotope record of each of the above-mentioned components of the lake sediment requires knowledge about possibilities and limitations of the method. The present research discusses the most important results of the studies carried out between 2011 and 2013, concentrated on the stable isotope composition of snail shells, primarily, the species commonly preserved in central European Quaternary lacustrine sediments. The stable isotope studies involved also, the zebra mussel (Dreissena polymorpha), one of the most invasive freshwater species in the world. The research involved shell isotope studies of both recent (Apolinarska, 2013; Apolinarska et al., 2016; Apolinarska and Pełechaty, in press) and fossil molluscs derived from the Holocene sediments (Apolinarska et al., 2015a, b). Shell δ13C values were species-specific and among the gastropods studied the same order of species from the most to the least 13C-depleted was observed at all sites sampled. Shell δ18O values were more uniform. The wide range of δ13C and δ18O values were observed in population and subpopulation, i.e. when live snails were sampled live from restricted area within the lake littoral zone. Carbon and oxygen stable isotope values of the mono-specific shells sampled from 1 cm thick sediment samples were highly variable. Those intra-specific differences (n=20) were as large as several permill. Such significant variability in δ13C and δ18O values indicates that stable isotope composition of single shells is unlikely to be representative of the sediment sample. In conclusion, samples of freshwater molluscs for stable isotope analyses should be monospecific and composed of at least several shells. The number of shells being dependent on the difference between the minimum and maximum values within the sediment layer. The research was funded by the Polish Ministry of Science and Higher Education, Iuventus Plus Program, grant No. IP2010 000670. Apolinarska, K., 2013. Stable isotope compositions of recent Dreissena polymorpha (Pallas) shells: paleoenvironmental implications. Journal of Paleolimnology 50, 353-364. Apolinarska, K., Pełechaty, M. & Kossler, A., 2015a. Within-sample variability of δ13C and δ18O values of freshwater gastropod shells and the optimum number of shells to measure per sediment layer in the Paddenluch palaeolacustrine sequence, Germany. Journal of Paleolimnology 54, 305-323. Apolinarska, K., Pełechaty, M. & Noskowiak, D., 2015b. Differences in stable isotope compositions of freshwater snails from surface sediments of two Polish shallow lakes. Limnologica 53, 95-105. Apolinarska, K., Pełechaty, M. & Pronin, E., 2016. Discrepancies between the stable isotope compositions of water, macrophyte carbonates and organics, and mollusc shells in the littoral zone of a charophyte-dominated lake (Lake Lednica, Poland). Hydrobiologia 768, 1-17. Apolinarska, K. & Pełechaty, M., Inter- and intra-specific variability in δ13C and δ18O values of freshwater gastropod shells from Lake Lednica, western Poland. DOI: 10.1515/agp-2016-0028

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

EPA Science Inventory

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

IsoNose - Isotopic Tools as Novel Sensors of Earth Surfaces Resources - A new Marie Curie Initial Training Network

NASA Astrophysics Data System (ADS)

von Blanckenburg, Friedhelm; Bouchez, Julien; Bouman, Caludia; Kamber, Balz; Gaillardet, Jérôme; Gorbushina, Anna; James, Rachael; Oelkers, Eric; Tesmer, Maja; Ashton, John

2015-04-01

The Marie Curie Initial Training Network »Isotopic Tools as Novel Sensors of Earth Surfaces Resources - IsoNose« is an alliance of eight international partners and five associated partners from science and industry. The project is coordinated at the Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences and will run until February 2018. In the last 15 years advances in novel mass-spectrometric methods have opened opportunities to identify "isotopic fingerprints" of virtually all metals and to make use of the complete information contained in these fingerprints. The understanding developed with these new tools will ultimately guide the exploitation of Earth surface environments. However, progress in bringing these methods to end-users depends on a multi transfer of knowledge between (1) isotope Geochemistry and Microbiology, Environmental Sciences (2), Economic Geology and (3) instrument developers and users in the development of user-friendly and new mass spectrometric methods. IsoNose will focus on three major Earth surface resources: soil, water and metals. These resources are currently being exploited to an unprecedented extent and their efficient management is essential for future sustainable development. Novel stable isotope techniques will disclose the processes generating (e.g. weathering, mineral ore formation) and destroying (e.g. erosion, pollution) these resources. Within this field the following questions will be addressed and answered: - How do novel stable isotope signatures characterize weathering processes? - How do novel stable isotope signatures trace water transport? - How to use novel stable isotope as environmental tracers? - How to use novel stable isotope for detecting and exploring metal ores? - How to improve analytical capabilities and develop robust routine applications for novel stable isotopes? Starting from the central questions mentioned above the IsoNose activities are organized in five scientific work packages: 1. Making soil from rock 2. Dissolved metals in the global water cycle 3. Human influence on metal cycling 4. Innovations in metal ore exploration 5. New analytical tools Acknowledgement: The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013/ under REA grant agreement n° [608069].

Applications of Cavity Ring-Down Spectroscopy (CRDS) to Analysis of Carbon Stable Isotope Composition of Groundwater

NASA Astrophysics Data System (ADS)

Jeong, T.; Woo, N. C.; Choi, H.

2014-12-01

Carbon Capture and Storage (CCS) has been considered as an effective strategy to reduce atmospheric carbon dioxide (CO2) concentration. However, unintended leakage of CO2 leakage from storage sites could occur through highly permeable conduits such as fractures in low-K formations during the injection and storage of SCCO2 (supercritical phase CO2). Therefore, prediction and detection of CO2 leakage and relevant analysis of carbon isotope are crucial to assure environmental and public safety. Until recently, Isotope Ratio Mass Spectrometry (IRMS) has been utilized to measure the stable isotope ratio of water. However, IRMS is time-consuming operation due to complicated pretreatment, and thus not a practical methodology under field conditions. Carbon Isotope Analyzer (CCIA), which is a kind of Cavity Ring-Down Spectroscopy (CRDS) and has a wide measurement range from 300 to 25000 ppmv, can facilitate the rate of measurements up to 1 Hz by using continuous flow method so that it can be readily applied to field. In this study, carbon stable isotope ratio of groundwater will be analyzed using CCIA. Then, the CCIA results will be compared with IRMS to validate its accuracy and stability. This research will provide an appropriate method for analyzing carbon stable isotope in groundwater, using a continuous flow mode.

First stable isotope analysis of Asiatic wild ass tail hair from the Mongolian Gobi.

PubMed

Horacek, Micha; Sturm, Martina Burnik; Kaczensky, Petra

Stable isotope analysis has become a powerful tool to study feeding ecology, water use or movement pattern in contemporary, historic and ancient species. Certain hair and teeth grow continuously, and when sampled longitudinally can provide temporally explicit information on dietary regime and movement pattern. In an initial trial, we analysed a tail sample of an Asiatic wild ass ( Equus hemionus ) from the Mongolian Gobi. We found seasonal variations in H, C and N isotope patterns, likely being the result of temporal variations in available feeds, water supply and possibly physiological status. Thus stable isotope analysis shows promise to study the comparative ecology of the three autochthonous equid species in the Mongolian Gobi.

Tracking Estuary Habitat use by Young American Shad Using Stable Isotopes

EPA Science Inventory

We developed and evaluated a stable isotope turnover model to estimate the probable risidence time of young-of-year (YOY) American shad (Alosa sapidissima), an anadromous clupeid, in various estuarine habitats.

Letter Report: Stable Hydrogen and Oxygen Isotope Analysis of B-Complex Groundwater Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Brady D.; Moran, James J.; Nims, Megan K.

Report summarizing stable oxygen and hydrogen isotope analysis of two groundwater samples from the B-Complex. Results from analyses were compared to perched water and pore water analyses performed previously.

Elemental and isotopic imaging of biological samples using NanoSIMS.

PubMed

Kilburn, Matt R; Clode, Peta L

2014-01-01

With its low detection limits and the ability to analyze most of the elements in the periodic table, secondary ion mass spectrometry (SIMS) represents one of the most versatile in situ analytical techniques available, and recent developments have resulted in significant advantages for the use of imaging mass spectrometry in biological and biomedical research. Increases in spatial resolution and sensitivity allow detailed interrogation of samples at relevant scales and chemical concentrations. Advances in dynamic SIMS, specifically with the advent of NanoSIMS, now allow the tracking of stable isotopes within biological systems at subcellular length scales, while static SIMS combines subcellular imaging with molecular identification. In this chapter, we present an introduction to the SIMS technique, with particular reference to NanoSIMS, and discuss its application in biological and biomedical research.

Antimony isotopic composition in river waters affected by ancient mining activity.

PubMed

Resongles, Eléonore; Freydier, Rémi; Casiot, Corinne; Viers, Jérôme; Chmeleff, Jérôme; Elbaz-Poulichet, Françoise

2015-11-01

In this study, antimony (Sb) isotopic composition was determined in natural water samples collected along two hydrosystems impacted by historical mining activities: the upper Orb River and the Gardon River watershed (SE, France). Antimony isotope ratio was measured by HG-MC-ICP-MS (Hydride Generation Multi-Collector Inductively Coupled Plasma Mass Spectrometer) after a preconcentration and purification step using a new thiol-cellulose powder (TCP) procedure. The external reproducibility obtained for δ(123)Sb measurements of our in-house Sb isotopic standard solution and a certified reference freshwater was 0.06‰ (2σ). Significant isotopic variations were evident in surface waters from the upper Orb River (-0.06‰≤δ(123)Sb≤+0.11‰) and from the Gardon River watershed (+0.27‰≤δ(123)Sb≤+0.83‰). In particular, streams that drained different former mining sites exploited for Sb or Pb-Zn exhibited contrasted Sb isotopic signature, that may be related to various biogeochemical processes occurring during Sb transfer from rocks, mine wastes and sediments to the water compartment. Nevertheless, Sb isotopic composition appeared to be stable along the Gardon River, which might be attributed to the conservative transport of Sb at distance from mine-impacted streams, due to the relative mobile behavior of Sb(V) in natural oxic waters. This study suggests that Sb isotopic composition could be a useful tool to track pollution sources and/or biogeochemical processes in hydrologic systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Using chromium stable isotope ratios to quantify Cr(VI) reduction: Lack of sorption effects

USGS Publications Warehouse

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

2004-01-01

Chromium stable isotope values can be effectively used to monitor reduction of Cr(VI) in natural waters. We investigate effects of sorption during transport of Cr(VI) which may also shift Cr isotopes values, complicating efforts to quantify reduction. This study shows that Cr stable isotope fractionation caused by sorption is negligible. Equilibrium fractionation of Cr stable isotopes between dissolved Cr-(VI) and Cr(VI) adsorbed onto ??-Al2O3 and goethite is less than 0.04???. (53Cr/52Cr) under environmentally relevant pH conditions. Batch experiments at pH 4.0 and pH 6.0 were conducted in series to sequentially magnify small isotope fractionations. A simple transport model suggests that adsorption may cause amplification of a small isotope fractionation along extreme fringes of a plume, leading to shifts in 53Cr/52Cr values. We therefore suggest that isotope values at extreme fringes of Cr plumes be critically evaluated for sorption effects. A kinetic effect was observed in experiments with goethite at pH 4 where apparently lighter isotopes diffuse into goethite clumps at a faster rate before eventually reaching equilibrium. This observed kinetic effect may be important in a natural system that has not attained equilibrium and is in need of further study. Cr isotope fractionation caused by speciation of Cr(VI) between HCrO4- and CrO42- was also examined, and we conclude that it is not measurable. In the absence of isotope fractionation caused by equilibrium speciation and sorption, most of the variation in ??53 Cr values may be attributed to reduction, and reliable estimates of Cr reduction can be made.

Quantification of in Situ Biodegradation Rate Constants Using a Novel Combined Isotope Approach

NASA Astrophysics Data System (ADS)

Blum, P.; Sültenfuß, J.; Martus, P.

2014-12-01

Numerous studies have shown the enormous potential of the compound-specific isotope analysis (CSIA) for studying the biodegradation of organic compounds such as monoaromatic hydrocarbons (BTEX), polyaromatic hydrocarbons (PAH), chlorinated solvents and other organic contaminants and environmental transformation mechanisms in groundwater. In addition, two-dimensional isotope analysis such as carbon and hydrogen have been successfully studied indicating the potential to also investigate site-specific reaction mechanisms. The main objective of the current study however is to quantify real effective in situ biodegradation rate constants in a coal-tar contaminated aquifer by combining compound-specific isotope analysis (CSIA) and tracer-based (3H-3He) ground-water dating (TGD). Hence, groundwater samples are used to determine groundwater residence times, and carbon and hydrogen stable isotopes are analyzed for selected BTEX and PAH. The results of the hydrogen stable isotopes surprisingly indicate no isotope fractionation and therefore no biodegradation. In contrast, for stable carbon isotopes of selected BTEX such as o-xylene and toluene, isotope shifts are detected indicating active biodegradation under sulfate-reducing conditions. These and previous results of stable carbon isotopes show that only for o-xylene a clear evidence for biodegradation is possible for the studied site. Nevertheless, in combining these results with the groundwater residence times, which range between 1 year for the shallow wells (20 m below surface) and 41 years for the deeper wells (40 m below surface), it is feasible to effectively determine in situ biodegradation rate constants for o-xylene. Conversely, the outcome also evidently demonstrate the major limitations of the novel combined isotope approach for a successful implementation of monitored natural attenuation (MNA) at such field sites.

Determination of the δ15N of total nitrogen in solids; RSIL lab code 2893

USGS Publications Warehouse

Revesz, Kinga; Qi, Haiping; Coplen, Tyler B.

2006-01-01

The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2893 is to determine the δ(15N/14N), abbreviated as δ15N , of total nitrogen in solid samples. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total nitrogen in a solid sample into N2 gas. The EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines relative difference in the isotope-amount ratios of stable nitrogen isotopes (15N/14N)of the product N2 gas. The combustion is quantitative; no isotopic fractionation is involved. Samples are placed in a tin capsule and loaded into the Costech Zero Blank Autosampler of the EA. Under computer control, samples are dropped into a heated reaction tube that contains an oxidant, where the combustion takes place in a helium atmosphere containing an excess of oxygen gas. Combustion products are transported by a helium carrier through a reduction tube to remove excess oxygen and convert all nitrous oxides into N2 and through a drying tube to remove water. The gas-phase products, mainly CO2 and N2, are separated by a gas chromatograph. The gas is then introduced into the isotope-ratio mass spectrometer (IRMS) through a Finnigan MAT (now Thermo Scientific) ConFlo II interface, which also is used to inject N2 reference gas and helium for sample dilution. The IRMS is a Thermo Scientific Delta V Plus CF-IRMS. It has a universal triple collector, two wide cups with a narrow cup in the middle, capable of measuring mass/charge (m/z) 28, 29, 30, simultaneously. The ion beams from N2 are as follows: m/z 28 = N2 = 14N14N; m/z 29 = N2 = 14N15N primarily; m/z 30 = NO = 14N16O primarily, which is a sign of contamination or incomplete reduction.

Stable Isotopic signatures of Adélie penguin remains provide long-term paleodietary records in Northern Victoria Land (Ross Sea, Antarctica)

NASA Astrophysics Data System (ADS)

Lorenzini, Sandra; Baroni, Carlo; Fallick, Anthony Edward; Baneschi, Ilaria; Salvatore, Maria Cristina; Zanchetta, Giovanni; Dallai, Luigi

2010-05-01

The stable isotopes geochemistry of carbon and nitrogen provides a powerful tools for investigating in animal dietary patterns and shifts during the past. The signature of C and N isotopes provide direct information about the diet of an individual and its dietary patterns, especially when the dietary sources consist of prey from different trophic levels (i.e. different C and N isotopic composition) (DeNiro and Epstein 1978, Minawaga and Wada 1984, Koch et al. 1994, Hobson 1995). By analyzing the isotopic composition of penguin remains, we present a new detailed Adélie penguin (Pygoscelis adeliae) paleodietary record for the area of Terra Nova Bay (Victoria Land, Ross Sea). Adélie penguins primarily feed on fish (mainly the silverfish Pleuragramma antarcticum) and krill (Euphausia superba, Euphausia cristallorophias) (Ainley 2002, Lorenzini et al. 2009) that belonging to two different trophic levels. Consequently, they are characterized by different isotopic signatures. Specifically, we analyzed 13C/12C and 15N/14N ratios of more than one thousand of modern and fossil Adélie penguin eggshell and guano samples collected from ornithogenic soils (penguin guano-formed) dated back to ≈7,200 years BP (Baroni and Orombelli 1994, Lambert et al. 2002, Baroni and Hall 2004, Hall et al. 2006). The expanded database of stable isotope values obtained from Adélie penguin remains define a detailed paleodietary record with an excellent temporal continuity over all the investigated time period. Our data indicate a significant dietary shift between fish and krill, with a gradual decrease from past to present time in the proportion of fish compared to krill in Adélie penguin diet. From 7200 yrs BP to 2000 yrs BP, δ13C and δ15N values indicate fish as the most eaten prey. The dietary contribution of lower-trophic prey in penguin diet started becoming evident not earlier than 2000 yrs BP, when the δ13C values reveal a mixed diet based on fish and krill consumption. Modern eggshell and guano δ15N values document a major dietary contribution of krill but not a krill-dominated diet, since δ13C values remain much too high if krill prevail in the diet. According to the Holocene environmental background attested for Victoria Land, Adélie penguin dietary shifts between fish and krill seem to reflect penguin paleoecological responses to different paleoenvironmental setting with different conditions of sea-ice extension and persistence. References Baroni C, Hall BL (2004) A new Holocene relative sea-level curve for Terra Nova Bay, Victoria Land, Antarctica. J Quaternary Sci 19:377-396. Baroni C, Orombelli G (1994) Abandoned penguin rookeries as Holocene paleoclimatic indicators in Antarctica. Geology 22:23-26. DeNiro MJ, Epstein S (1978) Influences of diet on the distribution of carbon isotopes in animals. Geochim Cosmochim Ac 42(5):495-506. Hall BL, Hoelzel AR, Baroni C, Denton GH, Le Boeuf BJ, Overturf B, Töpf AL (2006) Holocene elephant seal distribution implies warmer-than-present climate in the Ross Sea. P Natl Acad Sci Usa 103:10213-10217. Hobson KA (1995) Reconstructing avian diets using stable-carbon and nitrogen isotope analysis of egg components: patterns of isotopic fractionation and turnover. The Condor 97:752-762. Koch PL, Fogel ML, Tuross N (1994) Tracing the diet of fossil animals using stable isotopes. Pages 63-92 in K. Lajtha and R. H. Michener, editors. Stable isotopes in ecology and environmental science. Blackwell Scientific Publications, USA. Lambert DM, Ritchie PA, Millar CD, Holland B, Drummond AJ, Baroni C (2002) Rates of evolution in Ancient DNA from Adélie Penguins. Science 295:2270-2273. Lorenzini S, Olmastroni S, Pezzo F, Salvatore MC, Baroni C (2009) Holocene Adélie penguin diet in Victoria Land, Antarctica. Polar Biol 32:1077-1086. Minagawa M, Wada E (1984) Stepwise enrichment of δ15N along food chains: further evidence and the relation between δ15N and animal age. Geochim Cosmochim Ac 48:1135-1140.

Multiple stable isotope fronts during non-isothermal fluid flow

NASA Astrophysics Data System (ADS)

Fekete, Szandra; Weis, Philipp; Scott, Samuel; Driesner, Thomas

2018-02-01

Stable isotope signatures of oxygen, hydrogen and other elements in minerals from hydrothermal veins and metasomatized host rocks are widely used to investigate fluid sources and paths. Previous theoretical studies mostly focused on analyzing stable isotope fronts developing during single-phase, isothermal fluid flow. In this study, numerical simulations were performed to assess how temperature changes, transport phenomena, kinetic vs. equilibrium isotope exchange, and isotopic source signals determine mineral oxygen isotopic compositions during fluid-rock interaction. The simulations focus on one-dimensional scenarios, with non-isothermal single- and two-phase fluid flow, and include the effects of quartz precipitation and dissolution. If isotope exchange between fluid and mineral is fast, a previously unrecognized, significant enrichment in heavy oxygen isotopes of fluids and minerals occurs at the thermal front. The maximum enrichment depends on the initial isotopic composition of fluid and mineral, the fluid-rock ratio and the maximum change in temperature, but is independent of the isotopic composition of the incoming fluid. This thermally induced isotope front propagates faster than the signal related to the initial isotopic composition of the incoming fluid, which forms a trailing front behind the zone of transient heavy oxygen isotope enrichment. Temperature-dependent kinetic rates of isotope exchange between fluid and rock strongly influence the degree of enrichment at the thermal front. In systems where initial isotope values of fluids and rocks are far from equilibrium and isotope fractionation is controlled by kinetics, the temperature increase accelerates the approach of the fluid to equilibrium conditions with the host rock. Consequently, the increase at the thermal front can be less dominant and can even generate fluid values below the initial isotopic composition of the input fluid. As kinetics limit the degree of isotope exchange, a third front may develop in kinetically limited systems, which propagates with the advection speed of the incoming fluid and is, therefore, traveling fastest. The results show that oxygen isotope signatures at thermal fronts recorded in rocks and veins that experienced isotope exchange with fluids can easily be misinterpreted, namely if bulk analytical techniques are applied. However, stable isotope microanalysis on precipitated minerals may - if later isotope exchange is kinetically limited - provide a valuable archive of the transient thermal and hydrological evolution of a system.

[Progress in stable isotope labeled quantitative proteomics methods].

PubMed

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

2013-06-01

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

Stable Isotope Values of Nitrogen and Carbon in Particulate ...

EPA Pesticide Factsheets

Data set from “Patterns in stable isotope values of nitrogen and carbon in particulate matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras” by Oczkowski et al. These are the data upon which all results and conclusion are made. Publishing the data allow for use by wider audience. Stable isotope dynamics on the shelf can inform both nearshore and open ocean research efforts, providing an important link along the marine continuum. To our knowledge, this data set is unique in its spatial coverage and variables measured.

USE OF SLACK-WATER ENVIRONMENTS BY COHO SALMON JUVENILES IN A COASTAL OREGON STREAM AS INDICATED BY 34S STABLE ISOTOPE ANALYSIS

EPA Science Inventory

Stable isotopes of sulfur are rarely used in studies of elemental cycling, trophic position or use of marine-derived nutrients by salmonids. The main reason for this probably is the reluctance on the part of isotope labs to expose their instruments to SO2 (because of its corrosi...

IRMS to study a common cocaine cutting agent: phenacetin.

PubMed

Ladroue, Virginie; Dujourdy, Laurence; Besacier, Fabrice; Jame, Patrick

2017-03-01

Phenacetin is a pharmaceutical closely related to acetaminophen that has been banned in France for a long time due to its nephritic and carcinogenic adverse effects. It frequently appears in cocaine seizures as a cutting agent. Following both sanitary and intelligence motivations, this molecule was chosen for this study, and stable isotopes seemed to be the most appropriate tool. A total of 228 seized samples were collected over a 6-year period, and 8 standards of known origin were purchased. They were submitted to gas chromatography (GC) or elemental analysis - isotope ratio mass spectrometry (EA-IRMS) measurements, depending on their complexity. Stable isotope ratios of carbon, hydrogen, and nitrogen for a part of the sample set, were acquired. The isotopic values of phenacetin standards acquired from various providers located worldwide are quite spread, which indicates that stable isotopes could be used to discriminate manufacturers. However, the measured values of most of the seized samples are concentrated in a narrow range, tending to demonstrate that phenacetin is smuggled from a single source or similar ones. Consequently, stable isotopes could only be used to exclude that several samples come from a common source. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Lipid Extraction Techniques for Stable Isotope Analysis and Ecological Assays.

PubMed

Elliott, Kyle H; Roth, James D; Crook, Kevin

2017-01-01

Lipid extraction is an important component of many ecological and ecotoxicological measurements. For instance, percent lipid is often used as a measure of body condition, under the assumption that those individuals with higher lipid reserves are healthier. Likewise, lipids are depleted in 13 C compared with protein, and it is consequently a routine to remove lipids prior to measuring carbon isotopes in ecological studies so that variation in lipid content does not obscure variation in diet. We provide detailed methods for two different protocols for lipid extraction: Soxhlet apparatus and manual distillation. We also provide methods for polar and nonpolar solvents. Neutral (nonpolar) solvents remove some lipids but few non-lipid compounds, whereas polar solvents remove most lipids but also many non-lipid compounds. We discuss each of the methods and provide guidelines for best practices. We recommend that, for stable isotope analysis, researchers test for a relationship between the change in carbon stable isotope ratio and the amount of lipid extracted to see if the degree of extraction has an impact on isotope ratios. Stable isotope analysis is widely used by ecologists, and we provide a detailed methodology that minimizes known biases.

Extreme Monsoon Rainfall Signatures Preserved in the Invasive Terrestrial Gastropod Lissachatina fulica

NASA Astrophysics Data System (ADS)

Ghosh, Prosenjit; Rangarajan, Ravi; Thirumalai, Kaustubh; Naggs, Fred

2017-11-01

Indian summer monsoon (ISM) rainfall lasts for a period of 4 months with large variations recorded in terms of rainfall intensity during its period between June and September. Proxy reconstructions of past ISM rainfall variability are required due to the paucity of long instrumental records. However, reconstructing subseasonal rainfall is extremely difficult using conventional hydroclimate proxies due to inadequate sample resolution. Here, we demonstrate the utility of the stable oxygen isotope composition of gastropod shells in reconstructing past rainfall on subseasonal timescales. We present a comparative isotopic study on present day rainwater and stable isotope ratios of precipitate found in the incremental growth bands of giant African land snail Lissachatina fulica (Bowdich) from modern day (2009) and in the historical past (1918). Isotopic signatures present in the growth bands allowed for the identification of ISM rainfall variability in terms of its active and dry spells in the modern as well as past gastropod record. Our results demonstrate the utility of gastropod growth band stable isotope ratios in semiquantitative reconstructions of seasonal rainfall patterns. High resolution climate records extracted from gastropod growth band stable isotopes (museum and archived specimens) can expand the scope for understanding past subseasonal-to-seasonal climate variability.

Evaluating the use of stable isotope analysis to infer the feeding ecology of a growing US gray seal (Halichoerus grypus) population.

PubMed

Lerner, Jacob E; Ono, Kathryn; Hernandez, Keith M; Runstadler, Jonathan A; Puryear, Wendy B; Polito, Michael J

2018-01-01

Gray seals (Halichoerus grypus) have been rapidly recolonizing the Northeast US coast, eliciting concern from the fishing industry. However, the ecological effect of this recovery is still unknown and as such, research is needed to better understand how the diet composition of gray seals in US waters will contribute to the ecological impact. While previous research on seal diets has focused on the analysis of hard prey remains, stable isotope analysis presents an alternative method that can be used to describe marine mammal diets when direct observation is impossible. To address this issue, we used stable isotope analysis of gray seal pup vibrissae and lanugo from Monomoy Island, Cape Cod, MA during the 2015/2016 winter breeding season to estimate adult female diet composition during pregnancy. Stable isotope mixing models (SIMM) suggested adult female gray seals were consuming greater amounts of cephalopod prey and less sand lance than previously indicated from analysis of hard prey remains. However, using SIMMs to estimate the diet composition of gray seals remains difficult due to the large number of isotopically similar prey species and uncertainty in tissue-specific, stable isotope trophic enrichment factors. Even so, by combining prey sources into ecologically informative groups and integrating prior information into SIMMs it is possible to obtain additional insights into the diet of this generalist predator.

Possible Food Sources of Macrozoobenthos in the Manko Mangrove Ecosystem, Okinawa (Japan): A Stable Isotope Analysis Approach

PubMed Central

Wardiatno, Yusli; Mardiansyah; Prartono, Tri; Tsuchiya, Makoto

2015-01-01

Identifying potential food sources in mangrove ecosystems is complex because of the multifarious inputs from both land and sea. This study, which was conducted in the Manko mangrove ecosystem of Okinawa, Japan, determined the composition of the stable isotopes δ13C and δ15N in primary producers and macrozoobenthos to estimate the potential food sources assimilated and to elucidate the target trophic levels of the macrozoobenthos. We measured the two stable isotope signatures of three gastropods (Cerithidea sp., Cassidula mustelina, Peronia verruculata), two crabs (Grapsidae sp., Uca sp.), mangrove tree (Kandelia candel) leaves, and sediment from the mangrove ecosystem. The respective carbon and nitrogen isotope signature results were as follows: −22.4‰ and 8.6‰ for Cerithidea sp., −25.06‰ and 8‰ for C. mustelina, −22.58‰ and 8‰ for P. verruculata, −24.3‰ and 10.6‰ for unidentified Grapsidae, −21.87 ‰ and 11.5 ‰ for Uca sp., −29.81‰ and 11‰ for K. candel, and −24.23‰ and 7.2‰ for the sediment. The stable isotope assimilation signatures of the macrozoobenthos indicated sediment as their food source. Considering the trophic levels, the stable isotope values may also indicate that the five macrozoobenthos species were secondary or higher consumers. PMID:26019747

Pollution and Climate Effects on Tree-Ring Nitrogen Isotopes

NASA Astrophysics Data System (ADS)

Savard, M. M.; Bégin, C.; Marion, J.; Smirnoff, A.

2009-04-01

BACKGROUND Monitoring of nitrous oxide concentration only started during the last 30 years in North America, but anthropogenic atmospheric nitrogen has been significantly emitted over the last 150 years. Can geochemical characteristics of tree rings be used to infer past changes in the nitrogen cycle of temperate regions? To address this question we use nitrogen stable isotopes in 125 years-long ring series from beech specimens (Fagus grandifolia) of the Georgian Bay Islands National Park (eastern Ontario), and pine (Pinus strobus) and beech trees of the Arboretum Morgan near Montreal (western Quebec). To evaluate the reliability of the N stable isotopes in wood treated for removal of soluble materials, we tested both tree species from the Montreal area. The reproducibility from tree to tree was excellent for both pine and beech trees, the isotopic trends were strongly concordant, and they were not influenced by the heartwood-sapwood transition zone. The coherence of changes of the isotopic series observed for the two species suggests that their tree-ring N isotopic values can serve as environmental indicator. RESULTS AND INTERPRETATION In Montreal and Georgian Bay, the N isotopes show strong and similar parallel agreement (Gleichlaufigkeit test) with the climatic parameters. So in fact, the short-term isotopic fluctuations correlate directly with summer precipitation and inversely with summer and spring temperature. A long-term decreasing isotope trend in Montreal indicates progressive changes in soil chemistry after 1951. A pedochemical change is also inferred for the Georgian Bay site on the basis of a positive N isotopic trend initiated after 1971. At both sites, the long-term ^15N series correlate with a proxy for NOx emissions (Pearson correlation), and carbon-isotope ring series suggest that the same trees have been impacted by phytotoxic pollutants (Savard et al., 2009a). We propose that the contrasted long-term nitrogen-isotope changes of Montreal and Georgian Bay reflect deposition of NOx emissions from cars and coal-power plants, with higher proportions from coal burning in Georgian Bay (Savard et al., 2009b). This interpretation is conceivable because recent monitoring indicates that coal-power plant NOx emissions play an important role in the annual N budget in Ontario, but they are negligible on the Quebec side. CONCLUSION Interpretations of long tree-ring N isotopic series in terms of effects generated by airborne N-species have been previously advocated. Here we further propose that the contrasted isotopic trends obtained for wood samples from two regions reflect different regional anthropogenic N deposition combined with variations of climatic conditions. This research suggests that nitrogen tree-ring series may record both regional climatic conditions and anthropogenic perturbations of the N cycle. REFERENCES Savard, M.M., Bégin,C., Marion, J., Aznar, J.-C., Smirnoff, A., 2009a. Changes of Air Quality in an urban region as inferred from tree-ring width and stable isotopes. Chapter 9 in "Relating Atmospheric Source Apportionment to Vegetation Effects: Establishing Cause Effect Relationships" (A. Legge ed.). Elsevier, Amsterdam; doi: 10.1016/S1474-8177(08)00209x. Savard, M.M., Bégin, C., Smirnoff, A., Marion, J., Rioux-Paquette, E., 2009b. Tree-ring nitrogen isotopes reflect climatic effects and anthropogenic NOx emissions. Env. Sci. Tech (doi: 10.1021/es802437k).

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

PubMed Central

Gillespie, J. Hayley

2013-01-01

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

La–Ce isotope measurements by multicollector-ICPMS† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7ja00256d

PubMed Central

Münker, Carsten; Strub, Erik

2017-01-01

The 138La–138Ce decay system (half-life 1.02 × 1011 years) is a potentially highly useful tool to unravel information about the timing of geological processes and about the interaction of geological reservoirs on earth, complementing information from the more popular 147Sm–143Nd and 176Lu–176Hf isotope systems. Previously published analytical protocols were limited to TIMS. Here we present for the first time an analytical protocol that employs MC-ICPMS, with an improved precision and sensitivity. To perform sufficiently accurate La–Ce measurements, an efficient ion-chromatographic procedure is required to separate Ce from the other rare earth elements (REE) and Ba quantitatively. This study presents an improved ion-chromatographic procedure that separates La and Ce from rock samples using a three-step column separation. After REE separation by cation exchange, Ce is separated employing an Ln Spec column and selective oxidation. In the last step, a cation clean-up chemistry is performed to remove all remaining interferences. Our MC-ICPMS measurement protocol includes all stable Ce isotopes (136Ce, 138Ce, 140Ce and 142Ce), by employing a 1010 ohm amplifier for the most abundant isotope 140Ce. An external reproducibility of ±0.25ε-units (2 r.s.d) has been routinely achieved for 138Ce measurements for as little as 150–600 ng Ce, depending on the sample–skimmer cone combinations being used. Because the traditionally used JMC-304 Ce reference material is not commercially available anymore, a new reference material was prepared from AMES laboratory Ce metal (Cologne-AMES). In order to compare the new material with the previously reported isotopic composition of AMES material prepared at Mainz (Mainz-AMES), Cologne-AMES and JMC-304 were measured relative to each other in the same analytical session, demonstrating isotope heterogeneity between the two AMES and different JMC-304 batches used in the literature. To enable sufficiently precise age correction of radiogenic 138Ce and to perform isochron dating, a protocol was developed where La and Ce concentrations are determined by isotope dilution (ID), using an isotope tracer enriched in 138La and 142Ce. The new protocols were applied to determine the variations of Ce isotope compositions and La–Ce concentrations of certified geochemical reference materials (CRMs): BCR-2, BCR-1, BHVO-2, JR-1, JA-2, JB-3, JG-1, JR-1, JB-1b, AGV-1 and one in-house La Palma standard. PMID:29456283

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

NASA Astrophysics Data System (ADS)

Horton, Travis W.; Defliese, William F.; Tripati, Aradhna K.; Oze, Christopher

2016-01-01

Growing pressure on sustainable water resource allocation in the context of global development and rapid environmental change demands rigorous knowledge of how regional water cycles change through time. One of the most attractive and widely utilized approaches for gaining this knowledge is the analysis of lake carbonate stable isotopic compositions. However, endogenic carbonate archives are sensitive to a variety of natural processes and conditions leaving isotopic datasets largely underdetermined. As a consequence, isotopic researchers are often required to assume values for multiple parameters, including temperature of carbonate formation or lake water δ18O, in order to interpret changes in hydrologic conditions. Here, we review and analyze a global compilation of 57 lacustrine dual carbon and oxygen stable isotope records with a topical focus on the effects of shifting hydrologic balance on endogenic carbonate isotopic compositions. Through integration of multiple large datasets we show that lake carbonate δ18O values and the lake waters from which they are derived are often shifted by >+10‰ relative to source waters discharging into the lake. The global pattern of δ18O and δ13C covariation observed in >70% of the records studied and in several evaporation experiments demonstrates that isotopic fractionations associated with lake water evaporation cause the heavy carbon and oxygen isotope enrichments observed in most lakes and lake carbonate records. Modeled endogenic calcite compositions in isotopic equilibrium with lake source waters further demonstrate that evaporation effects can be extreme even in lake records where δ18O and δ13C covariation is absent. Aridisol pedogenic carbonates show similar isotopic responses to evaporation, and the relevance of evaporative modification to paleoclimatic and paleotopographic research using endogenic carbonate proxies are discussed. Recent advances in stable isotope research techniques present unprecedented opportunities to overcome the underdetermined nature of stable isotopic data through integration of multiple isotopic proxies, including dual element 13C-excess values and clumped isotope temperature estimates. We demonstrate the utility of applying these multi-proxy approaches to the interpretation of paleohydroclimatic conditions in ancient lake systems. Understanding past, present, and future hydroclimatic systems is a global imperative. Significant progress should be expected as these modern research techniques become more widely applied and integrated with traditional stable isotopic proxies.

The Geochemical Databases GEOROC and GeoReM - What's New?

NASA Astrophysics Data System (ADS)

Sarbas, B.; Jochum, K. P.; Nohl, U.; Weis, U.

2017-12-01

The geochemical databases GEOROC (http: georoc.mpch-mainz.gwdg.de) and GeoReM (http: georem.mpch-mainz.gwdg.de) are maintained by the Max Planck Institute for Chemistry in Mainz, Germany. Both online databases became crucial tools for geoscientists from different research areas. They are regularly upgraded by new tools and new data from recent publications obtained from a wide range of international journals. GEOROC is a collection of published analyses of volcanic rocks and mantle xenoliths. Since recently, data for plutonic rocks are added. The analyses include major and trace element concentrations, radiogenic and non-radiogenic isotope ratios as well as analytical ages for whole rocks, glasses, minerals and inclusions. Samples come from eleven geological settings and span the whole geological age scale from Archean to Recent. Metadata include, among others, geographic location, rock class and rock type, geological age, degree of alteration, analytical method, laboratory, and reference. The GEOROC web page allows selection of samples by geological setting, geography, chemical criteria, rock or sample name, and bibliographic criteria. In addition, it provides a large number of precompiled files for individual locations, minerals and rock classes. GeoReM is a database collecting information about reference materials of geological and environmental interest, such as rock powders, synthetic and natural glasses as well as mineral, isotopic, biological, river water and seawater reference materials. It contains published data and compilation values (major and trace element concentrations and mass fractions, radiogenic and stable isotope ratios). Metadata comprise, among others, uncertainty, analytical method and laboratory. Reference materials are important for calibration, method validation, quality control and to establish metrological traceability. GeoReM offers six different search strategies: samples or materials (published values), samples (GeoReM preferred values), chemical criteria, chemical criteria based on bibliography, bibliography, as well as methods and institutions.

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

EPA Science Inventory

We used stable isotope (δ13C, 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...

Using Redwood Tree Ring Chronologies to Obtain the Long-View on California's Coastal Climate

NASA Astrophysics Data System (ADS)

Dawson, T. E.; Roden, J. S.; Voelker, S. L.; Johnstone, J. A.; Ambrose, A.

2014-12-01

Coast redwood (Sequoia sempervirens) occupies a long and narrow range at the land-sea interface from the southern Big Bur region to the California-Oregon boarder. Since mature trees can live in excess of 2000 years, using the interannual variability in the oxygen and carbon stable isotope composition of tree rings obtained from trees growing in different parts of the redwood range holds the potential for obtaining a long-term record of California's coastal climate, including the history of temperatures, low cloud / fog, rainfall and associated climatic drivers of their variation. We analyzed the oxygen and carbon stable isotope composition of tree ring cellulose from both tree cores and whole cross-sectional slabs and compared these data to several regional climate indicies and to published growth chronologies to obtain the long-view on California's coastal climate. Several highlights will be presented and discussed. These include: (1) redwoods faithfully record water sources they use in the oxygen stable isotope composition of their tree ring cellulose; (2) these is both strong watershed- and regional-scale coherence; (3) redwood tree ring carbon isotope composition shows its strongest correlations to tree water status, stand-scale humidity, and at the regional scale to what we term "summer precipitation" anomalies (lack of rain with presence of fog); also (4) that carbon stable isotope composition is very sensitive to within tree and stand microclimate while oxygen stable isotope composition seems to be sensitive to topographic site factors like slope position and proximity to riparian / gully habitats; (5) multivariate climatic analyses reveal that summertime drought recorded in the isotope excursions are most strongly linked to atmospheric circulation anomalies; and (6) that redwood tree rings and their isotope composition provide great potential for reconstructing high-resolution paleo-climate along the California coast.

Platinum stable isotopes in ferromanganese crust and nodules

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

Stable-isotope analysis: a neglected tool for placing parasites in food webs.

PubMed

Sabadel, A J M; Stumbo, A D; MacLeod, C D

2018-02-28

Parasites are often overlooked in the construction of food webs, despite their ubiquitous presence in almost every type of ecosystem. Researchers who do recognize their importance often struggle to include parasites using classical food-web theory, mainly due to the parasites' multiple hosts and life stages. A novel approach using compound-specific stable-isotope analysis promises to provide considerable insight into the energetic exchanges of parasite and host, which may solve some of the issues inherent in incorporating parasites using a classical approach. Understanding the role of parasites within food webs, and tracing the associated biomass transfers, are crucial to constructing new models that will expand our knowledge of food webs. This mini-review focuses on stable-isotope studies published in the past decade, and introduces compound-specific stable-isotope analysis as a powerful, but underutilized, newly developed tool that may answer many unresolved questions regarding the role of parasites in food webs.

Determining origin in a migratory marine vertebrate: a novel method to integrate stable isotopes and satellite tracking

USGS Publications Warehouse

Vander Zanden, Hannah B.; Tucker, Anton D.; Hart, Kristen M.; Lamont, Margaret M.; Fujisaki, Ikuko; Addison, David S.; Mansfield, Katherine L.; Phillips, Katrina F.; Wunder, Michael B.; Bowen, Gabriel J.; Pajuelo, Mariela; Bolten, Alan B.; Bjorndal, Karen A.

2015-01-01

Stable isotope analysis is a useful tool to track animal movements in both terrestrial and marine environments. These intrinsic markers are assimilated through the diet and may exhibit spatial gradients as a result of biogeochemical processes at the base of the food web. In the marine environment, maps to predict the spatial distribution of stable isotopes are limited, and thus determining geographic origin has been reliant upon integrating satellite telemetry and stable isotope data. Migratory sea turtles regularly move between foraging and reproductive areas. Whereas most nesting populations can be easily accessed and regularly monitored, little is known about the demographic trends in foraging populations. The purpose of the present study was to examine migration patterns of loggerhead nesting aggregations in the Gulf of Mexico (GoM), where sea turtles have been historically understudied. Two methods of geographic assignment using stable isotope values in known-origin samples from satellite telemetry were compared: 1) a nominal approach through discriminant analysis and 2) a novel continuous-surface approach using bivariate carbon and nitrogen isoscapes (isotopic landscapes) developed for this study. Tissue samples for stable isotope analysis were obtained from 60 satellite-tracked individuals at five nesting beaches within the GoM. Both methodological approaches for assignment resulted in high accuracy of foraging area determination, though each has advantages and disadvantages. The nominal approach is more appropriate when defined boundaries are necessary, but up to 42% of the individuals could not be considered in this approach. All individuals can be included in the continuous-surface approach, and individual results can be aggregated to identify geographic hotspots of foraging area use, though the accuracy rate was lower than nominal assignment. The methodological validation provides a foundation for future sea turtle studies in the region to inexpensively determine geographic origin for large numbers of untracked individuals. Regular monitoring of sea turtle nesting aggregations with stable isotope sampling can be used to fill critical data gaps regarding habitat use and migration patterns. Probabilistic assignment to origin with isoscapes has not been previously used in the marine environment, but the methods presented here could also be applied to other migratory marine species.

Determining origin in a migratory marine vertebrate: a novel method to integrate stable isotopes and satellite tracking.

PubMed

Zanden, Hannah B Vander; Tucker, Anton D; Hart, Kristen M; Lamont, Margaret M; Fuisaki, Ikuko; Addison, David; Mansfield, Katherine L; Phillips, Katrina F; Wunder, Michael B; Bowen, Gabriel J; Pajuelo, Mariela; Bolten, Alan B; Bjorndal, Karen A

2015-03-01

Stable isotope analysis is a useful tool to track animal movements in both terrestrial and marine environments. These intrinsic markers are assimilated through the diet and may exhibit spatial gradients as a result of biogeochemical processes at the base of the food web. In the marine environment, maps to predict the spatial distribution of stable isotopes are limited, and thus determining geographic origin has been reliant upon integrating satellite telemetry and stable isotope data. Migratory sea turtles regularly move between foraging and reproductive areas. Whereas most nesting populations can be easily accessed and regularly monitored, little is known about the demographic trends in foraging populations. The purpose of the present study was to examine migration patterns of loggerhead nesting aggregations in the Gulf of Mexico (GoM), where sea turtles have been historically understudied. Two methods of geographic assignment using stable isotope values in known-origin samples from satellite telemetry were compared: (1) a nominal approach through discriminant analysis and (2) a novel continuous-surface approach using bivariate carbon and nitrogen isoscapes (isotopic landscapes) developed for this study. Tissue samples for stable isotope analysis were obtained from 60 satellite-tracked individuals at five nesting beaches within the GoM. Both methodological approaches for assignment resulted in high accuracy of foraging area determination, though each has advantages and disadvantages. The nominal approach is more appropriate when defined boundaries are necessary, but up to 42% of the individuals could not be considered in this approach. All individuals can be included in the continuous-surface approach, and individual results can be aggregated to identify geographic hotspots of foraging area use, though the accuracy rate was lower than nominal assignment. The methodological validation provides a foundation for future sea turtle studies in the region to inexpensively determine geographic origin for large numbers of untracked individuals. Regular monitoring of sea turtle nesting aggregations with stable isotope sampling can be used to fill critical data gaps regarding habitat use and migration patterns. Probabilistic assignment to origin with isoscapes has not been previously used in the marine environment, but the methods presented here could also be applied to other migratory marine species.

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

NASA Astrophysics Data System (ADS)

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

2008-12-01

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

EasyDelta: A spreadsheet for kinetic modeling of the stable carbon isotope composition of natural gases

NASA Astrophysics Data System (ADS)

Zou, Yan-Rong; Wang, Lianyuan; Shuai, Yanhua; Peng, Ping'an

2005-08-01

A new kinetic model and an Excel © spreadsheet program for modeling the stable carbon isotope composition of natural gases is provided in this paper. The model and spreadsheet could be used to describe and predict the variances in stable carbon isotope of natural gases under both experimental and geological conditions with heating temperature or geological time. It is a user-friendly convenient tool for the modeling of isotope variation with time under experimental and geological conditions. The spreadsheet, based on experimental data, requires the input of the kinetic parameters of gaseous hydrocarbons generation. Some assumptions are made in this model: the conventional (non-isotope species) kinetic parameters represent the light isotope species; the initial isotopic value is the same for all parallel chemical reaction of gaseous hydrocarbons generation for simplicity, the re-exponential factor ratio, 13A/ 12A, is a constant, and both heavy and light isotope species have similar activation energy distribution. These assumptions are common in modeling of isotope ratios. The spreadsheet is used for searching the best kinetic parameters of the heavy isotope species to reach the minimum errors compared with experimental data, and then extrapolating isotopic changes to the thermal history of sedimentary basins. A short calculation example on the variation in δ13C values of methane is provided in this paper to show application to geological conditions.

Urban water - a new frontier in isotope hydrology.

PubMed

Ehleringer, James R; Barnette, Janet E; Jameel, Yusuf; Tipple, Brett J; Bowen, Gabriel J

2016-01-01

Isotope hydrology has focused largely on landscapes away from densely inhabited regions. In coming decades, it will become increasingly more important to focus on water supplies and dynamics within urban systems. Stable isotope analyses provide important information to water managers within large cities, particularly in arid regions where evaporative histories of water sources, vulnerabilities, and reliabilities of the water supplies can be major issues. Here the spatial and vertical understanding of water supporting urban systems that comes from stable isotope analyses can serve as a useful management tool. We explore this research frontier using the coupled natural-human landscape of the Salt Lake Valley, USA, with its greater than one million inhabitants. We first provide data on the stable isotope ratios of the hydrologic system's primary components: precipitation, incoming surface waters, and terminus waters in this closed basin. We then explore the spatial and temporal patterns of drinking waters within the urban landscape and the new opportunities to better link isotope ratio data with short- and long-term management interests of water managers.

Stable carbon and nitrogen isotope ratios of sodium and potassium cyanide as a forensic signature.

PubMed

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

2012-01-01

Sodium and potassium cyanide are highly toxic, produced in large amounts by the chemical industry, and linked to numerous high-profile crimes. The U.S. Centers for Disease Control and Prevention has identified cyanide as one of the most probable agents to be used in a chemical terrorism event. We investigated whether stable C and N isotopic content of sodium and potassium cyanide could serve as a forensic signature for sample matching, using a collection of 65 cyanide samples. Upon analysis, a few of the cyanide samples displayed nonhomogeneous isotopic content associated with degradation to a carbonate salt and loss of hydrogen cyanide. Most samples had highly reproducible isotope content. Of the 65 cyanide samples, >95% could be properly matched based on C and N isotope ratios, with a false match rate <3%. These results suggest that stable C and N isotope ratios are a useful forensic signature for matching cyanide samples. © 2011 American Academy of Forensic Sciences.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruzer, Helen W; Horita, Juske; Moran, James J

2012-01-01

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

Association between Nitrogen Stable Isotope Ratios in Human Hair and Serum Levels of Leptin.

PubMed

Ahn, Song Vogue; Koh, Sang-Baek; Lee, Kwang-Sik; Bong, Yeon-Sik; Park, Jong-Ku

2017-10-01

Stable isotope ratios have been reported to be potential biomarkers of dietary intake and nutritional status. High serum levels of leptin, a hormone which regulates energy metabolism and food intake, are associated with insulin resistance and metabolic syndrome. However, little is known about the association between stable isotope ratios and the metabolic risk in humans. We investigated whether the carbon and nitrogen stable isotope ratios in hair are associated with serum leptin levels. Hair samples were collected from 399 healthy adults (233 men and 166 women) aged 40 to 70 years of a community-based cohort in Korea and the bulk stable isotope ratios of carbon (δ 13 C) and nitrogen (δ 15 N) were measured for all hair samples. Serum leptin levels were analyzed by radioimmunoassay. δ 15 N showed positive correlations with serum leptin levels. In multivariate models, increasing δ 15 N were associated with elevated serum leptin levels (defined as ≥ the median values), whereas δ 13 C were not significantly associated with serum leptin levels. The odds ratio (95% confidence interval) per 1‰ increase in δ 15 N for an elevated serum leptin level was 1.58 (1.11-2.26). In participants with high body mass index, δ 15 N showed positive associations with serum leptin levels, whereas these associations were not seen in participants with low body mass index. The nitrogen stable isotopic ratio in hair is positively associated with serum leptin levels. The hair δ 15 N could be used as a clinical marker to estimate metabolic risk.

Early Proterozoic crustal evolution: Geochemical and NdPb isotopic evidence from metasedimentary rocks, southwestern North America

NASA Astrophysics Data System (ADS)

McLennan, S. M.; Hemming, S. R.; Taylor, S. R.; Eriksson, K. A.

1995-03-01

Early Proterozoic (1.8-1.7 Ga) metasedimentary rocks in northern New Mexico and southern Colorado, USA, can be divided into turbidite successions (commonly volcanogenic) associated with mafic/felsic metavolcanic successions (e.g., Irving Fm.) and stable shelf quartzite-pelite successions of shallow marine origin (e.g., Hondo Gp.). Metapelites from the turbidite successions reported here have low K2O/Na2O, low Th/U (<3.0), low to moderate Th/Sc (0.1-0.6), and slight negative Eu-anomalies, although regionally, negative Eu-anomalies in such rocks are common. At the time of sedimentation (ca. 1.7-1.8 Ga), ɛNd values were in the range +3 to +7, indistinguishable from associated metavolcanic and plutonic rocks. Similarly, lead isotopic data scatter about a 1.7 Ga reference isochron. Low κ (232Th/238U) values for the Irving Formation are consistent with derivation from crustal sources similar to the southern Colorado/northern New Mexico lead isotope crustal province. These data are further consistent with a volcanic arc related origin. In contrast, stable shelf metapelites have high K2O/Na2O, variable but commonly high Th/U (2.0-7.0), moderate to high Th/Sc (0.5-1.4), and substantial negative Eu-anomalies. Although compositions are rather variable, they are typical of post-Archean shales. Neodymium isotopes are surprisingly radiogenic with ɛNd(1.7 Ga) in the range -0.2 to +4. Lead isotopic data for the least radiogenic samples also are consistent with a dominantly juvenile source and on a 207Pb/204Pb vs. 206Pb/204Pb diagram, data scatter slightly above the 1.7 Ga reference isochron, suggesting minor components of significantly older material. Lead isotopic systematics suggest that a major component of the provenance was derived from the immediately associated metavolcanic-plutonic terranes, consistent with suggestions of a first-cycle origin, but with an Archean component. Isotopic data restrict the Archean component to about 10%, on average, and no more than 25% in any sample. This older crustal component may be derived either by direct erosion of Archean rocks, such as the Wyoming Province, or indirectly through assimilation into Early Proterozoic igneous rocks. Although the stable shelf sedimentary rocks are derived from a provenance with similar ages as the volcanogenic turbidites, the geochemical characteristics of the provenance are significantly different. Accordingly, these data are consistent with especially rapid and widespread crustal growth and evolution in southwestern North America during the period 1.9-1.7 Ga. Several samples from the Hondo Group and Uncompahgre Formation have REE patterns that are rotated to LREE depletion and perhaps HREE enrichment. The change in REEs correlate with Mo, U, and V abundances and Pb isotopic characteristics suggesting sedimentary processes similar to those operating in black shales affected these REE patterns. REE patterns and Th/U ratios of Early Proterozoic volcanogenic turbidites examined in this and other studies differ on average from turbidites found in Archean greenstone belts. Negative Eu-anomalies are common, HREE-depletion is seen but comparatively rare, and Th/U ratios are commonly below 3.0. Accordingly, these data are consistent with models suggesting that the upper crust had a different composition in the Archean.

Seasonal variations in the stable carbon isotopic signature of biogenic methane in a coastal sediment

NASA Technical Reports Server (NTRS)

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

1986-01-01

Systematic seasonal variations in the stable carbon isotopic signature of methane gas occur in the anoxic sediments of Cape Lookout Bight, a lagoonal basin on North Carolina's Outer Banks. Values for the carbon isotope ratio of methane range from -57.3 per mil during summer to -68.5 per mil during winter in gas bubbles with an average methane content of 95 percent. The variations are hypothesized to result from changes in the pathways of microbial methane production and cycling of key substrates including acetate and hydrogen. The use of stable isotopic signatures to investigate the global methane cycle through mass balance calculations, involving various sediment and soil biogenic sources, appears to require seasonally averaged data from individual sites.

First stable isotope analysis of Asiatic wild ass tail hair from the Mongolian Gobi

PubMed Central

Horacek, Micha; Sturm, Martina Burnik; Kaczensky, Petra

2015-01-01

Stable isotope analysis has become a powerful tool to study feeding ecology, water use or movement pattern in contemporary, historic and ancient species. Certain hair and teeth grow continuously, and when sampled longitudinally can provide temporally explicit information on dietary regime and movement pattern. In an initial trial, we analysed a tail sample of an Asiatic wild ass (Equus hemionus) from the Mongolian Gobi. We found seasonal variations in H, C and N isotope patterns, likely being the result of temporal variations in available feeds, water supply and possibly physiological status. Thus stable isotope analysis shows promise to study the comparative ecology of the three autochthonous equid species in the Mongolian Gobi. PMID:26339116

Stable isotope evidence for increasing dietary breadth in the European mid-Upper Paleolithic

PubMed Central

Richards, Michael P.; Pettitt, Paul B.; Stiner, Mary C.; Trinkaus, Erik

2001-01-01

New carbon and nitrogen stable isotope values for human remains dating to the mid-Upper Paleolithic in Europe indicate significant amounts of aquatic (fish, mollusks, and/or birds) foods in some of their diets. Most of this evidence points to exploitation of inland freshwater aquatic resources in particular. By contrast, European Neandertal collagen carbon and nitrogen stable isotope values do not indicate significant use of inland aquatic foods but instead show that they obtained the majority of their protein from terrestrial herbivores. In agreement with recent zooarcheological analyses, the isotope results indicate shifts toward a more broad-spectrum subsistence economy in inland Europe by the mid-Upper Paleolithic period, probably associated with significant population increases. PMID:11371652

Stable isotope evidence for increasing dietary breadth in the European mid-Upper Paleolithic.

PubMed

Richards, M P; Pettitt, P B; Stiner, M C; Trinkaus, E

2001-05-22

New carbon and nitrogen stable isotope values for human remains dating to the mid-Upper Paleolithic in Europe indicate significant amounts of aquatic (fish, mollusks, and/or birds) foods in some of their diets. Most of this evidence points to exploitation of inland freshwater aquatic resources in particular. By contrast, European Neandertal collagen carbon and nitrogen stable isotope values do not indicate significant use of inland aquatic foods but instead show that they obtained the majority of their protein from terrestrial herbivores. In agreement with recent zooarcheological analyses, the isotope results indicate shifts toward a more broad-spectrum subsistence economy in inland Europe by the mid-Upper Paleolithic period, probably associated with significant population increases.

High-precision isotopic characterization of USGS reference materials by TIMS and MC-ICP-MS

NASA Astrophysics Data System (ADS)

Weis, Dominique; Kieffer, Bruno; Maerschalk, Claude; Barling, Jane; de Jong, Jeroen; Williams, Gwen A.; Hanano, Diane; Pretorius, Wilma; Mattielli, Nadine; Scoates, James S.; Goolaerts, Arnaud; Friedman, Richard M.; Mahoney, J. Brian

2006-08-01

The Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia has undertaken a systematic analysis of the isotopic (Sr, Nd, and Pb) compositions and concentrations of a broad compositional range of U.S. Geological Survey (USGS) reference materials, including basalt (BCR-1, 2; BHVO-1, 2), andesite (AGV-1, 2), rhyolite (RGM-1, 2), syenite (STM-1, 2), granodiorite (GSP-2), and granite (G-2, 3). USGS rock reference materials are geochemically well characterized, but there is neither a systematic methodology nor a database for radiogenic isotopic compositions, even for the widely used BCR-1. This investigation represents the first comprehensive, systematic analysis of the isotopic composition and concentration of USGS reference materials and provides an important database for the isotopic community. In addition, the range of equipment at the PCIGR, including a Nu Instruments Plasma MC-ICP-MS, a Thermo Finnigan Triton TIMS, and a Thermo Finnigan Element2 HR-ICP-MS, permits an assessment and comparison of the precision and accuracy of isotopic analyses determined by both the TIMS and MC-ICP-MS methods (e.g., Nd isotopic compositions). For each of the reference materials, 5 to 10 complete replicate analyses provide coherent isotopic results, all with external precision below 30 ppm (2 SD) for Sr and Nd isotopic compositions (27 and 24 ppm for TIMS and MC-ICP-MS, respectively). Our results also show that the first- and second-generation USGS reference materials have homogeneous Sr and Nd isotopic compositions. Nd isotopic compositions by MC-ICP-MS and TIMS agree to within 15 ppm for all reference materials. Interlaboratory MC-ICP-MS comparisons show excellent agreement for Pb isotopic compositions; however, the reproducibility is not as good as for Sr and Nd. A careful, sequential leaching experiment of three first- and second-generation reference materials (BCR, BHVO, AGV) indicates that the heterogeneity in Pb isotopic compositions, and concentrations, could be directly related to contamination by the steel (mortar/pestle) used to process the materials. Contamination also accounts for the high concentrations of certain other trace elements (e.g., Li, Mo, Cd, Sn, Sb, W) in various USGS reference materials.

Investigation of Chemical and Physical Changes to Bioapatite During Fossilization Using Trace Element Geochemistry, Infrared Spectroscopy and Stable Isotopes

NASA Astrophysics Data System (ADS)

Suarez, C. A.; Kohn, M. J.

2013-12-01

Bioapatite in the form of vertebrate bone can be used for a wide variety of paleo-proxies, from determination of ancient diet to the isotopic composition of meteoric water. Bioapatite alteration during diagenesis is a constant barrier to the use of fossil bone as a paleo-proxy. To elucidate the physical and chemical alteration of bone apatite during fossilization, we analyzed an assortment of fossil bones of different ages for trace elements, using LA-ICP-MS, stable isotopes, and reflected IR spectroscopy. One set of fossil bones from the Pleistocene of Idaho show a diffusion recrystallization profile, however, rare earth element (REE) profiles indicate diffusion adsorption. This suggests that REE diffusion is controlled by changing (namely decreasing) boundary conditions (i.e. decreasing concentration of REE in surrounding pore fluids). Reflected IR analysis along this concentration profile reveal that areas high in U have lost type A carbonate from the crystal structure in addition to water and organics. Stable isotopic analysis of carbon and oxygen will determine what, if any, change in the isotopic composition of the carbonate component of apatite has occurred do to the diffusion and recrystallization process. Analysis of much older bone from the Cretaceous of China reveal shallow REE and U concentration profiles and very uniform reflected IR spectra with a significant loss of type A carbonate throughout the entire bone cortex. Analysis of stable isotopes through the bone cortex will be compared to the stable isotopes collected from the Pleistocene of Idaho.

Relation of Phanerozoic stable isotope excursions to climate, bacterial metabolism, and major extinctions

PubMed Central

Stanley, Steven M.

2010-01-01

Conspicuous global stable carbon isotope excursions that are recorded in marine sedimentary rocks of Phanerozoic age and were associated with major extinctions have generally paralleled global stable oxygen isotope excursions. All of these phenomena are therefore likely to share a common origin through global climate change. Exceptional patterns for carbon isotope excursions resulted from massive carbon burial during warm intervals of widespread marine anoxic conditions. The many carbon isotope excursions that parallel those for oxygen isotopes can to a large degree be accounted for by the Q10 pattern of respiration for bacteria: As temperature changed along continental margins, where ∼90% of marine carbon burial occurs today, rates of remineralization of isotopically light carbon must have changed exponentially. This would have reduced organic carbon burial during global warming and increased it during global cooling. Also contributing to the δ13C excursions have been release and uptake of methane by clathrates, the positive correlation between temperature and degree of fractionation of carbon isotopes by phytoplankton at temperatures below ∼15°, and increased phytoplankton productivity during “icehouse” conditions. The Q10 pattern for bacteria and climate-related changes in clathrate volume represent positive feedbacks for climate change. PMID:21041682

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 ...

Stable isotope estimates of evaporation: inflow and water residence time for lakes across the United States as a tool for national lake water quality assessments

EPA Science Inventory

Stable isotope ratios of water (delta18O and delta2H) can be very useful in large-scale monitoring programs because water samples are easy to collect and isotope ratios integrate information about basic hydrologic processes such as evaporation as a percentage of inflow (E/I) and ...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasmussen, K.A.; Neumann, A.C.; Haddad, R.I.

The stable-isotope composition ({delta}{sup 13}C) of total organic carbon (TOC) was measured as a function of depth throughout a 217-cm-thick sequence of Holocene carbonate sediment within the Bight of Abaco lagoon, Little Bahama Bank. Biofacies and lithofacies analyses indicate progressive banktop submergence and paleoenvironmental response during Holocene sea-level rise. Stable-isotope values shift markedly from {minus}27.7{per thousand} within the 7900 B.P. paleosol at the base of the core to {minus}11.1{per thousand} at the present-day sediment-water interface. An abrupt excursion toward heavy-isotope values records the first establishment of Thalassia seagrass upon open-marine flooding. A multitracer approach, combining biofacies, lithofacies, and stable-isotope analysismore » of TOC confirms that the dramatic +17{per thousand} shift observed in {delta}{sup 13}C was a direct result of sea-level rise and associated environmental changes over the banktop; there is little evidence of spurious diagenetic overprint. Stable-isotope analyses of organic carbon may enhance the reconstruction of carbonate sequences by revealing a distinctive geochemical signature of banktop flooding, including the onset of growth of otherwise unpreservable Thalassia seagrass.« less

Stable isotope measurements of evapotranspiration partitioning in a maize field

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

Estimating pathway-specific contributions to biodegradation in aquifers based on dual isotope analysis: theoretical analysis and reactive transport simulations.

PubMed

Centler, Florian; Heße, Falk; Thullner, Martin

2013-09-01

At field sites with varying redox conditions, different redox-specific microbial degradation pathways contribute to total contaminant degradation. The identification of pathway-specific contributions to total contaminant removal is of high practical relevance, yet difficult to achieve with current methods. Current stable-isotope-fractionation-based techniques focus on the identification of dominant biodegradation pathways under constant environmental conditions. We present an approach based on dual stable isotope data to estimate the individual contributions of two redox-specific pathways. We apply this approach to carbon and hydrogen isotope data obtained from reactive transport simulations of an organic contaminant plume in a two-dimensional aquifer cross section to test the applicability of the method. To take aspects typically encountered at field sites into account, additional simulations addressed the effects of transverse mixing, diffusion-induced stable-isotope fractionation, heterogeneities in the flow field, and mixing in sampling wells on isotope-based estimates for aerobic and anaerobic pathway contributions to total contaminant biodegradation. Results confirm the general applicability of the presented estimation method which is most accurate along the plume core and less accurate towards the fringe where flow paths receive contaminant mass and associated isotope signatures from the core by transverse dispersion. The presented method complements the stable-isotope-fractionation-based analysis toolbox. At field sites with varying redox conditions, it provides a means to identify the relative importance of individual, redox-specific degradation pathways. © 2013.

A Collaborative Study: Determination of Mycotoxins in Corn, Peanut Butter, and Wheat Flour Using Stable Isotope Dilution Assay (SIDA) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).

PubMed

Zhang, Kai; Schaab, Matthew R; Southwood, Gavin; Tor, Elizabeth R; Aston, Linda S; Song, Wenlu; Eitzer, Brian; Majumdar, Sanghamitra; Lapainis, Theodore; Mai, Huy; Tran, Kevin; El-Demerdash, Aref; Vega, Victor; Cai, Yanxuan; Wong, Jon W; Krynitsky, Alexandra J; Begley, Timothy H

2017-08-23

A collaborative study was conducted to evaluate stable isotope dilution assay (SIDA) and LC-MS/MS for the simultaneous determination of aflatoxins B 1 , B 2 , G 1 , and G 2 ; deoxynivalenol; fumonisins B 1 , B 2 , and B 3 ; ochratoxin A; HT-2 toxin; T-2 toxin; and zearalenone in foods. Samples were fortified with 12 13 C uniformly labeled mycotoxins ( 13 C-IS) corresponding to the native mycotoxins and extracted with acetonitrile/water (50:50 v/v), followed by centrifugation, filtration, and LC-MS/MS analysis. In addition to certified reference materials, the six participating laboratories analyzed corn, peanut butter, and wheat flour fortified with the 12 mycotoxins at concentrations ranging from 1.0 to 1000 ng/g. Using their available LC-MS/MS platform, each laboratory developed in-house instrumental conditions for analysis. The majority of recoveries ranged from 80 to 120% with relative standard derivations (RSDs) <20%. Greater than 90% of the average recoveries of the participating laboratories were in the range of 90-110%, with repeatability RSD r (within laboratory) < 10% and reproducibility RSD R (among laboratory) < 15%. All Z scores of the results of certified reference materials were between -2 and 2. Using 13 C-IS eliminated the need for matrix-matched calibration standards for quantitation, simplified sample preparation, and achieved simultaneous identification and quantitation of multiple mycotoxins in a simple LC-MS/MS procedure.

Ecological structure and function in a restored versus natural salt marsh

PubMed Central

Rezek, Ryan J.; Lebreton, Benoit; Sterba-Boatwright, Blair

2017-01-01

Habitat reconstruction is commonly employed to restore degraded estuarine habitats and lost ecological functions. In this study, we use a combination of stable isotope analyses and macrofauna community analysis to compare the ecological structure and function between a recently constructed Spartina alterniflora salt marsh and a natural reference habitat over a 2-year period. The restored marsh was successful in providing habitat for economically and ecologically important macrofauna taxa; supporting similar or greater density, biomass, and species richness to the natural reference during all but one sampling period. Stable isotope analyses revealed that communities from the natural and the restored marshes relied on a similar diversity of food resources and that decapods had similar trophic levels. However, some generalist consumers (Palaemonetes spp. and Penaeus aztecus) were more 13C-enriched in the natural marsh, indicating a greater use of macrophyte derived organic matter relative to restored marsh counterparts. This difference was attributed to the higher quantities of macrophyte detritus and organic carbon in natural marsh sediments. Reduced marsh flooding frequency was associated with a reduction in macrofaunal biomass and decapod trophic levels. The restored marsh edge occurred at lower elevations than natural marsh edge, apparently due to reduced fetch and wind-wave exposure provided by the protective berm structures. The lower elevation of the restored marsh edge mitigated negative impacts in sampling periods with low tidal elevations that affected the natural marsh. The results of this study highlight the importance of considering sediment characteristics and elevation in salt marsh constructions. PMID:29261795

Mercury concentrations in fish from forest harvesting and fire-impacted Canadian Boreal lakes compared using stable isotopes of nitrogen.

PubMed

Garcia, Edenise; Carignan, Richard

2005-03-01

Total mercury (Hg) concentration was determined in several piscivorous and nonpiscivorous species of fish from 38 drainage lakes with clear-cut, burnt, or undisturbed catchments located in the Canadian Boreal Shield. Mercury concentrations increased with increasing fish trophic position as estimated using stable isotopes of nitrogen (N; r2 = 0.52, 0.49, and 0.30 for cut, reference, and burnt lakes, respectively; p < 0.01). Mercury biomagnification per thousand delta15N varied from 22 to 29% in the three groups of lakes. Mercury availability to organisms at the base of the food chain in lakes with cut catchments was higher than that in reference lakes. In cut lakes, Hg concentrations in fish were significantly related to ratio of the clear-cut area to lake area (or lake volume; r = +0.82 and +0.74, respectively, p < 0.01). Both impact ratios were, in turn, significantly correlated with dissolved organic carbon. These findings suggest that differential loading of organic matter-bound Hg to lakes can affect Hg cycling. In addition, Hg concentrations exceeded the advisory limit for human consumption (0.5 microg/g wet wt) from the World Health Organization in all top predatory species (northern pike, walleye, and burbot) found in cut and in two partially burnt lakes. Thus, high Hg concentrations in fish from forest-harvested and partially burnt lakes may reflect increased exposure to Hg relative to that in lakes not having these watershed disturbances.

Bacterial Degraders of Coexisting Dichloromethane, Benzene, and Toluene, Identified by Stable-Isotope Probing.

PubMed

Yoshikawa, Miho; Zhang, Ming; Kurisu, Futoshi; Toyota, Koki

2017-01-01

Most bioremediation studies on volatile organic compounds (VOCs) have focused on a single contaminant or its derived compounds and degraders have been identified under single contaminant conditions. Bioremediation of multiple contaminants remains a challenging issue. To identify a bacterial consortium that degrades multiple VOCs (dichloromethane (DCM), benzene, and toluene), we applied DNA-stable isotope probing. For individual tests, we combined a 13 C-labeled VOC with other two unlabeled VOCs, and prepared three unlabeled VOCs as a reference. Over 11 days, DNA was periodically extracted from the consortia, and the bacterial community was evaluated by next-generation sequencing of bacterial 16S rRNA gene amplicons. Density gradient fractions of the DNA extracts were amplified by universal bacterial primers for the 16S rRNA gene sequences, and the amplicons were analyzed by terminal restriction fragment length polymorphism (T-RFLP) using restriction enzymes: Hha I and Msp I. The T-RFLP fragments were identified by 16S rRNA gene cloning and sequencing. Under all test conditions, the consortia were dominated by Rhodanobacter , Bradyrhizobium / Afipia , Rhizobium , and Hyphomicrobium . DNA derived from Hyphomicrobium and Propioniferax shifted toward heavier fractions under the condition added with 13 C-DCM and 13 C-benzene, respectively, compared with the reference, but no shifts were induced by 13 C-toluene addition. This implies that Hyphomicrobium and Propioniferax were the main DCM and benzene degraders, respectively, under the coexisting condition. The known benzene degrader Pseudomonas sp. was present but not actively involved in the degradation.

Ecological structure and function in a restored versus natural salt marsh.

PubMed

Rezek, Ryan J; Lebreton, Benoit; Sterba-Boatwright, Blair; Beseres Pollack, Jennifer

2017-01-01

Habitat reconstruction is commonly employed to restore degraded estuarine habitats and lost ecological functions. In this study, we use a combination of stable isotope analyses and macrofauna community analysis to compare the ecological structure and function between a recently constructed Spartina alterniflora salt marsh and a natural reference habitat over a 2-year period. The restored marsh was successful in providing habitat for economically and ecologically important macrofauna taxa; supporting similar or greater density, biomass, and species richness to the natural reference during all but one sampling period. Stable isotope analyses revealed that communities from the natural and the restored marshes relied on a similar diversity of food resources and that decapods had similar trophic levels. However, some generalist consumers (Palaemonetes spp. and Penaeus aztecus) were more 13C-enriched in the natural marsh, indicating a greater use of macrophyte derived organic matter relative to restored marsh counterparts. This difference was attributed to the higher quantities of macrophyte detritus and organic carbon in natural marsh sediments. Reduced marsh flooding frequency was associated with a reduction in macrofaunal biomass and decapod trophic levels. The restored marsh edge occurred at lower elevations than natural marsh edge, apparently due to reduced fetch and wind-wave exposure provided by the protective berm structures. The lower elevation of the restored marsh edge mitigated negative impacts in sampling periods with low tidal elevations that affected the natural marsh. The results of this study highlight the importance of considering sediment characteristics and elevation in salt marsh constructions.

Discrimination factors of carbon and nitrogen stable isotopes from diet to hair and scat in captive tigers (Panthera tigris) and snow leopards (Uncia uncia).

PubMed

Montanari, Shaena; Amato, George

2015-06-15

In order to use stable isotope ratio values obtained from wild animal tissues, we must accurately calculate the differences in isotope ratios between diet and consumer (δtissue - δdiet). These values, called trophic discrimination factors (TDFs, denoted with ∆), are necessary for stable isotope ecology studies and are best calculated in controlled environments. Scat, hair, and diet samples were collected from captive tigers (n = 8) and snow leopards (n = 10) at the Bronx Zoo. The isotope ratios of carbon and nitrogen, the two most commonly used in ecological studies, of the samples were measured by continuous-flow isotope ratio mass spectrometry. The trophic discrimination factors were calculated for both carbon (δ(13)C values) and nitrogen (δ(15)N values). It was found that the only significant TDFs in this study were diet-hair, ∆(13)CHair, for snow leopards (5.97 ± 1.25‰) and tigers (6.45 ± 0.54‰), and diet-scat, ∆(15)NScat, in snow leopards (2.49 ± 1.30‰). The other mean isotope ratios were not significantly different from that of the premixed feline diet. The ∆(15)NHair values for both species were unusually low, potentially due to the protein content and quality of the feline diet. The discrimination factors of the stable isotopes of carbon and nitrogen calculated in this study can be applied to ecological studies of wild, non-captive terrestrial mammals. The effect of protein quality in isotope discrimination is also worthy of further investigation to better understand variation in TDFs. Carnivore scat is shown to be a valuable material for isotopic analysis. Copyright © 2015 John Wiley & Sons, Ltd.

Degradation and Volatilization of Chlorofluorocarbons in Contaminated Groundwater Explored by Stable Carbon Isotope Analysis

NASA Astrophysics Data System (ADS)

Horst, A.; Lacrampe-Couloume, G.; Sherwood Lollar, B.

2015-12-01

Chlorofluorocarbons (CFCs) are ozone depleting compounds whose production was phased out by the regulations of the Montreal Protocol (1987). Accidental release and disposal also led to contamination of groundwater at many locations, however, and this legacy persists. Although very stable, CFCs may degrade via abiotic and biotic pathways. Quantification of the degree of transformation of CFCs has been challenging due to other processes such as dilution, sorption and volatilization. Compound specific stable carbon isotope analysis (CSIA) has been successfully applied for a variety of priority pollutants to distinguish degradation from other processes and to quantify transformation rates. A Purge & Trap - CSIA method developed in our lab was applied to determine the stable carbon isotopic signature of CFCs and HCFCs (hydrochlorofluorocarbons) in groundwater samples from a contaminated site. Preliminary results suggest that degradation of CFCs and HCFCs may result in enriched δ13C values, consistent with fractionation during bond breakage as has been reported for many other hydrocarbon pollutants. The effect of volatile loss during sampling on the isotopic signatures of CFCs was examined in laboratory experiments. Volatilization from pure phase CFCs showed a small inverse isotope effect during open system volatilization, opposite to the normal isotope effect generally observed during biodegradation. For volatilization of CFCs dissolved in water a much smaller isotope effect was observed. An important result from this work is that any volatile loss may introduce only a small change in CFC isotopic signatures in groundwater, and importantly, due to the opposite direction of isotope effects associated with volatilization versus degradation, any effects of volatile loss on the isotopic signatures cannot be confused with transformation of CFCs. At most, volatilization might contribute to a conservative estimate of the extent of degradation.

Stable carbon and sulfur isotopes as records of the early biosphere

NASA Technical Reports Server (NTRS)

Desmarais, David J.

1989-01-01

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conroy, Jessica L; Cobb, Kim M; Noone, David

The objective of this field campaign was to investigate climatic controls on the stable isotopic composition of water vapor, precipitation, and seawater in the western tropical Pacific. Simultaneous measurements of the stable isotopic composition of vapor and precipitation from April 28 to May 8, 2013, at the Manus Tropical Western Pacific Atmospheric Radiation Measurement site, provided several key insights into the nature of the climate signal archived in precipitation and vapor isotope ratios. We observed a large shift from lower to higher isotopic values in vapor and precipitation because of the passage of a mesoscale convective system west of themore » site and a transition from a regional stormy period into a more quiescent period. During the quiescent period, the stable isotopic composition of vapor and precipitation indicated the predominance of oceanic evaporation in determining the isotopic composition of boundary-layer vapor and local precipitation. There was not a consistent relationship between intra-event precipitation amount at the site and the stable isotopic composition of precipitation, thus challenging simplified assumptions about the isotopic “amount effect” in the tropics on the time scale of individual storms. However, some storms did show an amount effect, and deuterium excess values in precipitation had a significant relationship with several meteorological variables, including precipitation, temperature, relative humidity, and cloud base height across all measured storms. The direction of these relationships points to condensation controls on precipitation deuterium excess values on intra-event time scales. The relationship between simultaneous measurements of vapor and precipitation isotope ratios during precipitation events indicates the ratio of precipitation-to-vapor isotope ratios can diagnose precipitation originating from a vapor source unique from boundary-layer vapor and rain re-evaporation.« less

Equilibrium stable-isotope fractionation of thallium and mercury

NASA Astrophysics Data System (ADS)

Schauble, E. A.

2005-12-01

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

Preparative separation of underivatized amino acids for compound-specific stable isotope analysis and radiocarbon dating of hydrolyzed bone collagen.

PubMed

Tripp, Jennifer A; McCullagh, James S O; Hedges, Robert E M

2006-01-01

Analysis of stable and radioactive isotopes from bone collagen provides useful information to archaeologists about the origin and age of bone artifacts. Isolation and analysis of single amino acids from the proteins can provide additional and more accurate information by removing contamination and separating a bulk isotope signal into its constituent parts. In this paper, we report a new method for the separation and isolation of underivatized amino acids from bone collagen, and their analysis by isotope ratio MS and accelerator MS. RP chromatography is used to separate the amino acids with nonpolar side chains, followed by an ion pair separation to isolate the remaining amino acids. The method produces single amino acids with little or no contamination from the separation process and allows for the measurement of accurate stable isotope ratios and pure samples for radiocarbon dating.

Applicability of stable C and N isotope analysis in inferring the geographical origin and authentication of commercial fish (Mackerel, Yellow Croaker and Pollock).

PubMed

Kim, Heejoong; Suresh Kumar, K; Shin, Kyung-Hoon

2015-04-01

Globalisation of seafood and aquaculture products and their convenient marketing worldwide, increases the possibility for the distribution of mislabelled products; thereby, underlining the need to identify their origin. Stable isotope analysis is a promising approach to identify the authenticity and traceability of seafood and aquaculture products. In this investigation, we measured carbon and nitrogen stable isotope ratios (δ(13)C and δ(15)N) of three commercial fish, viz. Mackerel, Yellow Croaker and Pollock, originating from various countries. Apart from the species-dependent variation in the isotopic values, marked differences in the δ(13)C and δ(15)N ratios were also observed with respect to the country of origin. This suggests that C and N isotopic signatures could be reliable tools to identify and trace the origin of commercial fish. Copyright © 2014 Elsevier Ltd. All rights reserved.

The study of trace metal absoption using stable isotopes and mass spectrometry

NASA Astrophysics Data System (ADS)

Fennessey, P. V.; Lloyd-Kindstrand, L.; Hambidge, K. M.

1991-12-01

The absorption and excretion of zinc stable isotopes have been followed in more than 120 human subjects. The isotope enrichment determinations were made using a standard VG 7070E HF mass spectrometer. A fast atom gun (FAB) was used to form the ions from a dry residue on a pure silver probe tip. Isotope ratio measurements were found to have a precision of better than 2% (relative standard deviation) and required a sample size of 1-5 [mu]g. The average true absorption of zinc was found to be 73 ± 12% (2[sigma]) when the metal was taken in a fasting state. This absorption figure was corrected for tracer that had been absorbed and secreted into the gastrointestinal (GI) tract over the time course of the study. The average time for a majority of the stable isotope tracer to pass through the GI tract was 4.7 ± 1.9 (2[sigma]) days.

Converting isotope ratios to diet composition - the use of mixing models - June 2010

EPA Science Inventory

One application of stable isotope analysis is to reconstruct diet composition based on isotopic mass balance. The isotopic value of a consumer’s tissue reflects the isotopic values of its food sources proportional to their dietary contributions. Isotopic mixing models are used ...

Effects of acidification on the isotopic ratios of Neotropical otter tooth dentin.

PubMed

Carrasco, Thayara S; Botta, Silvina; Machado, Rodrigo; Colares, Elton P; Secchi, Eduardo R

2018-05-30

Stable carbon and nitrogen isotope ratios are widely used in ecological studies providing important information on the trophic ecology and habitat use of consumers. However, some factors may lead to isotopic variability, which makes difficult the interpretation of data, such as the presence of inorganic carbon in mineralized tissues. In order to remove the inorganic carbon, acidification is a commonly used treatment. The effects of two methods of acidification were tested: (i) dentin acidification with 10% HCl using the 'drop-by-drop' technique, and (ii) dentin acidification in an 'HCl atmosphere', by exposing the dentin to vaporous 30% hydrochloric acid. Results were compared with untreated subsamples. The stable carbon and nitrogen ratios of untreated and acidified subsamples were measured using an elemental analyzer coupled to an isotope ratio mass spectrometer. The nitrogen isotopic ratios were statistically different between the two acidification treatments, but no significant changes in carbon isotopic ratios were found in acidified and untreated samples. The results indicated that acidification had no effect on carbon isotopic ratios of Neotropical otter tooth dentin, while introducing a source of error in nitrogen isotopic ratios. Therefore, we conclude that acidification is an unnecessary step for C and N stable isotope analysis. Copyright © 2018 John Wiley & Sons, Ltd.

Assessing the statistical robustness of inter- and intra-basinal carbon isotope chemostratigraphic correlation

NASA Astrophysics Data System (ADS)

Hay, C.; Creveling, J. R.; Huybers, P. J.

2016-12-01

Excursions in the stable carbon isotopic composition of carbonate rocks (δ13Ccarb) can facilitate correlation of Precambrian and Phanerozoic sedimentary successions at a higher temporal resolution than radiometric and biostratigraphic frameworks typically afford. Within the bounds of litho- and biostratigraphic constraints, stratigraphers often correlate isotopic patterns between distant stratigraphic sections through visual alignment of local maxima and minima of isotopic values. The reproducibility of this method can prove challenging and, thus, evaluating the statistical robustness of intrabasinal composite carbon isotope curves, and global correlations to these reference curves, remains difficult. To assess the reproducibility of stratigraphic alignment of δ13Ccarb data, and correlations between carbon isotope excursions, we employ a numerical dynamic time warping methodology that stretches and squeezes the time axis of a record to obtain an optimal correlation (in a least-squares sense) between time-uncertain series of data. In particular, we assess various alignments between series of Early Cambrian δ13Ccarb data with respect to plausible matches. We first show that an alignment of these records obtained visually, and published previously, is broadly reproducible using dynamic time warping. Alternative alignments with similar goodness of fits are also obtainable, and their stratigraphic plausibility are discussed. This approach should be generalizable to an algorithm for the purposes of developing a library of plausible alignments between multiple time-uncertain stratigraphic records.

Is the 20th century warming unprecedented in the Siberian north?

NASA Astrophysics Data System (ADS)

Sidorova, Olga V.; Saurer, Matthias; Andreev, Andrei; Fritzsche, Diedrich; Opel, Thomas; Naurzbaev, Mukhtar M.; Siegwolf, Rolf

2013-08-01

To answer the question "Has the recent warming no analogues in the Siberian north?" we analyzed larch tree samples (Larix gmelinii Rupr.) from permafrost zone in the eastern Taimyr (TAY) (72°N, 102°E) using tree-ring and stable isotope analyses for the Climatic Optimum Period (COP) 4111-3806 BC and Medieval Warm Period (MWP) 917-1150 AD, in comparison to the recent period (RP) 1791-2008 AD. We developed a description of the climatic and environmental changes in the eastern Taimyr using tree-ring width and stable isotope (δ13C, δ18O) data based on statistical verification of the relationships to climatic parameters (temperature and precipitation). Additionally, we compared our new tree-ring and stable isotope data sets with earlier published July temperature and precipitation reconstructions inferred from pollen data of the Lama Lake, Taimyr Peninsula, δ18O ice core data from Akademii Nauk ice cap on Severnaya Zemlya (SZ) and δ18O ice core data from Greenland (GISP2), as well as tree-ring width and stable carbon and oxygen isotope data from northeastern Yakutia (YAK). We found that the COP in TAY was warmer and drier compared to the MWP but rather similar to the RP. Our results indicate that the MWP in TAY started earlier and was wetter than in YAK. July precipitation reconstructions obtained from pollen data of the Lama Lake, oxygen isotope data from SZ and our carbon isotopes in tree cellulose agree well and indicate wetter climate conditions during the MWP. Consistent large-scale patterns were reflected in significant links between oxygen isotope data in tree cellulose from TAY and YAK, and oxygen isotope data from SZ and GISP2 during the MWP and the RP. Finally, we showed that the recent warming is not unprecedented in the Siberian north. Similar climate conditions were recorded by tree-rings, stable isotopes, pollen, and ice core data 6000 years ago.

Diet-tissue stable isotope (Δ(13)C and Δ(15)N) discrimination factors for multiple tissues from terrestrial reptiles.

PubMed

Steinitz, Ronnie; Lemm, Jeffrey M; Pasachnik, Stesha A; Kurle, Carolyn M

2016-01-15

Stable isotope analysis is a powerful tool for reconstructing trophic interactions to better understand drivers of community ecology. Taxon-specific stable isotope discrimination factors contribute to the best use of this tool. We determined the first Δ(13)C and Δ(15)N values for Rock Iguanas (Cyclura spp.) to better understand isotopic fractionation and estimate wild reptile foraging ecology. The Δ(13)C and Δ(15)N values between diet and skin, blood, and scat were determined from juvenile and adult iguanas held for 1 year on a known diet. We measured relationships between iguana discrimination factors and size/age and quantified effects of lipid extraction and acid treatment on stable isotope values from iguana tissues. Isotopic and elemental compositions were determined by Dumas combustion using an elemental analyzer coupled to an isotope ratio mass spectrometer using standards of known composition. The Δ(13)C and Δ(15)N values ranged from -2.5 to +6.5‰ and +2.2 to +7.5‰, respectively, with some differences among tissues and between juveniles and adults. The Δ(13)C values from blood and skin differed among species, but not the Δ(15)N values. The Δ(13)C values from blood and skin and Δ(15)N values from blood were positively correlated with size/age. The Δ(13)C values from scat were negatively correlated with size (not age). Treatment with HCl (scat) and lipid extraction (skin) did not affect the isotope values. These results should aid in the understanding of processes driving stable carbon and nitrogen isotope discrimination factors in reptiles. We provide estimates of Δ(13)C and Δ(15)N values and linear relationships between iguana size/age and discrimination factors for the best interpretation of wild reptile foraging ecology. Copyright © 2015 John Wiley & Sons, Ltd.

Modelling stable water isotopes during "high-precipitation" events at Dome C, Antarctica

NASA Astrophysics Data System (ADS)

Schlosser, Elisabeth; Masson-Delmotte, Valérie; Risi, Camille; Stenni, Barbara; Valt, Mauro; Powers, Jordan G.; Manning, Kevin W.; Duda, Michael G.; Cagnati, Anselmo

2014-05-01

For a correct paleoclimatologic interpretation of stable water isotopes from ice cores both pre- and post-depositional processes and their role for isotope fractionation have to be better understood. Our study focusses on "pre-depositional processes", namely the atmospheric processes that determine moisture transport and precipitation formation. At the deep ice core drilling site "Dome C", East Antarctica, fresh snow samples have been taken since 2006. These samples have been analysed crystallographically, which enables us to clearly distinguish between blowing snow, diamond dust, and "synoptic precipitation". Also the stable oxygen/hydrogen isotope ratios of the snow samples were measured, including measurements of 17-O. This is the first and only multi-year fresh-snow data series from an Antarctic deep drilling site. The Antarctic Mesoscale Prediction System (AMPS) employs Polar WRF for aviation weather forecasts in Antarctica. The data are archived and can be used for scientific purposes. The mesoscale atmospheric model was adapted especially for polar regions. The horizontal resolution for the domain that covers the Antarctic continent is 10 km. It was shown that precipitation at Dome C is temporally dominated by diamond dust. However, comparatively large amounts of precipitation are observed during several "high-precipitation" events per year, caused by synoptic activity in the circumpolar trough and related advection of relatively warm and moist air from lower latitudes to the interior of Antarctica. AMPS archive data are used to investigate the synoptic situations that lead to "high-precipitation" events at Dome C; in particular, possible moisture sources are determined using back-trajectories. With this meteorological information, the isotope ratios are calculated using two different isotope models, the Mixed Cloud Isotope Model, a simple Rayleigh-type model, and the LMDZ-iso (Laboratoire de Météorologie Dynamic Zoom), a General Circulation Model (GCM) with implementation of stable isotopes. The results are compared to the measured stable isotope ratios of the fresh snow samples.

Paleoproxies: Heavy Stable Isotope Perspectives

NASA Astrophysics Data System (ADS)

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

2002-12-01

Recent advances in isotope ratio mass spectrometry, namely multiple collector ICP-MS and refined TIMS techniques, will significantly enhance the ability to measure heavy stable isotope fractionation, which will lead to the development of a wide array of process-identifying (bio)-geochemical tools. Thus far research in this area is not easily assessable to scientists outside the isotope field. This is due to the fact that analyzing heavy stable isotopes does not provide routine numbers which are per se true (the preciser the truer) but is still a highly experimental field. On the other hand resolving earth science problems requires specialists familiar with the environment being studied. So what is in there for paleoceanographers? In a first order approach, relating isotope variations to physical processes is straightforward. A prominent example are oxygen isotope variations with temperature. The total geological signal is of course far more complicated. At low temperatures, heavy stable isotopes variations have been reported for e.g. Ca, Cr, Fe, Cu, Zn, Mo and Tl. Fractionation mechanisms and physical parameters responsible for the observed variations are not yet resolved for most elements. Significant equilibrium isotope fractionation is expected from redox reactions of transition metals. However a difference in coordination number between two coexisting speciations of an element in the same oxidation state can also cause fractionation. Protonation of dissolved Mo is one case currently discussed. For paleoceanography studies, a principal distinction between transition metals essential for life (V to Zn plus Mo) or not will be helpful. In case of the former group, distinction between biogenic and abiogenic isotope fractionation will remain an important issue. For example, abiotic Fe redox reactions result in isotope fractionations indistinguishable in direction and magnitude from microbial effects. Only a combination of different stable isotope systems bears the potential to solve this problem for a given set of samples and thus to model the ocean system more accurately in different scales. Besides all complications some important applications of heavy stable isotopes as paleoproxies already emerge. Pilot studies indicate that Mo isotopes may present a proxy for the extend of anoxic condition in past oceans. On a finer scale the same system appears to provide a measure of (bio)-chemical redox-changes related to diagenesis. The Ca isotope system may complement more classical sea surface temperature proxies in particular environments. Promising results exist for polar waters (N. pachy left), as well as indications on the seasonality under global greenhouse conditions ~110-50 Ma ago. However, the heavily species dependent Ca isotope fractionation can not be interpreted by just adopting concepts and findings from the oxygen system. While a complication to the ease of use as SST proxy, this species dependence offers pathways to unravel different modes of bio-calcifications. Given the complexity of the matter, collaboration of specialists of different fields will be needed to develop successful process-related hypotheses and diagnostic tools.

APPLICATION OF STABLE ISOTOPE TECHNIQUES TO AIR POLLUTION RESEARCH

EPA Science Inventory

Stable isotope techniques provide a robust, yet under-utilized tool for examining pollutant effects on plant growth and ecosystem function. Here, we survey a range of mixing model, physiological and system level applications for documenting pollutant effects. Mixing model examp...

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...

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,...

Stable isotope dimethyl labelling for quantitative proteomics and beyond

PubMed Central

Hsu, Jue-Liang; Chen, Shu-Hui

2016-01-01

Stable-isotope reductive dimethylation, a cost-effective, simple, robust, reliable and easy-to- multiplex labelling method, is widely applied to quantitative proteomics using liquid chromatography-mass spectrometry. This review focuses on biological applications of stable-isotope dimethyl labelling for a large-scale comparative analysis of protein expression and post-translational modifications based on its unique properties of the labelling chemistry. Some other applications of the labelling method for sample preparation and mass spectrometry-based protein identification and characterization are also summarized. This article is part of the themed issue ‘Quantitative mass spectrometry’. PMID:27644970

Precipitation stable isotope records from the northern Hengduan Mountains in China capture signals of the winter India-Burma Trough and the Indian Summer Monsoon

NASA Astrophysics Data System (ADS)

Yu, Wusheng; Tian, Lide; Yao, Tandong; Xu, Baiqing; Wei, Feili; Ma, Yaoming; Zhu, Haifeng; Luo, Lun; Qu, Dongmei

2017-11-01

This project reports results of the first precipitation stable isotope (δ18 O and δD) time series produced for Qamdo in the northern Hengduan Mountains in the southeastern Tibetan Plateau. The data showed that the fluctuations of precipitation stable isotopes at Qamdo during the different seasons revealed various moisture sources. The westerlies and local recycling moisture dominated at the study area before the pre-monsoon and after the post-monsoon seasons, which resulted in similar trends of both precipitation stable isotopes and temperature. The marine moisture was transported to the northern Hengduan Mountains by the winter India-Burma Trough combined with convection. Consequently, stable isotopes in subsequent precipitation were occasionally observed to decrease suddenly. However, δ18 O and δD values of precipitation at Qamdo were lower during the monsoon period and the duration of those low values was longer because of the effects of the Indian Summer Monsoon and the strengthening convection. Our findings indicate that the effects of seasonal precipitation differences caused by various climate systems, including the winter India-Burma Trough and Indian Summer Monsoon, need to be considered when attempting to interpret tree-ring and ice core records for the Hengduan Mountains.

Modeling of water isotopes in polar regions and application to ice core studies

NASA Astrophysics Data System (ADS)

Jouzel, J.

2012-04-01

Willi Dansgaard spear-headed the use of the stable isotopes of water in climatology and palaeoclimatology especially as applied to deep ice cores for which measurements of the oxygen and hydrogen isotope ratios remain the key tools for reconstructing continuous palaeotemperature records. In the line of his pioneering work on "Stable isotopes in precipitation" published in Tellus in 1964, I will review how isotopic models, either Rayleigh type or based on the implementation of water isotopes in General Circulation Models, have developed and been used for applications in polar ice core studies. This will include a discussion of the conventional approach for interpreting water isotopes in ice cores and of additional information provided by measurements of the deuterium excess and more recently of the 17O-excess.

Quantifying N2O reduction to N2 based on N2O isotopocules - validation with independent methods (helium incubation and 15N gas flux method)

NASA Astrophysics Data System (ADS)

Lewicka-Szczebak, Dominika; Augustin, Jürgen; Giesemann, Anette; Well, Reinhard

2017-02-01

Stable isotopic analyses of soil-emitted N2O (δ15Nbulk, δ18O and δ15Nsp = 15N site preference within the linear N2O molecule) may help to quantify N2O reduction to N2, an important but rarely quantified process in the soil nitrogen cycle. The N2O residual fraction (remaining unreduced N2O, rN2O) can be theoretically calculated from the measured isotopic enrichment of the residual N2O. However, various N2O-producing pathways may also influence the N2O isotopic signatures, and hence complicate the application of this isotopic fractionation approach. Here this approach was tested based on laboratory soil incubations with two different soil types, applying two reference methods for quantification of rN2O: helium incubation with direct measurement of N2 flux and the 15N gas flux method. This allowed a comparison of the measured rN2O values with the ones calculated based on isotopic enrichment of residual N2O. The results indicate that the performance of the N2O isotopic fractionation approach is related to the accompanying N2O and N2 source processes and the most critical is the determination of the initial isotopic signature of N2O before reduction (δ0). We show that δ0 can be well determined experimentally if stable in time and then successfully applied for determination of rN2O based on δ15Nsp values. Much more problematic to deal with are temporal changes of δ0 values leading to failure of the approach based on δ15Nsp values only. For this case, we propose here a dual N2O isotopocule mapping approach, where calculations are based on the relation between δ18O and δ15Nsp values. This allows for the simultaneous estimation of the N2O-producing pathways' contribution and the rN2O value.

Isotopic niche partitioning between two apex predators over time.

PubMed

Drago, Massimiliano; Cardona, Luis; Franco-Trecu, Valentina; Crespo, Enrique A; Vales, Damián G; Borella, Florencia; Zenteno, Lisette; Gonzáles, Enrique M; Inchausti, Pablo

2017-07-01

Stable isotope analyses have become an important tool in reconstructing diets, analysing resource use patterns, elucidating trophic relations among predators and understanding the structure of food webs. Here, we use stable carbon and nitrogen isotope ratios in bone collagen to reconstruct and compare the isotopic niches of adult South American fur seals (Arctocephalus australis; n = 86) and sea lions (Otaria flavescens; n = 49) - two otariid species with marked morphological differences - in the Río de la Plata estuary (Argentina - Uruguay) and the adjacent Atlantic Ocean during the second half of the 20th century and the beginning of the 21st century. Samples from the middle Holocene (n = 7 fur seals and n = 5 sea lions) are also included in order to provide a reference point for characterizing resource partitioning before major anthropogenic modifications of the environment. We found that the South American fur seals and South American sea lions had distinct isotopic niches during the middle Holocene. Isotopic niche segregation was similar at the beginning of the second half of the 20th century, but has diminished over time. The progressive convergence of the isotopic niches of these two otariids during the second half of the 20th century and the beginning of the 21st century is most likely due to the increased reliance of South American fur seals on demersal prey. This recent dietary change in South American fur seals can be explained by at least two non-mutually exclusive mechanisms: (i) the decrease in the abundance of sympatric South American sea lions as a consequence of small colony size and high pup mortality resulting from commercial sealing; and (ii) the decrease in the average size of demersal fishes due to intense fishing of the larger class sizes, which may have increased their accessibility to those eared seals with a smaller mouth gape, that is, South American fur seals of both sexes and female South American sea lions. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Mass spectrometric measurement of hydrogen isotope fractionation for the reactions of chloromethane with OH and Cl

NASA Astrophysics Data System (ADS)

Keppler, Frank; Bahlmann, Enno; Greule, Markus; Schöler, Heinz Friedrich; Wittmer, Julian; Zetzsch, Cornelius

2018-05-01

Chloromethane (CH3Cl) is an important provider of chlorine to the stratosphere but detailed knowledge of its budget is missing. Stable isotope analysis is a potentially powerful tool to constrain CH3Cl flux estimates. The largest degree of isotope fractionation is expected to occur for deuterium in CH3Cl in the hydrogen abstraction reactions with its main sink reactant tropospheric OH and its minor sink reactant Cl atoms. We determined the isotope fractionation by stable hydrogen isotope analysis of the fraction of CH3Cl remaining after reaction with hydroxyl and chlorine radicals in a 3.5 m3 Teflon smog chamber at 293 ± 1 K. We measured the stable hydrogen isotope values of the unreacted CH3Cl using compound-specific thermal conversion isotope ratio mass spectrometry. The isotope fractionations of CH3Cl for the reactions with hydroxyl and chlorine radicals were found to be -264±45 and -280±11 ‰, respectively. For comparison, we performed similar experiments using methane (CH4) as the target compound with OH and obtained a fractionation constant of -205±6 ‰ which is in good agreement with values previously reported. The observed large kinetic isotope effects are helpful when employing isotopic analyses of CH3Cl in the atmosphere to improve our knowledge of its atmospheric budget.

SAIL--stereo-array isotope labeling.

PubMed

Kainosho, Masatsune; Güntert, Peter

2009-11-01

Optimal stereospecific and regiospecific labeling of proteins with stable isotopes enhances the nuclear magnetic resonance (NMR) method for the determination of the three-dimensional protein structures in solution. Stereo-array isotope labeling (SAIL) offers sharpened lines, spectral simplification without loss of information and the ability to rapidly collect and automatically evaluate the structural restraints required to solve a high-quality solution structure for proteins up to twice as large as before. This review gives an overview of stable isotope labeling methods for NMR spectroscopy with proteins and provides an in-depth treatment of the SAIL technology.

Membrane inlet laser spectroscopy to measure H and O stable isotope compositions of soil and sediment pore water with high sample throughput

DOE PAGES

Oerter, Erik J.; Perelet, Alexei; Pardyjak, Eric; ...

2016-10-20

Here, the fast and accurate measurement of H and O stable isotope compositions (δ 2H and δ 18O values) of soil and sediment pore water remains an impediment to scaling-up the application of these isotopes in soil and vadose hydrology. Here we describe a method and its calibration to measuring soil and sediment pore water δ 2H and δ 18O values using a water vapor-permeable probe coupled to an isotope ratio infrared spectroscopy analyzer.

Dolomitization in a mixing zone of near-seawater composition, Late Pleistocene, northeastern Yucatan Peninsula

USGS Publications Warehouse

Ward, W. C.; Halley, Robert B.

1985-01-01

18O compositions of Yucatecan dolomite and of modern ground water suggest dolomite precipitation from mixed water ranging from about 75% seawater, 25% freshwater to nearly all seawater. (Isotope analyses are for the most stable calcian dolomites; more soluble, calcium-rich dolomite presumably is analyzed with calcite and thought to be isotopically lighter than the less soluble dolomite.) In the cement sequence, the most stable dolomite is followed by more soluble dolomite as ground water becomes less saline. Isotope analyses, together with position of dolomite in the cement sequence, suggest the most stable calcian dolomite (including limpid dolomite) precipitated from mixed water with large proportions of seawater, and the less stable, more calcian dolomite precipitated from fresher mixed water.

Control of Origin of Sesame Oil from Various Countries by Stable Isotope Analysis and DNA Based Markers—A Pilot Study

PubMed Central

Horacek, Micha; Hansel-Hohl, Karin; Burg, Kornel; Soja, Gerhard; Okello-Anyanga, Walter; Fluch, Silvia

2015-01-01

The indication of origin of sesame seeds and sesame oil is one of the important factors influencing its price, as it is produced in many regions worldwide and certain provenances are especially sought after. We joined stable carbon and hydrogen isotope analysis with DNA based molecular marker analysis to study their combined potential for the discrimination of different origins of sesame seeds. For the stable carbon and hydrogen isotope data a positive correlation between both isotope parameters was observed, indicating a dominant combined influence of climate and water availability. This enabled discrimination between sesame samples from tropical and subtropical/moderate climatic provenances. Carbon isotope values also showed differences between oil from black and white sesame seeds from identical locations, indicating higher water use efficiency of plants producing black seeds. DNA based markers gave independent evidence for geographic variation as well as provided information on the genetic relatedness of the investigated samples. Depending on the differences in ambient environmental conditions and in the genotypic fingerprint, a combination of both analytical methods is a very powerful tool to assess the declared geographic origin. To our knowledge this is the first paper on food authenticity combining the stable isotope analysis of bio-elements with DNA based markers and their combined statistical analysis. PMID:25831054

Control of origin of sesame oil from various countries by stable isotope analysis and DNA based markers--a pilot study.

PubMed

Horacek, Micha; Hansel-Hohl, Karin; Burg, Kornel; Soja, Gerhard; Okello-Anyanga, Walter; Fluch, Silvia

2015-01-01

The indication of origin of sesame seeds and sesame oil is one of the important factors influencing its price, as it is produced in many regions worldwide and certain provenances are especially sought after. We joined stable carbon and hydrogen isotope analysis with DNA based molecular marker analysis to study their combined potential for the discrimination of different origins of sesame seeds. For the stable carbon and hydrogen isotope data a positive correlation between both isotope parameters was observed, indicating a dominant combined influence of climate and water availability. This enabled discrimination between sesame samples from tropical and subtropical/moderate climatic provenances. Carbon isotope values also showed differences between oil from black and white sesame seeds from identical locations, indicating higher water use efficiency of plants producing black seeds. DNA based markers gave independent evidence for geographic variation as well as provided information on the genetic relatedness of the investigated samples. Depending on the differences in ambient environmental conditions and in the genotypic fingerprint, a combination of both analytical methods is a very powerful tool to assess the declared geographic origin. To our knowledge this is the first paper on food authenticity combining the stable isotope analysis of bio-elements with DNA based markers and their combined statistical analysis.

Nucleosynthetic Heterogeneity Controls Vanadium Isotope Variations in Bulk Chondrites

NASA Technical Reports Server (NTRS)

Nielsen, S. G.; Righter, K.; Wu, F.; Owens, J. D.; Prytulak, J.; Burton, K.; Parkinson, I.; Davis, D.

2018-01-01

The vanadium (V) isotope composition of early solar system materials have been hypothesized to be sensitive to high energy irradiation that originated from the young Sun. Vanadium has two isotopes with masses 50 and 51 that have (51)V/(50)V ratio of approximately 410. High energy irradiation produces (50)V from various target isotopes of Ti, Cr and Fe, which would result in light V isotope compositions (expressed as delta (51)V in per mille = 1000 x (((51)V/(50)V(sub sample)/(51)V/(50)V(sub AlfaAesar)) - 1)) relative to a presumably chondritic starting composition. Recently published V isotope data for calcium aluminium inclusions (CAIs) has revealed some very negative values relative to chondrites (by almost -4 per mille) that were indeed interpreted to reflect irradiation processes despite the fact that the studied CAIs all exhibited significant initial abundances of (10)Be, while only a few CAIs displayed light V isotope compositions. It is difficult to relate V isotope variations directly to a singular process because V only possesses two isotopes. Therefore, V isotope variations can principally be produced both mass dependent and independent processes. Mass dependent kinetic stable isotope fractionation is common in CAIs for refractory elements due to partial condensation/evaporation processes. The element strontium (Sr) has an almost identical condensation temperature to V and studies of stable Sr isotope compositions in CAIs reveal both heavy and light values relative to chondrites of several permil. These variations are similar in magnitude to those reported for V isotopes in CAIs, which suggests it is possible that some of the V isotope variation in CAIs could be due to kinetic stable isotope fractionation during condensation/evaporation processes.

MixSIAR: advanced stable isotope mixing models in R

EPA Science Inventory

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

Water quality conditions and food web structure in Chequamegon Bay

EPA Science Inventory

Abstract: Stable isotopes of carbon and nitrogen are powerful tools for tracing human- and watershed-derived nutrients and energy in coastal ecosystems. We used carbon and nitrogen stable isotope analysis to identify externally- and internally-produced nutrients and energy suppor...

Development of stable isotope mixing models in ecology - Dublin

EPA Science Inventory

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

Historical development of stable isotope mixing models in ecology

EPA Science Inventory

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

Development of stable isotope mixing models in ecology - Perth

EPA Science Inventory

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

Development of stable isotope mixing models in ecology - Fremantle

EPA Science Inventory

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

Development of stable isotope mixing models in ecology - Sydney

EPA Science Inventory

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

Modelingofwaterisotopesinpolarregionsandapplicationtoicecorestudies

NASA Astrophysics Data System (ADS)

Jouzel, J.

2012-04-01

Willi Dansgaard spear-headed the use of the stable isotopes of water in climatology and palaeoclimatology especially as applied to deep ice cores for which measurements of the oxygen and hydrogen isotope ratios remain the key tools for reconstructing continuous palaeotemperature records. In the line of his pioneering work on "Stable isotopes in precipitation" published in Tellus in 1964, I will review how isotopic models, either Rayleigh type or based on the implementation of water isotopes in General Circulation Models, have developed and been used for applications in polar ice core studies. This will include a discussion of the conventional approach for interpreting water isotopes in ice cores and of additional information provided by measurements of the deuterium excess and more recently of the 17O-excess.

Reconstruction of an aquatic food web: Viking Haithabu vs. Medieval Schleswig.

PubMed

von Steinsdorff, Katja; Grupe, Gisela

2006-09-01

In the last two decades, the analysis of stable isotopes of carbonate and collagen from archaeological bone finds became a useful tool in the reconstruction of ancient food webs. Nevertheless there is still only little information available about aquatic food webs, in particular concerning brackish water ecosystems. The Schlei Fjord in Schleswig-Holstein, Germany, is such an ecosystem and was investigated to determine stable isotopic values for nitrogen, carbon and oxygen from bone collagen and carbonate in archaeological bone finds. Wild birds, mammals and fish bones from the Viking settlement Haithabu and the medieval town of Schleswig have been analyzed in this study to determine stable isotope values for marine and limnic species and to investigate possible isotopic gradients for mixing fresh water and salt water ecosystems.

Development and co-validation of porcine insulin certified reference material by high-performance liquid chromatography-isotope dilution mass spectrometry.

PubMed

Wu, Liqing; Takatsu, Akiko; Park, Sang-Ryoul; Yang, Bin; Yang, Huaxin; Kinumi, Tomoya; Wang, Jing; Bi, Jiaming; Wang, Yang

2015-04-01

This article concerns the development and co-validation of a porcine insulin (pINS) certified reference material (CRM) produced by the National Institute of Metrology, People's Republic of China. Each CRM unit contained about 15 mg of purified solid pINS. The moisture content, amount of ignition residue, molecular mass, and purity of the pINS were measured. Both high-performance liquid chromatography-isotope dilution mass spectrometry and a purity deduction method were used to determine the mass fraction of the pINS. Fifteen units were selected to study the between-bottle homogeneity, and no inhomogeneity was observed. A stability study concluded that the CRM was stable for at least 12 months at -20 °C. The certified value of the CRM was (0.892 ± 0.036) g/g. A co-validation of the CRM was performed among Chinese, Japanese, and Korean laboratories under the framework of the Asian Collaboration on Reference Materials. The co-validation results agreed well with the certified value of the CRM. Consequently, the pINS CRM may be used as a calibration material or as a validation standard for pharmaceutical purposes to improve the quality of pharmaceutical products.

Calcium Isotopes in Foraminifera Shells: Evaluation for Paleo-temperature Reconstruction

NASA Astrophysics Data System (ADS)

Paytan, A.; Revello, C. A.; Bullen, T. D.

2002-12-01

The Ca stable isotope ratio of foraminifera shells has been suggested as a potential paleo-temperature proxy and has recently been applied in several studies to reconstruct glacial interglacial fluctuations in seawater temperatures. The major advantage of using Ca isotopes for paleo-temperature reconstruction is the relatively long residence time of Ca in the ocean. Thus, no spatial or temporal change in the Ca isotopic composition of seawater is expected over time scales much shorter than a million years. Moreover, since Ca is a major constituent of carbonate, and an isotopic ratio rather than an element concentration or element-element ratio (e.g. Mg/Ca, Sr/Ca) is measured, the Ca isotope proxy is much less likely to be affected by post depositional diagenetic alteration. However, preliminary results indicate that kinetic effects might largely control the Ca isotope fractionation involved in calcite shell formation. Before this new and exciting proxy can be utilized routinely, a better understanding of the parameters controlling Ca isotope fractionation in carbonate minerals in general and in foraminifera and other carbonate-secreting organisms is required. We have measured the Ca stable isotope ratio of several foraminifera species from core top sediments from two well-studied sites to determine the inter-species and within-species variability in Ca isotopes. We assess the effects of water temperature, calcification rate, and vital effects on the Ca stable isotope ratio of modern foraminifera and evaluate the potential of this proxy for paleo-temperature reconstruction.

Effect of trans-reservoir water supply on carbon and nitrogen stable isotope composition in hydrologically connected reservoirs in China

NASA Astrophysics Data System (ADS)

Zhang, Huajun; Peng, Liang; Gu, Binhe; Han, Bo-Ping

2017-09-01

Dajingshan, Fenghuangshan and Meixi reservoirs are located in Zhuhai, a coastal city in southern China, and they function to supply drinking water to Zhuhai and Macau. For effectively supplying waster, they are hydrologically connected and Dajingshan Reservoir first receives the water pumped from the river at Guangchang Pumping Station, and then feeds Fenghuangshan Reservoir, and the two well-connected reservoirs are mesotrophic. Meixi Reservoir is a small and oligotrophic water body and feeds Dajingshan Reservoir only in wet seasons when overflow occurs. Particulate organic matter (POM) was collected from three hydrologically connected water supply reservoirs, and seasonal variations of POM were ascertained from stable carbon and nitrogen isotopes in wet and dry seasons, and the effects of pumping water and reservoir connectivity on POM variations and composition were demonstrated by the relationships of the stable isotope ratios of POM. Seasonality and similarity of stable carbon and nitrogen isotopes of POM varied with hydrodynamics, connectivity and trophic states of the four studied water bodies. The two well-connected reservoirs displayed more similar seasonality for δ13CPOM than those between the river station and the two reservoirs. However, the opposite seasonality appeared for δ15NPOM between the above waters and indicates different processes affecting the stable carbon and nitrogen isotopes of POM. δ13CPOM and δ15NPOM changed little between wet and dry seasons in Meixi Reservoir-a low productive and rain-driven system, suggesting little POM response to environmental changes in that water system. As expected, connectivity enhanced the similarity of the stable isotope ratios of POM between the water bodies.

Selecting the best stable isotope mixing model to estimate grizzly bear diets in the Greater Yellowstone Ecosystem

PubMed Central

Hopkins, John B.; Ferguson, Jake M.; Tyers, Daniel B.; Kurle, Carolyn M.

2017-01-01

Past research indicates that whitebark pine seeds are a critical food source for Threatened grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE). In recent decades, whitebark pine forests have declined markedly due to pine beetle infestation, invasive blister rust, and landscape-level fires. To date, no study has reliably estimated the contribution of whitebark pine seeds to the diets of grizzlies through time. We used stable isotope ratios (expressed as δ13C, δ15N, and δ34S values) measured in grizzly bear hair and their major food sources to estimate the diets of grizzlies sampled in Cooke City Basin, Montana. We found that stable isotope mixing models that included different combinations of stable isotope values for bears and their foods generated similar proportional dietary contributions. Estimates generated by our top model suggest that whitebark pine seeds (35±10%) and other plant foods (56±10%) were more important than meat (9±8%) to grizzly bears sampled in the study area. Stable isotope values measured in bear hair collected elsewhere in the GYE and North America support our conclusions about plant-based foraging. We recommend that researchers consider model selection when estimating the diets of animals using stable isotope mixing models. We also urge researchers to use the new statistical framework described here to estimate the dietary responses of grizzlies to declines in whitebark pine seeds and other important food sources through time in the GYE (e.g., cutthroat trout), as such information could be useful in predicting how the population will adapt to future environmental change. PMID:28493929

Selecting the best stable isotope mixing model to estimate grizzly bear diets in the Greater Yellowstone Ecosystem.

PubMed

Hopkins, John B; Ferguson, Jake M; Tyers, Daniel B; Kurle, Carolyn M

2017-01-01

Past research indicates that whitebark pine seeds are a critical food source for Threatened grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE). In recent decades, whitebark pine forests have declined markedly due to pine beetle infestation, invasive blister rust, and landscape-level fires. To date, no study has reliably estimated the contribution of whitebark pine seeds to the diets of grizzlies through time. We used stable isotope ratios (expressed as δ13C, δ15N, and δ34S values) measured in grizzly bear hair and their major food sources to estimate the diets of grizzlies sampled in Cooke City Basin, Montana. We found that stable isotope mixing models that included different combinations of stable isotope values for bears and their foods generated similar proportional dietary contributions. Estimates generated by our top model suggest that whitebark pine seeds (35±10%) and other plant foods (56±10%) were more important than meat (9±8%) to grizzly bears sampled in the study area. Stable isotope values measured in bear hair collected elsewhere in the GYE and North America support our conclusions about plant-based foraging. We recommend that researchers consider model selection when estimating the diets of animals using stable isotope mixing models. We also urge researchers to use the new statistical framework described here to estimate the dietary responses of grizzlies to declines in whitebark pine seeds and other important food sources through time in the GYE (e.g., cutthroat trout), as such information could be useful in predicting how the population will adapt to future environmental change.

Comparative isotope ecology of African great apes.

PubMed

Oelze, Vicky M; Fahy, Geraldine; Hohmann, Gottfried; Robbins, Martha M; Leinert, Vera; Lee, Kevin; Eshuis, Henk; Seiler, Nicole; Wessling, Erin G; Head, Josephine; Boesch, Christophe; Kühl, Hjalmar S

2016-12-01

The isotope ecology of great apes is a useful reference for palaeodietary reconstructions in fossil hominins. As extant apes live in C 3 -dominated habitats, variation in isotope signatures is assumed to be low compared to hominoids exploiting C 4 -plant resources. However, isotopic differences between sites and between and within individuals are poorly understood due to the lack of vegetation baseline data. In this comparative study, we included all species of free-ranging African great apes (Pan troglodytes, Pan paniscus, Gorilla sp.). First, we explore differences in isotope baselines across different habitats and whether isotopic signatures in apes can be related to feeding niches (faunivory and folivory). Secondly, we illustrate how stable isotopic variations within African ape populations compare to other extant and extinct primates and discuss possible implications for dietary flexibility. Using 701 carbon and nitrogen isotope data points resulting from 148 sectioned hair samples and an additional collection of 189 fruit samples, we compare six different great ape sites. We investigate the relationship between vegetation baselines and climatic variables, and subsequently correct great ape isotope data to a standardized plant baseline from the respective sites. We obtained temporal isotopic profiles of individual animals by sectioning hair along its growth trajectory. Isotopic signatures of great apes differed between sites, mainly as vegetation isotope baselines were correlated with site-specific climatic conditions. We show that controlling for plant isotopic characteristics at a given site is essential for faunal data interpretation. While accounting for plant baseline effects, we found distinct isotopic profiles for each great ape population. Based on evidence from habituated groups and sympatric great ape species, these differences could possibly be related to faunivory and folivory. Dietary flexibility in apes varied, but temporal variation was overall lower than in fossil hominins and extant baboons, shifting from C 3 to C 4 -resources, providing new perspectives on comparisons between extinct and extant primates. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mercury contamination and stable isotopes reveal variability in foraging ecology of generalist California gulls

USGS Publications Warehouse

Peterson, Sarah; Ackerman, Joshua T.; Eagles-Smith, Collin A.

2017-01-01

Environmental contaminants are a concern for animal health, but contaminant exposure can also be used as a tracer of foraging ecology. In particular, mercury (Hg) concentrations are highly variable among aquatic and terrestrial food webs as a result of habitat- and site-specific biogeochemical processes that produce the bioaccumulative form, methylmercury (MeHg). We used stable isotopes and total Hg (THg) concentrations of a generalist consumer, the California gull (Larus californicus), to examine foraging ecology and illustrate the utility of using Hg contamination as an ecological tracer under certain conditions. We identified four main foraging clusters of gulls during pre-breeding and breeding, using a traditional approach based on light stable isotopes. The foraging cluster with the highest δ15N and δ34S values in gulls (cluster 4) had mean blood THg concentrations 614% (pre-breeding) and 250% (breeding) higher than gulls with the lowest isotope values (cluster 1). Using a traditional approach of stable-isotope mixing models, we showed that breeding birds with a higher proportion of garbage in their diet (cluster 2: 63–82% garbage) corresponded to lower THg concentrations and lower δ15N and δ34S values. In contrast, gull clusters with higher THg concentrations, which were more enriched in 15N and 34S isotopes, consumed a higher proportion of more natural, estuarine prey. δ34S values, which change markedly across the terrestrial to marine habitat gradient, were positively correlated with blood THg concentrations in gulls. The linkage we observed between stable isotopes and THg concentrations suggests that Hg contamination can be used as an additional tool for understanding animal foraging across coastal habitat gradients.

Seasonal and ENSO Influences on the Stable Isotopic Composition of Galápagos Precipitation

NASA Astrophysics Data System (ADS)

Martin, N. J.; Conroy, J. L.; Noone, D.; Cobb, K. M.; Konecky, B. L.; Rea, S.

2018-01-01

The origin of stable isotopic variability in precipitation over time and space is critical to the interpretation of stable isotope-based paleoclimate proxies. In the eastern equatorial Pacific, modern stable isotope measurements in precipitation (δ18Op and δDp) are sparse and largely unevaluated in the literature, although insights from such analyses would benefit the interpretations of several regional isotope-based paleoclimate records. Here we present a new 3.5 year record of daily-resolved δ18Op and δDp from Santa Cruz, Galápagos. With a prior 13 year record of monthly δ18Op and δDp from the island, these new data reveal controls on the stable isotopic composition of regional precipitation on event to interannual time scales. Overall, we find Galápagos δ18Op is significantly correlated with precipitation amount on daily and monthly time scales. The majority of Galápagos rain events are drizzle, or garúa, derived from local marine boundary layer vapor, with corresponding high δ18Op values due to the local source and increased evaporation and equilibration of smaller drops with boundary layer vapor. On monthly time scales, only precipitation in very strong, warm season El Niño months has substantially lower δ18Op values, as the sea surface temperature threshold for deep convection (28°C) is only surpassed at these times. The 2015/2016 El Niño event did not produce strong precipitation or δ18Op anomalies due to the short period of warm SST anomalies, which did not extend into the peak of the warm season. Eastern Pacific proxy isotope records may be biased toward periods of high rainfall during strong to very strong El Niño events.

Stable Nd isotope variations in the inner Solar System: The effect of sulfide during differentiation?

NASA Astrophysics Data System (ADS)

McCoy-West, A.

2017-12-01

Radiogenic neodymium isotopes have been widely used in studies of planetary accretion to constrain the timescales of early planetary differention [1]. Whereas stable isotope varitaions potentially provide information on the the processes that occur during planet formation. Experimental work suggests that the Earth's core contains a significant proportion of sulfide [2], and recent experimental work shows that under reducing conditions sulfide can incorporate substantial quantities of refractory lithophile elements [including Nd; 3]. If planetary embroyos also contain sulfide-rich cores, Nd stable isotopes have the potential to trace this sulfide segregation event in highly reduced environments, because there is a significant contrast in bonding environment between sulfide and silicate, where heavy isotopes should be preferentially incorporated into high force-constant bonds involving REE3+ (i.e. the silicate mantle). Here we present 146Nd/144Nd data, obtained using a double spike TIMS technique, for a range of planetary bodies formed at variable oxidation states including samples from the Moon, Mars, the asteriod 4Vesta and the Angrite and Aubrite parent bodies. Analyses of chondritic meteorites and terrestrial igneous rocks indicate that the Earth has a Nd stable isotope composition that is indistinguishable from that of chondrites [4]. Eucrites and martian meteorites also have compositons within error of the chondritic average. Significantly more variabilty is observed in the low concentration lunar samples and diogienite meteorites with Δ146Nd = 0.16‰. Preliminary results suggest that the Nd stable isotope composition of oxidised planetary bodies are homogeneous and modifications are the result of subordinate magmatic processes. [1] Boyet & Carlson, Science 309, 576 (2005) [2] Labidi et al. Nature 501, 208 (2013); [3] Wohlers &Wood, Nature 520, 337 (2015); [4] McCoy-West et al. Goldschmidt Ab. 429 (2017).

Population variation in isotopic composition of shorebird feathers: Implications for determining molting grounds

USGS Publications Warehouse

Torres-Dowdall, J.; Farmer, A.H.; Bucher, E.H.; Rye, R.O.; Landis, G.

2009-01-01

Stable isotope analyses have revolutionized the study of migratory connectivity. However, as with all tools, their limitations must be understood in order to derive the maximum benefit of a particular application. The goal of this study was to evaluate the efficacy of stable isotopes of C, N, H, O and S for assigning known-origin feathers to the molting sites of migrant shorebird species wintering and breeding in Argentina. Specific objectives were to: 1) compare the efficacy of the technique for studying shorebird species with different migration patterns, life histories and habitat-use patterns; 2) evaluate the grouping of species with similar migration and habitat use patterns in a single analysis to potentially improve prediction accuracy; and 3) evaluate the potential gains in prediction accuracy that might be achieved from using multiple stable isotopes. The efficacy of stable isotope ratios to determine origin was found to vary with species. While one species (White-rumped Sandpiper, Calidris fuscicollis) had high levels of accuracy assigning samples to known origin (91% of samples correctly assigned), another (Collared Plover, Charadrius collaris) showed low levels of accuracy (52% of samples correctly assigned). Intra-individual variability may account for this difference in efficacy. The prediction model for three species with similar migration and habitat-use patterns performed poorly compared with the model for just one of the species (71% versus 91% of samples correctly assigned). Thus, combining multiple sympatric species may not improve model prediction accuracy. Increasing the number of stable isotopes in the analyses increased the accuracy of assigning shorebirds to their molting origin, but the best combination - involving a subset of all the isotopes analyzed - varied among species.

Bird migration and avian influenza: a comparison of hydrogen stable isotopes and satellite tracking methods

USGS Publications Warehouse

Bridge, Eli S.; Kelly, Jeffrey F.; Xiao, Xiangming; Takekawa, John Y.; Hill, Nichola J.; Yamage, Mat; Haque, Enam Ul; Islam, Mohammad Anwarul; Mundkur, Taej; Yavuz, Kiraz Erciyas; Leader, Paul; Leung, Connie Y.H.; Smith, Bena; Spragens, Kyle A.; Vandegrift, Kurt J.; Hosseini, Parviez R.; Saif, Samia; Mohsanin, Samiul; Mikolon, Andrea; Islam, Ausrafal; George, Acty; Sivananinthaperumal, Balachandran; Daszak, Peter; Newman, Scott H.

2014-01-01

Satellite-based tracking of migratory waterfowl is an important tool for understanding the potential role of wild birds in the long-distance transmission of highly pathogenic avian influenza. However, employing this technique on a continental scale is prohibitively expensive. This study explores the utility of stable isotope ratios in feathers in examining both the distances traveled by migratory birds and variation in migration behavior. We compared the satellite-derived movement data of 22 ducks from 8 species captured at wintering areas in Bangladesh, Turkey, and Hong Kong with deuterium ratios (δD) in the feathers of these and other individuals captured at the same locations. We derived likely molting locations from the satellite tracking data and generated expected isotope ratios based on an interpolated map of δD in rainwater. Although δD was correlated with the distance between wintering and molting locations, surprisingly, measured δD values were not correlated with either expected values or latitudes of molting sites. However, population-level parameters derived from the satellite-tracking data, such as mean distance between wintering and molting locations and variation in migration distance, were reflected by means and variation of the stable isotope values. Our findings call into question the relevance of the rainfall isotope map for Asia for linking feather isotopes to molting locations, and underscore the need for extensive ground truthing in the form of feather-based isoscapes. Nevertheless, stable isotopes from feathers could inform disease models by characterizing the degree to which regional breeding populations interact at common wintering locations. Feather isotopes also could aid in surveying wintering locations to determine where high-resolution tracking techniques (e.g. satellite tracking) could most effectively be employed. Moreover, intrinsic markers such as stable isotopes offer the only means of inferring movement information from birds that have died as a result of infection. In the absence of feather based-isoscapes, we recommend a combination of isotope analysis and satellite-tracking as the best means of generating aggregate movement data for informing disease models.

Stable isotopic comparison between loggerhead sea turtle tissues.

PubMed

Vander Zanden, Hannah B; Tucker, Anton D; Bolten, Alan B; Reich, Kimberly J; Bjorndal, Karen A

2014-10-15

Stable isotope analysis has been used extensively to provide ecological information about diet and foraging location of many species. The difference in isotopic composition between animal tissue and its diet, or the diet-tissue discrimination factor, varies with tissue type. Therefore, direct comparisons between isotopic values of tissues are inaccurate without an appropriate conversion factor. We focus on the loggerhead sea turtle (Caretta caretta), for which a variety of tissues have been used to examine diet, habitat use, and migratory origin through stable isotope analysis. We calculated tissue-to-tissue conversions between two commonly sampled tissues. Epidermis and scute (the keratin covering on the carapace) were sampled from 33 adult loggerheads nesting at two beaches in Florida (Casey Key and Canaveral National Seashore). Carbon and nitrogen stable isotope ratios were measured in the epidermis and the youngest portion of the scute tissue, which reflect the isotopic composition of the diet and habitat over similar time periods of the order of several months. Significant linear relationships were observed between the δ(13)C and δ(15)N values of these two tissues, indicating they can be converted reliably. Whereas both epidermis and scute samples are commonly sampled from nesting sea turtles to study trophic ecology and habitat use, the data from these studies have not been comparable without reliable tissue-to-tissue conversions. The equations provided here allow isotopic datasets using the two tissues to be combined in previously published and subsequent studies of sea turtle foraging ecology and migratory movement. In addition, we recommend that future isotopic comparisons between tissues of any organism utilize linear regressions to calculate tissue-to-tissue conversions. Copyright © 2014 John Wiley & Sons, Ltd.

Seabird satellite tracking validates the use of latitudinal isoscapes to depict predators' foraging areas in the Southern Ocean.

PubMed

Jaeger, Audrey; Lecomte, Vincent J; Weimerskirch, Henri; Richard, Pierre; Cherel, Yves

2010-12-15

Stable isotopes are increasingly being used to trace wildlife movements. A fundamental prerequisite of animal isotopic tracking is a good knowledge of spatial isotopic variations in the environment. Few accessible reference maps of the isotopic landscape ("isoscapes") are available for marine predators. Here, we validate for the first time an isotopic gradient for higher trophic levels by using a unique combination of a large number of satellite-tracks and subsequent blood plasma isotopic signatures from a wide-ranging oceanic predator. The plasma δ(13)C and δ(15)N values of wandering albatrosses (n = 45) were highly and positively correlated to the Southern Ocean latitudes at which the satellite-tracked individuals foraged. The well-defined latitudinal baseline carbon isoscapes in the Southern Ocean is thus reflected in the tissue of consumers, but with a positive shift due to the cumulative effect of a slight (13)C-enrichment at each trophic level. The data allowed us to estimate the carbon isotopic position of the main oceanic fronts in the area, and thus to delineate robust isoscapes of the main foraging zones for top predators. The plasma δ(13)C and δ(15)N values were positively and linearly correlated, thus suggesting that latitudinal isoscapes also occur for δ(15)N at the base of the food web in oceanic waters of the Southern Ocean. The combination of device deployments with sampling of relevant tissues for isotopic analysis appears to be a powerful tool for investigating consumers' isoscapes at various spatio-temporal scales. Copyright © 2010 John Wiley & Sons, Ltd.

Strontium stable isotope behaviour accompanying basalt weathering

NASA Astrophysics Data System (ADS)

Burton, K. W.; Parkinson, I. J.; Gíslason, S. G. R.

2016-12-01

The strontium (Sr) stable isotope composition of rivers is strongly controlled by the balance of carbonate to silicate weathering (Krabbenhöft et al. 2010; Pearce et al. 2015). However, rivers draining silicate catchments possess distinctly heavier Sr stable isotope values than their bedrock compositions, pointing to significant fractionation during weathering. Some have argued for preferential release of heavy Sr from primary phases during chemical weathering, others for the formation of secondary weathering minerals that incorporate light isotopes. This study presents high-precision double-spike Sr stable isotope data for soils, rivers, ground waters and estuarine waters from Iceland, reflecting both natural weathering and societal impacts on those environments. The bedrock in Iceland is dominantly basaltic, d88/86Sr ≈ +0.27, extending to lighter values for rhyolites. Geothermal waters range from basaltic Sr stable compositions to those akin to seawater. Soil pore waters reflect a balance of input from primary mineral weathering, precipitation and litter recycling and removal into secondary phases and vegetation. Rivers and ground waters possess a wide range of d88/86Sr compositions from +0.101 to +0.858. Elemental and isotope data indicate that this fractionation primarily results from the formation or dissolution of secondary zeolite (d88/86Sr ≈ +0.10), but also carbonate (d88/86Sr ≈ +0.22) and sometimes anhydrite (d88/86Sr ≈ -0.73), driving the residual waters to heavier or lighter values, respectively. Estuarine waters largely reflect mixing with seawater, but are also be affected by adsorption onto particulates, again driving water to heavy values. Overall, these data indicate that the stability and nature of secondary weathering phases, exerts a strong control on the Sr stable isotope composition of silicate rivers. [1] Krabbenhöft et al. (2010) Geochim. Cosmochim. Acta 74, 4097-4109. [2] Pearce et al. (2015) Geochim. Cosmochim. Acta 157, 125-146.

Analysis of stable isotope ratios (δ18O and δ2H) in precipitation of the Verde River watershed, Arizona 2003 through 2014

USGS Publications Warehouse

Beisner, Kimberly R.; Paretti, Nicholas V.; Tucci, Rachel S.

2016-04-25

Stable isotope delta values (δ18O and δ2H) of precipitation can vary with elevation, and quantification of the precipitation elevation gradient can be used to predict recharge elevation within a watershed. Precipitation samples were analyzed for stable isotope delta values between 2003 and 2014 from the Verde River watershed of north-central Arizona. Results indicate a significant decrease in summer isotopic values overtime at 3,100-, 4,100-, 6,100-, 7,100-, and 8,100-feet elevation. The updated local meteoric water line for the area is δ2H = 7.11 δ18O + 3.40. Equations to predict stable isotopic values based on elevation were updated from previous publications in Blasch and others (2006), Blasch and Bryson (2007), and Bryson and others (2007). New equations were separated for samples from the Camp Verde to Flagstaff transect and the Prescott to Chino Valley transect. For the Camp Verde to Flagstaff transect, the new equations for winter precipitation are δ18O = -0.0004z − 8.87 and δ2H = -0.0029z − 59.8 (where z represents elevation in feet) and the summer precipitation equations were not statistically significant. For the Prescott to Chino Valley transect, the new equations for summer precipitation are δ18O = -0.0005z − 3.22 and δ2H = -0.0022z − 27.9; the winter precipitation equations were not statistically significant and, notably, stable isotope values were similar across all elevations. Interpretation of elevation of recharge contributing to surface and groundwaters in the Verde River watershed using the updated equations for the Camp Verde to Flagstaff transect will give lower elevation values compared with interpretations presented in the previous studies. For waters in the Prescott and Chino Valley area, more information is needed to understand local controls on stable isotope values related to elevation.

Late Quaternary Environmental Changes Inferred from the stable Oxygen Isotope Composition of Aquatic Insects (Chironomidae: Diptera) and Stable Hydrogen Isotope Composition of bulk sediments from Idavain Lake, Southwest Alaska

NASA Astrophysics Data System (ADS)

Wang, Y.; Finney, B.; Wooller, M. J.

2007-12-01

Several techniques are available to examine the isotopic composition of historic lake waters, providing data that can subsequently be used to examine environmental changes. Recently-developed techniques are the stable oxygen isotope analysis of subfossil chironomid (Diptera: Chironomidae) head capsules (mostly chitin) preserved in lake sediments and stable hydrogen isotope analyses directly on bulk sediments. An advantage of using δ18O of chironomids is that the chitinous chironomid headcapsules preserve well in lake sediments, retaining the stable oxygen isotope signature of the lake in which they lived. An advantage of δD analyses of bulk sediments is that a sediment core can be analyzed relatively easily and when the %C (total organic carbon) and %H profiles correlate the data can be used to infer past δD changes of the organics in the sediments. We present results from these analyses of a lake sediment core from Idavain Lake (58°46'N, 155°57'W, 223m above sea level) in southwest Alaska in concert with other paleolimnological proxies, including δ15N, δ13C, LOI, magnetic susceptibility, organic content and opal concentrations for a better understanding of paleolimnological changes since deglaciation for the region. Our preliminilary result shows that downcore shifts of δ18O analyzed from chironomid head capsules coincide well with LOI and pollen changes. The δD of sediments and TOM showed large magnitude changes and reflected the relative lake level changes during the record. This study aim to test the correlation between stable isotope analyese on chiornomid head capsules, lake water, and bulk sediments. In the addition, our study will add to the relatively small database of paleoenvironmental reconstructions from terrestrial sites in Southwest Alaska.

Isotopic modeling of the sub-cloud evaporation effect in precipitation.

PubMed

Salamalikis, V; Argiriou, A A; Dotsika, E

2016-02-15

In dry and warm environments sub-cloud evaporation influences the falling raindrops modifying their final stable isotopic content. During their descent from the cloud base towards the ground surface, through the unsaturated atmosphere, hydrometeors are subjected to evaporation whereas the kinetic fractionation results to less depleted or enriched isotopic signatures compared to the initial isotopic composition of the raindrops at cloud base. Nowadays the development of Generalized Climate Models (GCMs) that include isotopic content calculation modules are of great interest for the isotopic tracing of the global hydrological cycle. Therefore the accurate description of the underlying processes affecting stable isotopic content can improve the performance of iso-GCMs. The aim of this study is to model the sub-cloud evaporation effect using a) mixing and b) numerical isotope evaporation models. The isotope-mixing evaporation model simulates the isotopic enrichment (difference between the ground and the cloud base isotopic composition of raindrops) in terms of raindrop size, ambient temperature and relative humidity (RH) at ground level. The isotopic enrichment (Δδ) varies linearly with the evaporated raindrops mass fraction of the raindrop resulting to higher values at drier atmospheres and for smaller raindrops. The relationship between Δδ and RH is described by a 'heat capacity' model providing high correlation coefficients for both isotopes (R(2)>80%) indicating that RH is an ideal indicator of the sub-cloud evaporation effect. Vertical distribution of stable isotopes in falling raindrops is also investigated using a numerical isotope-evaporation model. Temperature and humidity dependence of the vertical isotopic variation is clearly described by the numerical isotopic model showing an increase in the isotopic values with increasing temperature and decreasing RH. At an almost saturated atmosphere (RH=95%) sub-cloud evaporation is negligible and the isotopic composition hardly changes even at high temperatures while at drier and warm conditions the enrichment of (18)Ο reaches up to 20‰, depending on the raindrop size and the initial meteorological conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Direct separation of boron from Na- and Ca-rich matrices by sublimation for stable isotope measurement by MC-ICP-MS.

PubMed

Wang, Bo-Shian; You, Chen-Feng; Huang, Kuo-Fang; Wu, Shein-Fu; Aggarwal, Suresh Kumar; Chung, Chuan-Hsiung; Lin, Pei-Ying

2010-09-15

An improved technique for precise and accurate determination of boron isotopic composition in Na-rich natural waters (groundwater, seawater) and marine biogenic carbonates was developed. This study used a 'micro-sublimation' technique to separate B from natural sample matrices in place of the conventional ion-exchange extraction. By adjusting analyte to appropriate pH, quantitative recovery of boron can be achieved (>98%) and the B procedural blank is limited to <8 pg. An additional mass bias effect in MC-ICP-MS was observed which could not be improved via the standard-sample-standard bracketing or the 'pseudo internal' normalization by Li. Therefore a standard other than NBS SRM 951 was used to monitor plasma condition in order to maintain analytical accuracy. An isotope cross-calibration with results from TIMS shows that the space-charge mass bias on MC-ICP-MS can be successfully corrected using off-line mathematical manipulation. Several reference materials, including the seawater IAPSO and two groundwater standards IAEA-B-2 and IAEA-B-3, were used to validate this approach. We found that the delta(11)B of the reference coral JCp-1 was 24.22+/-0.28 per thousand, corresponding to seawater pH based on the coral delta(11)B-pH function. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Introducing AAA-MS, a rapid and sensitive method for amino acid analysis using isotope dilution and high-resolution mass spectrometry.

PubMed

Louwagie, Mathilde; Kieffer-Jaquinod, Sylvie; Dupierris, Véronique; Couté, Yohann; Bruley, Christophe; Garin, Jérôme; Dupuis, Alain; Jaquinod, Michel; Brun, Virginie

2012-07-06

Accurate quantification of pure peptides and proteins is essential for biotechnology, clinical chemistry, proteomics, and systems biology. The reference method to quantify peptides and proteins is amino acid analysis (AAA). This consists of an acidic hydrolysis followed by chromatographic separation and spectrophotometric detection of amino acids. Although widely used, this method displays some limitations, in particular the need for large amounts of starting material. Driven by the need to quantify isotope-dilution standards used for absolute quantitative proteomics, particularly stable isotope-labeled (SIL) peptides and PSAQ proteins, we developed a new AAA assay (AAA-MS). This method requires neither derivatization nor chromatographic separation of amino acids. It is based on rapid microwave-assisted acidic hydrolysis followed by high-resolution mass spectrometry analysis of amino acids. Quantification is performed by comparing MS signals from labeled amino acids (SIL peptide- and PSAQ-derived) with those of unlabeled amino acids originating from co-hydrolyzed NIST standard reference materials. For both SIL peptides and PSAQ standards, AAA-MS quantification results were consistent with classical AAA measurements. Compared to AAA assay, AAA-MS was much faster and was 100-fold more sensitive for peptide and protein quantification. Finally, thanks to the development of a labeled protein standard, we also extended AAA-MS analysis to the quantification of unlabeled proteins.

Stable isotope monitoring of ionic trapping of CO2 in deep brines

NASA Astrophysics Data System (ADS)

Myrttinen, A.; Barth, J. A. C.; Becker, V.; Blum, P.; Grathwohl, P.

2009-04-01

CO2 injection into a depleted gas-reservoir is used as a combined method for Enhanced Gas Recovery (EGR) and CO2 storage. In order to safeguard this process, monitoring the degree of dissolution and potential further precipitation and mineral interactions are a necessity. Here a method is introduced, in which stable isotope and geochemical data can be used as a monitoring technique to quantify ionic trapping of injected CO2. Isotope and geochemical data of dissolved inorganic carbon (DIC) can be used to distinguish between already present and to be injected inorganic carbon. Injected CO2, for instance, is formed during combustion of former plant material and is expected to have a different isotope ratio (δ13C value) than the baseline data of the aquifer. This is because combusted CO2 originates from organic material, such as coal and oil with a predominant C3 plant signature. Mixing the injected CO2 with groundwater is therefore expected to change the isotope, as well as the geochemical composition of the groundwater. Mass balance calculations with stable isotope ratios can serve to quantify ionic trapping of CO2 as DIC in groundwater. However, depending on the composition of the aquifer, weathering of carbonate or silicates may occur. Enhanced weathering processes due to CO2 injection can also further influence the isotopic composition. Such interactions between dissolved CO2 and minerals depend on the temperature and pressure regimes applied. Field data, as well as laboratory experiments are planned to quantify isotope ratios of dissolved inorganic carbon as well as oxygen isotope ratios of the water. These are indicative of geochemical processes before, during and after EGR. The isotope method should therefore provide a new tool to quantify the efficiency of ionic trapping under various temperatures and pressures. Keywords: Enhanced Gas Recovery, monitoring of CO2 dissolution, stable isotopes

COMBINING SOURCES IN STABLE ISOTOPE MIXING MODELS: ALTERNATIVE METHODS

EPA Science Inventory

Stable isotope mixing models are often used to quantify source contributions to a mixture. Examples include pollution source identification; trophic web studies; analysis of water sources for soils, plants, or water bodies; and many others. A common problem is having too many s...

STABLE CHLORINE ISOTOPIC COMPOSITIONS OF AROCLORS AND ARCLOR-CONTAMINATED SEDIMENT

EPA Science Inventory

An exploratory investigation was conducted to evaluate if stable chlorine isotopic ratios of polychlorinated biphenyls (PCBs) could be useful in studying the processes that determine their transport and fate in the environment. First, we determined the variability of 37Cl in the...

STABLE ISOTOPES AS INDICATORS OF SOIL WATER DYNAMICS IN WATERSHEDS

EPA Science Inventory

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

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

Evaluation of stable isotope fingerprinting techniques for the assessment of the predominant methanogenic pathways in anaerobic digesters.

PubMed

Nikolausz, M; Walter, R F H; Sträuber, H; Liebetrau, J; Schmidt, T; Kleinsteuber, S; Bratfisch, F; Günther, U; Richnow, H H

2013-03-01

Laboratory biogas reactors were operated under various conditions using maize silage, chicken manure, or distillers grains as substrate. In addition to the standard process parameters, the hydrogen and carbon stable isotopic composition of biogas was analyzed to estimate the predominant methanogenic pathways as a potential process control tool. The isotopic fingerprinting technique was evaluated by parallel analysis of mcrA genes and their transcripts to study the diversity and activity of methanogens. The dominant hydrogenotrophs were Methanomicrobiales, while aceticlastic methanogens were represented by Methanosaeta and Methanosarcina at low and high organic loading rates, respectively. Major changes in the relative abundance of mcrA transcripts were observed compared to the results obtained from DNA level. In agreement with the molecular results, the isotope data suggested the predominance of the hydrogenotrophic pathway in one reactor fed with chicken manure, while both pathways were important in the other reactors. Short-term changes in the isotopic composition were followed, and a significant change in isotope values was observed after feeding a reactor digesting maize silage. This ability of stable isotope fingerprinting to follow short-term activity changes shows potential for indicating process failures and makes it a promising technology for process control.

Isotopic incorporation rates for shark tissues from a long-term captive feeding study.

PubMed

Kim, Sora Lee; del Rio, Carlos Martínez; Casper, Dave; Koch, Paul L

2012-07-15

Stable isotope analysis has provided insight into the dietary and habitat patterns of many birds, mammals and teleost fish. A crucial biological parameter to interpret field stable isotope data is tissue incorporation rate, which has not been well studied in large ectotherms. We report the incorporation of carbon and nitrogen into the tissues of leopard sharks (Triakis semifasciata). Because sharks have relatively slow metabolic rates and are difficult to maintain in captivity, no long-term feeding study has been conducted until the point of isotopic steady state with a diet. We kept six leopard sharks in captivity for 1250 days, measured their growth, and serially sampled plasma, red blood cells and muscle for stable carbon and nitrogen isotope analysis. A single-compartment model with first-order kinetics adequately described the incorporation patterns of carbon and nitrogen isotopes for these three tissues. Both carbon and nitrogen were incorporated faster in plasma than in muscle and red blood cells. The rate of incorporation of carbon into muscle was similar to that predicted by an allometric equation relating isotopic incorporation rate to body mass that was developed previously for teleosts. In spite of their large size and unusual physiology, the rates of isotopic incorporation in sharks seem to follow the same patterns found in other aquatic ectotherms.

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

NASA Astrophysics Data System (ADS)

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

2013-11-01

Product origin is of great importance for consumers especially because its association in consumer's perception with food quality, freedom from disease or pollution. Stable isotope ratio analysis is a powerful technique in food authenticity and traceability control which has been introduced within the European wine industry to ensure authenticity of wine provenance and to detect adulteration. Isotopic ratios measurements have also been successfully to other food commodities like: fruit juices, honey and dairy foods. The δ18O and δ2H content in milk water reflects the isotope composition of the ground water drunk by animals. Seasonal effects are also very important: in summer, milk water contains higher δ18O and δ2H values due to the fresh plants that are ate by animals. Relative carbon stable isotope abundances in total milk reflect the isotopic composition of the diet fed to the dairy cows. In this study the hydrogen, oxygen and carbon isotopic composition of 15 milk samples coming from a unit placed in the mountains of Transylvania was investigated. The distribution of the obtained isotopic values was than discussed taking into account that all the animals were feed with the same type of forage and consumed water was taken from the same source.

Medical Isotope Program: O-18, C-13, and Xe-129 Final Report CRADA No. TC-2043-02

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scheibner, K. F.; Fought, J.

This was a collaborative effort between the University of California, Lawrence Livermore National Laboratory (LLNL) and Spectra Gases, Inc., to develop new and cheaper sources of Oxgyen-18 (O-18), Carbon-13 (C-13), and Xenon-129 (Xe-129), and to develop new applications of these stable medical isotopes in medicine resulting in a substantial increase in stable isotopes that are important to human health sciences.

High-resolution stable isotope signature of a land-falling atmospheric river in Southern Norway

NASA Astrophysics Data System (ADS)

Weng, Yongbiao; Sodemann, Harald

2017-04-01

Gathering observational evidence of the long-range moisture versus local source contributions remains a scientific challenge, but is critical for understanding how hydrological extremes develop. Moisture transport to the west coast of Norway is often connected to elongated meridional structures of high water vapour flux known as Atmospheric Rivers. It is still an open question how well moisture sources estimated by different numerical models for such events of long-range transport correspond with reality. In this study, we present high resolution stable isotope information collected during a land-falling Atmospheric River in Southern Norway during winter 2016, and analyse the data with the aim to differentiate between moisture source signatures and below-cloud processes affecting the stable isotope composition. The precipitation characterised by a pronounced warm front was sampled manually on a rooftop platform at a 10-20 minute interval during the 24h of the event and later measured by a laser spectrometer (Picarro L2140-i) in the lab for δ18O, δD, and d-excess. Simultaneously, the stable isotope composition of water vapor was continuously measured at high resolution. To that end, ambient air was continuously pumped from a nearby inlet at 25 m above the ground and measured by another laser spectrometer (Picarro L2130-i). Stable water isotope measurements were supplemented by detailed precipitation parameters from a laser disdrometer (OTT Parsivel2), Micro Rain Radar (MRR-2), Total Precipitation Sensor (TPS-3100), and a nearby weather station. Measurements show a signature of two depletion periods in the main stable isotope parameters that are not apparent in precipitation amount and atmospheric temperature measurements. The deuterium excess in rainfall responds differently, with first and increase and then a decrease during these depletion periods. We interpret this as a combined consequence of airmass change, cloud microphysics, and below-cloud effects. Moisture sources identified during the atmospheric river event show a clear transition that points to the need to constrain this kind of analysis by additional stable water isotope observations en route and upstream.

Non-traditional stable isotope behaviors in immiscible silica-melts in a mafic magma chamber.

PubMed

Zhu, Dan; Bao, Huiming; Liu, Yun

2015-12-01

Non-traditional stable isotopes have increasingly been applied to studies of igneous processes including planetary differentiation. Equilibrium isotope fractionation of these elements in silicates is expected to be negligible at magmatic temperatures (δ(57)Fe difference often less than 0.2 per mil). However, an increasing number of data has revealed a puzzling observation, e.g., the δ(57)Fe for silicic magmas ranges from 0‰ up to 0.6‰, with the most positive δ(57)Fe almost exclusively found in A-type granitoids. Several interpretations have been proposed by different research groups, but these have so far failed to explain some aspects of the observations. Here we propose a dynamic, diffusion-induced isotope fractionation model that assumes Si-melts are growing and ascending immiscibly in a Fe-rich bulk magma chamber. Our model offers predictions on the behavior of non-traditional stable isotope such as Fe, Mg, Si, and Li that are consistent with observations from many A-type granitoids, especially those associated with layered intrusions. Diffusion-induced isotope fractionation may be more commonly preserved in magmatic rocks than was originally predicted.

Tracking ENSO with tropical trees: Progress in stable isotope dendroclimatology

NASA Astrophysics Data System (ADS)

Evans, M. N.; Poussart, P. F.; Saleska, S. R.; Schrag, D. P.

2002-12-01

The terrestrial tropics remain an important gap in the growing proxy network used to characterize past ENSO behavior. Here we describe a strategy for development of proxy estimates of paleo-ENSO, via proxy rainfall estimates derived from stable isotope (δ18O) measurements made on tropical trees. The approach applies a new model of oxygen isotopic composition of alpha-cellulose (Roden et al., 2000), a rapid method for cellulose extraction from raw wood (Brendel et al., 2000), and continuous flow isotope ratio mass spectrometry (Brand, 1996) to develop proxy chronological, rainfall and growth rate estimates from tropical trees, even those lacking annual rings. The promise and pitfalls of the approach are illustrated in pilot datasets from the US, Costa Rica, Brazil, and Peru, which show isotopic cycles of 4-6 per mil, and interannual anomalies of up to 8 per mil. Together with the mature ENSO proxies (corals, extratropical tree-rings, varved sediments, and ice cores), replicated and well-dated stable isotope chronologies from tropical trees may eventually improve our understanding of ENSO history over the past several hundred years.

Diet-tissue discrimination factors and turnover of carbon and nitrogen stable isotopes in tissues of an adult predatory coral reef fish, Plectropomus leopardus.

PubMed

Matley, J K; Fisk, A T; Tobin, A J; Heupel, M R; Simpfendorfer, C A

2016-01-15

Stable isotope ratios (δ(13)C and δ(15)N values) provide a unique perspective into the ecology of animals because the isotope ratio values of consumers reflect the values in food. Despite the value of stable isotopes in ecological studies, the lack of species-specific experimentally derived diet-tissue discrimination factors (DTDFs) and turnover rates limits their application at a broad scale. Furthermore, most aquatic feeding experiments use temperate, fast-growing fish species and few have considered medium- to large-sized adults with low growth rates from tropical ecosystems. A controlled-diet stable isotope feeding trial was conducted over a 196-day period for the adult predatory reef fish leopard coralgrouper (Plectropomus leopardus). This study calculated δ(13)C and δ(15)N DTDFs and turnover rates in five tissues (liver, plasma, red blood cells (RBC), fin, and muscle) using a continuous flow isotope ratio mass spectrometer equipped with an elemental analyzer. In addition, the effect of chemical lipid extraction (LE) on stable isotope values was examined for each tissue. Turnover was mainly influenced by metabolism (as opposed to growth) with LE δ(15)N half-life values lowest in fin (37 days) and plasma (66 days), and highest in RBC (88 days) and muscle (126 days). The diet-tissue discrimination factors for δ(15)N values in all tissues (Δ(15)N: -0.15 to 1.84‰) were typically lower than commonly reported literature values. Lipid extraction altered both δ(15) N and δ(13)C values compared with untreated samples; however, for the δ(15)N values, the differences were small (mean δ(15)N(LE-Bulk) <0.46‰ in all tissues). This study informs future interpretation of stable isotope data for medium- to large-sized fish and demonstrates that DTDFs developed for temperate fish species, particularly for δ(15)N values, may not apply to tropical species. Sampling of muscle and/or RBC is recommended for a relatively long-term representation of feeding habits, while plasma and/or fin should be used for a more recent indication of diet. Copyright © 2015 John Wiley & Sons, Ltd.

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

NASA Astrophysics Data System (ADS)

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

2008-12-01

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

Automated simultaneous measurement of the δ(13) C and δ(2) H values of methane and the δ(13) C and δ(18) O values of carbon dioxide in flask air samples using a new multi cryo-trap/gas chromatography/isotope ratio mass spectrometry system.

PubMed

Brand, Willi A; Rothe, Michael; Sperlich, Peter; Strube, Martin; Wendeberg, Magnus

2016-07-15

The isotopic composition of greenhouse gases helps to constrain global budgets and to study sink and source processes. We present a new system for high-precision stable isotope measurements of carbon, hydrogen and oxygen in atmospheric methane and carbon dioxide. The design is intended for analyzing flask air samples from existing sampling programs without the need for extra sample air for methane analysis. CO2 and CH4 isotopes are measured simultaneously using two isotope ratio mass spectrometers, one for the analysis of δ(13) C and δ(18) O values and the second one for δ(2) H values. The inlet carousel delivers air from 16 sample positions (glass flasks 1-5 L and high-pressure cylinders). Three 10-port valves take aliquots from the sample stream. CH4 from 100-mL air aliquots is preconcentrated in 0.8-mL sample loops using a new cryo-trap system. A precisely calibrated working reference air is used in parallel with the sample according to the Principle of Identical Treatment. It takes about 36 hours for a fully calibrated analysis of a complete carousel including extractions of four working reference and one quality control reference air. Long-term precision values, as obtained from the quality control reference gas since 2012, account for 0.04 ‰ (δ(13) C values of CO2 ), 0.07 ‰ (δ(18) O values of CO2 ), 0.11 ‰ (δ(13) C values of CH4 ) and 1.0 ‰ (δ(2) H values of CH4 ). Within a single day, the system exhibits a typical methane δ(13) C standard deviation (1σ) of 0.06 ‰ for 10 repeated measurements. The system has been in routine operation at the MPI-BGC since 2012. Consistency of the data and compatibility with results from other laboratories at a high precision level are of utmost importance. A high sample throughput and reliability of operation are important achievements of the presented system to cope with the large number of air samples to be analyzed. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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).

Tracing Carbon Flow from Primary Production to a Gulf Coast Salt Marsh Consumer, the Seaside Sparrow (Ammodramus maritimus)

NASA Astrophysics Data System (ADS)

Johnson, J. J.; Polito, M. J.; Olin, J.

2016-02-01

Determining the relative contributions of primary producers to salt marsh food webs is fundamental to understanding how these systems are structured. Biomarkers such as bulk carbon isotopes (13C/12C) and fatty acids have become popular tracers of trophic dynamics, based on the principle that the composition of biomarkers in consumer tissues is a reflection of the composition of these same biomarkers in a consumer's diet. However, the use of bulk stable isotope and fatty acid analyses to assess carbon flow in food webs is often hampered by confounding factors such as isotopic fractionation and fatty acid modifications that can occur between trophic levels. In contrast, compound-specific stable isotope analysis of amino acids may offer a more precise tracking of carbon flow through complex food webs. This is because the isotopic values of essential amino acids in consumer tissues are assimilated largely unchanged from their primary sources at the base of the food web. The aim of this study was to test the consistency of three different methods (bulk carbon stable isotope, fatty acid and compound-specific stable isotope analyses) while examining the carbon source pool underlying the diet of a common marsh consumer, the seaside sparrow (A. maritimus). This comparison allows us to gain a better idea of the relative merits of these analytical methods and contribute to a clearer model of overall trophic dynamics in a salt marsh food web.

Patterns in Stable Isotope Values of Nitrogen and Carbon in ...

EPA Pesticide Factsheets

Stable isotope measurements of nitrogen and carbon (15N, 13ddC) are often used to characterize estuarine, nearshore, and open ocean ecosystems. Reliable information about the spatial distribution of base-level stable isotope values, often represented by primary producers, is critical to interpreting values in these ecosystems. While base-level isotope data are generally readily available for estuaries, nearshore coastal waters, and the open ocean, the continental shelf is less studied. To address this, and as a first step toward developing a surrogate for base-level isotopic signature in this region, we collected surface and deep water samples from the United States’ eastern continental shelf in the Western Atlantic Ocean, from the Gulf of Maine to Cape Hatteras, periodically between 2000 and 2013. During the study, particulate matter 15dN values ranged from 0.8 to 17.4‰, and 13dC values from −26.4 to −15.6‰over the region. We used spatial autocorrelation analysis and random forest modeling to examine the spatial trends and potential environmental drivers of the stable isotope values. We observed general trends toward lower values for both nitrogen and carbon isotopes at the seaward edge of the shelf. Conversely, higher 15dN and 13dC values were observed on the landward edge of the shelf, in particular in the southern portion of the sampling area. Across all sites, the magnitude of the difference between the 15dN of subsurface and surface particulate m

Pollen-based reconstruction of Holocene climate variability in the Eifel region evaluated with stable isotopes

NASA Astrophysics Data System (ADS)

Kühl, Norbert; Moschen, Robert; Wagner, Stefanie

2010-05-01

Pollen as well as stable isotopes have great potential as climate proxy data. While variability in these proxy data is frequently assumed to reflect climate variability, other factors than climate, including human impact and statistical noise, can often not be excluded as primary cause for the observed variability. Multiproxy studies offer the opportunity to test different drivers by providing different lines of evidence for environmental change such as climate variability and human impact. In this multiproxy study we use pollen and peat humification to evaluate to which extent stable oxygen and carbon isotope series from the peat bog "Dürres Maar" reflect human impact rather than climate variability. For times before strong anthropogenic vegetation change, isotope series from Dürres Maar were used to validate quantitative reconstructions based on pollen. Our study site is the kettle hole peat bog "Dürres Maar" in the Eifel low mountain range, Germany (450m asl), which grew 12m during the last 10,000 years. Pollen was analysed with a sum of at least 1000 terrestrial pollen grains throughout the profile to minimize statistical effects on the reconstructions. A recently developed probabilistic indicator taxa method ("pdf-method") was used for the quantitative climate estimates (January and July temperature) based on pollen. For isotope analysis, attention was given to use monospecific Sphagnum leaves whenever possible, reducing the potential of a species effect and any potential artefact that can originate from selective degradation of different morphological parts of Sphagnum plants (Moschen et al., 2009). Pollen at "Dürres Maar" reflect the variable and partly strong human impact on vegetation during the last 4000 years. Stable isotope time series were apparently not influenced by human impact at this site. This highlights the potential of stable isotope investigations from peat for climatic interpretation, because stable isotope series from lacustrine sediments might strongly react to anthropogenic deforestation, as carbon isotope time series from the adjacent Lake Holzmaar suggest. Reconstructions based on pollen with the pdf-method are robust to the human impact during the last 4000 years, but do not reproduce the fine scale climate variability that can be derived from the stable isotope series (Kühl et al., in press). In contrast, reconstructions on the basis of pollen data show relatively pronounced climate variability (here: January temperature) during the Mid-Holocene, which is known from many other European records. The oxygen isotope time series as available now indicate that at least some of the observed variability indeed reflects climate variability. However, stable carbon isotopes show little concordance. At this stage our results point in the direction that 1) the isotopic composition might reflect a shift in influencing factors during the Holocene, 2) climate trends can robustly be reconstructed with the pdf method and 3) fine scale climate variability can potentially be reconstructed using the pdf-method, given that climate sensitive taxa at their distribution limit are present. The latter two conclusions are of particular importance for the reconstruction of climatic trends and variability of interglacials older than the Holocene, when sites are rare and pollen is often the only suitable proxy in terrestrial records. Kühl, N., Moschen, R., Wagner, S., Brewer, S., Peyron, O., in press. A multiproxy record of Late Holocene natural and anthropogenic environmental change from the Sphagnum peat bog Dürres Maar, Germany: implications for quantitative climate reconstructions based on pollen. J. Quat. Sci., DOI: 10.1002/jqs.1342. Available online. Moschen, R., Kühl, N., Rehberger, I., Lücke, A., 2009. Stable carbon and oxygen isotopes in sub-fossil Sphagnum: Assessment of their applicability for palaeoclimatology. Chemical Geology 259, 262-272.

Stable Vanadium Isotopes as a Redox Proxy at High Temperatures?

NASA Astrophysics Data System (ADS)

Prytulak, J.; Sossi, P.; Halliday, A.; Plank, T. A.; Savage, P.; Woodhead, J. D.

2016-12-01

There is currently no consensus on the relative oxygen fugacity (fO2) of the mantle source of mid-ocean ridge basalts compared to the sub-arc mantle, the region that is central to the mediation of crust-mantle mass balances. Vanadium is a multivalent transition metal whose stable isotope fractionation may reflect oxygen fugacity (fO2). However, a direct link between V isotope composition and fO2 is currently far from convincingly demonstrated. Furthermore, differences in co-ordination environment also play a large role in causing stable isotope fractionation. Here we present V isotope measurements of two suites of co-genetic magmas from contrasting tectonic settings: the Mariana arc and Hekla volcano, Iceland. We use this data alongside the tightly constrained V isotope composition of MORB [1] to assess the effects of fO2 and crystal fractionation on stable vanadium isotopes. We show that, for a given MgO content, V isotopes are identical within analytical error between arc basalts from the Marianas, lavas from Hekla, and MORB. The most striking aspect of our igneous, high temperature V isotope data is the large isotope fractionation (on the order of 2 ‰) towards heavier values in magmatic suites from both Hekla and the Marianas with progressive differentiation. We use a self consistent model of fractionating cotectic phases in both igneous suites to match major, trace and V isotope data. Vanadium partition coefficients required for (titano)magnetite are significantly higher in Hekla (DVmag = 42) than Mariana lavas (DVmag = 32), consistent with a more oxidised source in the latter. Calculated Rayleigh fractionation factors are similar in both suites (Δ51Vmin-melt of -0.4 to -0.5‰) and strongly implicate co-ordination differences between oxides and melt are the dominant driving force for V isotope fractionation. Thus, although fO2likely has a second order effect on V isotopes, they are not a direct proxy for oxygen fugacity in magmatic systems. [1] Prytulak, et al. 2013. EPSL 365, 177-189

Isotopic Analysis of Fingernails as a USGS Open House Demonstration of the Use of Stable Isotopes in Foodweb Studies

NASA Astrophysics Data System (ADS)

Silva, S. R.; Kendall, C.; Young, M. B.; Choy, D.

2011-12-01

The USGS Isotope Tracers Project uses stable isotopes and tritium to add a unique dimension of chemical information to a wide range of environmental investigations. The use and application of isotopes is usually an unfamiliar and even esoteric topic to the general public. Therefore during three USGS open house events, as a public outreach effort, we demonstrated the use of stable isotopes by analyzing nitrogen and carbon isotopes from very small fragments of fingernail from willing participants. We titled the exhibit "You Are What You Eat". The results from all participants were plotted on a graph indicating the general influence of different food groups on the composition of body tissues as represented by fingernails. All participants were assigned a number and no personal-identification information was collected. A subset of participants provided us with an estimate of the number of days a week various foods were eaten and if they were vegetarians, vegans or non-vegetarians. Volunteers from our research group were on hand to explain and discuss fundamental concepts such as how foods attain their isotopic composition, the difference between C3 and C4 plants, the effects of assimilation, trophic enrichment, and the various uses of stable isotopes in environmental studies. The results of the fingernail analyses showed the variation of the range of isotopic compositions among about 400 people at each event, the distinct influence of C4 plants (mainly corn and cane sugar) on our carbon isotopic composition, and the isotopic differences between vegetarians and non vegetarians among other details (http://wwwrcamnl.wr.usgs.gov/isoig/projects/fingernails/). A poll of visitors attending the open house event in 2006 indicated that "You Are What You Eat" was among the most popular exhibits. Following the first two open house events we were contacted by a group of researchers from Brazil who had completed a very similar study. Our collaboration resulted in a publication in the American Journal of Physical Anthropology (Nardoto et al., 2006). This study found that despite global trends toward dietary homogenization, regional differences in food resources and dietary preferences were recorded in the carbon and nitrogen isotopic compositions of fingernails.

Exploring water cycle dynamics by sampling multiple stable water isotope pools in a developed landscape in Germany

NASA Astrophysics Data System (ADS)

Orlowski, Natalie; Kraft, Philipp; Pferdmenges, Jakob; Breuer, Lutz

2016-09-01

A dual stable water isotope (δ2H and δ18O) study was conducted in the developed (managed) landscape of the Schwingbach catchment (Germany). The 2-year weekly to biweekly measurements of precipitation, stream, and groundwater isotopes revealed that surface and groundwater are isotopically disconnected from the annual precipitation cycle but showed bidirectional interactions between each other. Apparently, snowmelt played a fundamental role for groundwater recharge explaining the observed differences to precipitation δ values. A spatially distributed snapshot sampling of soil water isotopes at two soil depths at 52 sampling points across different land uses (arable land, forest, and grassland) revealed that topsoil isotopic signatures were similar to the precipitation input signal. Preferential water flow paths occurred under forested soils, explaining the isotopic similarities between top- and subsoil isotopic signatures. Due to human-impacted agricultural land use (tilling and compression) of arable and grassland soils, water delivery to the deeper soil layers was reduced, resulting in significant different isotopic signatures. However, the land use influence became less pronounced with depth and soil water approached groundwater δ values. Seasonally tracing stable water isotopes through soil profiles showed that the influence of new percolating soil water decreased with depth as no remarkable seasonality in soil isotopic signatures was obvious at depths > 0.9 m and constant values were observed through space and time. Since classic isotope evaluation methods such as transfer-function-based mean transit time calculations did not provide a good fit between the observed and calculated data, we established a hydrological model to estimate spatially distributed groundwater ages and flow directions within the Vollnkirchener Bach subcatchment. Our model revealed that complex age dynamics exist within the subcatchment and that much of the runoff must has been stored for much longer than event water (average water age is 16 years). Tracing stable water isotopes through the water cycle in combination with our hydrological model was valuable for determining interactions between different water cycle components and unravelling age dynamics within the study area. This knowledge can further improve catchment-specific process understanding of developed, human-impacted landscapes.

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

PubMed

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

2014-12-16

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

Grasland Stable Isotope Flux Measurements: Three Isotopomers of Carbon Dioxide Measured by QCL Spectroscopy

NASA Astrophysics Data System (ADS)

Zeeman, M. J.; Tuzson, B.; Eugster, W.; Werner, R. A.; Buchmann, N.; Emmenegger, L.

2007-12-01

To improve our understanding of greenhouse gas dynamics of managed ecosystems such as grasslands, we not only need to investigate the effects of management (e.g., grass cuts) and weather events (e.g., rainy days) on carbon dioxide fluxes, but also need to increase the time resolution of our measurements. Thus, for the first time, we assessed respiration and assimilation fluxes with high time resolution (5Hz) stable isotope measurements at an intensively managed farmland in Switzerland (Chamau, 400m ASL). Two different methods were used to quantify fluxes of carbon dioxide and associated fluxes of stable carbon isotopes: (1) the flux gradient method, and (2) the eddy covariance method. During a week long intensive measurement campaign, we (1) measured mixing ratios of carbon dioxide isotopomers (12C16O2, 12C16O18O, 13C16O2) with a Quantum Cascade Laser (QCL, Aerodyne Inc.) spectroscope and (2) collected air samples for isotope analyses (13C/12C) and (18O/16O) of carbon dioxide by Isotope Ratio Mass Spectrometry (IRMS, Finnigan) every two hours, concurrently along a height profile (z = 0.05; 0.10; 0.31; 2.15m). In the following week, the QCL setup was used for closed-path eddy covariance flux measurement of the carbon dioxide isotopomers, with the air inlet located next to an open-path Infra Red Gas Analyzers (IRGA, LiCor 7500) used simultaneously for carbon dioxide measurements. During this second week, an area of grass inside the footprint was cut and harvested after several days. The first results of in-field continuous QCL measurements of carbon dioxide mixing ratios and their stable isotopic ratios show good agreement with IRGA measurements and isotope analysis of flask samples by IRMS. Thus, QCL spectroscopy is a very promising tool for stable isotope flux investigations.

USING WINTER FLOUNDER GROWTH RATES AND STABLE ISOTOPES TO ASSESS HABITAT QUALITY

EPA Science Inventory

We used winter flounder growth rates and stable isotopes to assess habitat quality across an anthropogenic gradient in Narragansett Bay, Rhode Island. Cages (1 m2) were placed in the Providence River which had the highest nutrient concentrations and greatest development, Prudence...

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...

Using Stable Isotopes to Understand Degradation of Organic Contaminants in Ground Water

EPA Science Inventory

Stable isotopes are a powerful tool to understand biodegradation. However, there are two interactions that can substantially confuse the interpretation of CSIR data: heterogeneity in flow paths in the aquifer and proximity to NAPL or other source of contamination to ground wate...

Using stable isotopes to examine watershed connectivity to downstream waters

EPA Science Inventory

Water bodies within the USA are protected by the US Clean Water Act when they have a significant nexus to downstream navigable waters. As a research scientist with the US Environmental Protection Agency, I have used water stable isotopes to examine hydrologic connectivity dynami...

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...

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

EPA Science Inventory

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

Best practices for use of stable isotope mixing models in food-web studies

EPA Science Inventory

Stable isotope mixing models are increasingly used to quantify contributions of resources to consumers. While potentially powerful tools, these mixing models have the potential to be misused, abused, and misinterpreted. Here we draw on our collective experiences to address the qu...

STABLE NITROGEN ISOTOPES AS INDICATORS OF ANTHOPOGENIC ACTIVITIES IN SMALL FRESHWATER SYSTEMS

EPA Science Inventory

Stable nitrogen isotope ratios ( 15N) were measured in fish, mussel, and sediment samples taken from 17 small freshwater sites to examine food chain length and trophic position across sites affected by differing levels of anthropogenic activity. Both shoreline development and fis...

The utility of arginine-citrulline stable isotope tracer infusion technique in the assessment of nitric oxide production in MELAS syndrome

USDA-ARS?s Scientific Manuscript database

The correspondence titled “Analytical challenges in the assessment of NO synthesis from L-arginine in the MELAS syndrome” suggested challenges that can limit the utility of stable isotope infusion methodology in assessing NO production....

A Very Much Faster and More Sensitive In Situ Stable Isotope Analysis Instrument

NASA Astrophysics Data System (ADS)

Coleman, M.; Christensen, L. E.; Kriesel, J. M.; Kelly, J. F.; Moran, J. J.; Vance, S.

2016-10-01

We are developing, Capillary Absorption Spectrometry (CAS) for H and O stable isotope analyses, giving > 4 orders of magnitude improved sensitivity, allowing analysis of 5 nano-moles of water and coupled to laser sampling to free water from hydrated minerals and ice.

Contribution of Allochthonous Carbon to American Shad Production in the Mattaponi River, Virginia, Using Stable Isotopes

EPA Science Inventory

Our objective was to quantify the contribution of autochthonous, locally-produced phytoplankton, and allochthonous, terrestrial-derived organic matter (OM) to the production of young-of-year (YOY) American shad using stable isotopes...The results suggest an important link between...

New Isotopic Tracers for Shale Gas and Hydraulic Fracturing Fluids

EPA Pesticide Factsheets

The combined application of geochemistry, stable isotopes (δ18O, δ2H), strontium isotopes (87Sr/86Sr), boron isotopes (δ11B), and radium isotopes (228Ra/226Ra) provides a unique methodology for tracing and monitoring shale gas and fracking fluids in the environment.

Insights from quantitative metaproteomics and protein-stable isotope probing into microbial ecology.

PubMed

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

2013-10-01

The recent development of metaproteomics has enabled the direct identification and quantification of expressed proteins from microbial communities in situ, without the need for microbial enrichment. This became possible by (1) significant increases in quality and quantity of metagenome data and by improvements of (2) accuracy and (3) sensitivity of modern mass spectrometers (MS). The identification of physiologically relevant enzymes can help to understand the role of specific species within a community or an ecological niche. Beside identification, relative and absolute quantitation is also crucial. We will review label-free and label-based methods of quantitation in MS-based proteome analysis and the contribution of quantitative proteome data to microbial ecology. Additionally, approaches of protein-based stable isotope probing (protein-SIP) for deciphering community structures are reviewed. Information on the species-specific metabolic activity can be obtained when substrates or nutrients are labeled with stable isotopes in a protein-SIP approach. The stable isotopes ((13)C, (15)N, (36)S) are incorporated into proteins and the rate of incorporation can be used for assessing the metabolic activity of the corresponding species. We will focus on the relevance of the metabolic and phylogenetic information retrieved with protein-SIP studies and for detecting and quantifying the carbon flux within microbial consortia. Furthermore, the combination of protein-SIP with established tools in microbial ecology such as other stable isotope probing techniques are discussed.

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

USGS Publications Warehouse

Rast, Walter; Sutton, J.E.

1989-01-01

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

Stable isotope discrimination factors and between-tissue isotope comparisons for bone and skin from captive and wild green sea turtles (Chelonia mydas).

PubMed

Turner Tomaszewicz, Calandra N; Seminoff, Jeffrey A; Price, Mike; Kurle, Carolyn M

2017-11-30

The ecological application of stable isotope analysis (SIA) relies on taxa- and tissue-specific stable carbon (Δ 13 C) and nitrogen (Δ 15 N) isotope discrimination factors, determined with captive animals reared on known diets for sufficient time to reflect dietary isotope ratios. However, captive studies often prohibit lethal sampling, are difficult with endangered species, and reflect conditions not experienced in the wild. We overcame these constraints and determined the Δ 13 C and Δ 15 N values for skin and cortical bone from green sea turtles (Chelonia mydas) that died in captivity and evaluated the utility of a mathematical approach to predict discrimination factors. Using stable carbon (δ 13 C values) and nitrogen (δ 15 N values) isotope ratios from captive and wild turtles, we established relationships between bone stable isotope (SI) ratios and those from skin, a non-lethally sampled tissue, to facilitate comparisons of SI ratios among studies using multiple tissues. The mean (±SD) Δ 13 C and Δ 15 N values (‰) between skin and bone from captive turtles and their diet (non-lipid-extracted) were 2.3 ± 0.3 and 4.1 ± 0.4 and 2.1 ± 0.6 and 5.1 ± 1.1, respectively. The mathematically predicted Δ 13 C and Δ 15 N values were similar (to within 1‰) to the experimentally derived values. The mean δ 15 N values from bone were higher than those from skin for captive (+1.0 ± 0.9‰) and wild (+0.8 ± 1.0‰) turtles; the mean δ 13 C values from bone were lower than those from skin for wild turtles (-0.6 ± 0.9‰), but the same as for captive turtles. We used linear regression equations to describe bone vs skin relationships and create bone-to-skin isotope conversion equations. For sea turtles, we provide the first (a) bone-diet SI discrimination factors, (b) comparison of SI ratios from individual-specific bone and skin, and (c) evaluation of the application of a mathematical approach to predict stable isotope discrimination factors. Our approach opens the door for future studies comparing different tissues, and relating SI ratios of captive to wild animals. Copyright © 2017 John Wiley & Sons, Ltd.

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 nature of variation and the physiological processes responsible for stable isotope values from biological tissues are critical for their interpretation. Change in carbon and nitrogen stable isotopes (ΔδC13, Δδ15N) after lipid extraction for Tufted Puffins (Fratercula cirrhata) collected July 2010 at Attu Island, Aleutians.

Use of stable carbon isotope ratios to determine the source of cypermethrin in so-called natural plant extract formulations used for organic farming.

PubMed

Kawashima, Hiroto; Kariya, Takuro

2017-03-01

Some natural plant extract formulations (NPEFs, also referred to as essential oils) used in organic farming have been shown to contain synthetic pesticides. We obtained samples of four NPEFs (Muso, Hekiro, Kensogen-Ten, and Nurse Green) that were contaminated with the synthetic pyrethroid cypermethrin, and we used gas chromatography coupled with combustion, cryofocusing, and isotope ratio mass spectrometry to determine the stable carbon isotope ratios (δ 13 C) for the cypermethrin in the four NPEF samples, as well as in ten cypermethrin reagents and two commercial pesticide formulations (Agrothrin emulsion and Agrothrin water-dispersible powder). Our goal was to identify the source of the cypermethrin in the NPEFs. Cryofocusing markedly sharpened the cypermethrin peak and thus improved the accuracy and precision of the determined δ 13 C values. The δ 13 C values (± SD) of the 16 cypermethrin samples ranged from -28.3 ± 0.2 to -24.5 ± 0.2 ‰. Surprisingly, the four NPEFs showed similar δ 13 C values (-26.8 to -27.3 ‰), suggesting that the cypermethrin in all the samples came from the same source (either the same chemical reaction or the same primary material). This possibility was supported by previously published results. In addition, the δ 13 C values of the two commercial pesticides were similar to the values for the NPEFs, suggesting that the commercial pesticides had been diluted and sold as NPEFs.

Martian stable isotopes: volatile evolution, climate change and exobiological implications

NASA Technical Reports Server (NTRS)

Jakosky, B. M.

1999-01-01

Measurements of the ratios of stable isotopes in the martian atmosphere and crust provide fundamental information about the evolution of the martian volatile and climate system. Current best estimates of the isotope ratios indicate that there has been substantial loss of gases to space and exchange of gases between the atmosphere and the crust throughout geologic time; exchange may have occurred through circulation of water in hydrothermal systems. Processes of volatile evolution and exchange will fractionate the isotopes in a manner that complicates the possible interpretation of isotopic data in terms of any fractionation that may have been caused by martian biota, and must be understood first. Key measurements are suggested that will enhance our understanding of the non-biological fractionation of the isotopes and of the evolution of the martian volatile system.

Linking stable isotopes and biochemical responses in Balanus glandula under sewage influence.

PubMed

Laitano, M V; Díaz-Jaramillo, M; Rodriguez, Y E; Ducós, E; Panarello, H O; Fernández-Gimenez, A V

2018-02-01

In the present study, we analyzed the influence of untreated sewage exposure on carbon (δ13C) and nitrogen (δ15N) isotopic composition and several biochemical responses in the barnacle Balanus glandula. The main objective was to evaluate whether changes in stable isotopes signature do reflect biochemical sub-lethal effects in a sewage influence gradient. Stable isotopes analysis showed differences in isotope signatures between close sewage influence and distant sites, being δ13C signatures stronger than that of δ15N. Regarding biochemical effects, although organisms close to the effluent would be clearly exposed to contaminants (increased GST activity) the oxidative stress would not be too evident (peroxidases and ACAP not affected). The most affected physiological aspect was the digestive one, reflected in increased alkaline proteases and lipases activities. A clear relation between δ15N and GST activity was found, showing to δ15N as an indicator of potential exposure to chemical contaminants.

"Application of Tunable Diode Laser Spectrometry to Isotopic Studies for Exobiology"

NASA Technical Reports Server (NTRS)

Sauke, Todd B.

1999-01-01

Computer-controlled electrically-activated valves for rapid gas-handling have been incorporated into the Stable Isotope Laser Spectrometer (SILS) which now permits rapid filling and evacuating of the sample and reference gas cells, Experimental protocols have been developed to take advantage of the fast gas handling capabilities of the instrument and to achieve increased accuracy which results from reduced instrumental drift during rapid isotopic ratio measurements. Using these protocols' accuracies of 0.5 del (0.05%) have been achieved in measurements of 13C/12C in carbon dioxide. Using the small stable isotope laser spectrometer developed in a related PIDDP project of the Co-I, protocols for acquisition of rapid sequential calibration spectra were developed which resulted in 0.5 del accuracy also being achieved in this less complex instrument. An initial version of software for automatic characterization of tunable diode lasers has been developed and diodes have been characterized in order to establish their spectral output properties. A new state-of-the-art high operating temperature (200 K) mid infrared diode laser was purchased (through NASA procurement) and characterized. A thermo-electrically cooled mid infrared tunable diode laser system for use with high temperature operation lasers was developed. In addition to isotopic ratio measurements of carbon and oxygen, measurements of a third biologically important element (15N/14N in N2O gas) have been achieved to a preliminary accuracy of about 0.2%. Transfer of the basic SILS technology to the commercial sector is proceeding under an unfunded Space Act Agreement between NASA and SpiraMed, a medical diagnostic instrument company. Two patents have been issued. Foreign patents based on these two US patents have been applied for and are expected to be issued. A preliminary design was developed for a thermo-electrically cooled SILS instruments for application to planetary space flight exploration missions.

Determination of the δ34S of Total Sulfur in Solids: RSIL Lab Code 1800

USGS Publications Warehouse

Revesz, Kinga; Coplen, Tyler B.

2006-01-01

The purpose of Reston Stable Isotope Laboratory Lab (RSIL) Code 1800 is to determine the δ(34S/32S), abbreviated as δ34S, of total sulfur in a solid sample. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total sulfur in a solid sample into SO2 gas. The EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines the relative difference in stable sulfur isotope-amount ratio (34S/32S) of the product SO2 gas. The combustion is quantitative; no isotopic fractionation is involved. Samples are placed in tin capsules and loaded into a Costech Zero-Blank Autosampler on the EA. Under computer control, samples are dropped into a heated tube reaction tube that combines both the oxidation and the reduction reactions. The combustion takes place in a He atmosphere that contains an excess of oxygen gas at the oxidation zone at the top of the reaction tube. Combustion products are transported by a He carrier through the reduction zone at the bottom of the reaction tube to remove excess oxygen and through a separate drying tube to remove any water. The gas-phase products, mainly CO2, N2, and SO2, are separated by a gas chromatograph (GC). The gas is then introduced into the isotope-ratio mass spectrometer (IRMS) through a Thermo-Finnigan ConFlo II interface, which also is used to inject SO2 reference gas and He for sample dilution. The IRMS is a Thermo-Finnigan DeltaPlus CF-IRMS. It has a universal triple collector with two wide cups and a narrow cup in the middle. It is capable of measuring mass/charge (m/z) 64 and 66 simultaneously. The ion beams from SO2 are as follows: m/z 64 = SO2 = 32S16O16O; and m/z 66 = SO2 = 34S16O16O primarily.

Application of 1013 ohm Faraday cup current amplifiers for boron isotopic analyses by solution mode and laser ablation multicollector inductively coupled plasma mass spectrometry.

PubMed

Lloyd, Nicholas S; Sadekov, Aleksey Yu; Misra, Sambuddha

2018-01-15

Boron isotope ratios (δ 11 B values) are used as a proxy for seawater paleo-pH, amongst several other applications. The analytical precision can be limited by the detection of low intensity ion beams from limited sample amounts. High-gain amplifiers offer improvements in signal/noise ratio and can be used to increase measurement precision and reduce sample amounts. 10 13 ohm amplifier technology has previously been applied to several radiogenic systems, but has thus far not been applied to non-traditional stable isotopes. Here we apply 10 13 ohm amplifier technology for the measurement of boron isotope ratios using solution mode MC-ICP-MS and laser ablation mode (LA-)MC-ICP-MS techniques. Precision is shown for reference materials as well as for low-volume foraminifera samples. The baseline uncertainty for a 0.1 pA 10 B + ion beam is reduced to <0.1 ‰ for a typical measurement period. The external precision is better than 0.2 ‰ (2SD) for δ 11 B measurements for solution samples containing as little as 0.8 ng total boron. For in situ microanalyses with LA-MC-ICP-MS, the external precision of 11 B/ 10 B from an in-house calcite standard was 1 ‰ (2SD) for individual spot analyses, and 0.3 ‰ for the mean of ≥10 replicate spot analyses. 10 13 ohm amplifier technology is demonstrated to offer advantages for the determination of δ 11 B values by both MC-ICP-MS and LA-MC-ICP-MS for small samples of biogenic carbonates, such as foraminifera shells. 10 13 ohm amplifier technology will also be of benefit to other non-traditional stable isotope measurements. Copyright © 2017 John Wiley & Sons, Ltd.

Stable isotope signatures in bulk samples from two soils with contrasting characteristics. What do they tell about ongoing pedogenic processes?

NASA Astrophysics Data System (ADS)

Jiménez-Morillo, Nicasio T.; dos Anjos Leal, Otávio; Knicker, Heike; Pinheiro Dick, Deborah; González-Vila, Francisco J.; González-Pérez, José A.

2014-05-01

Isotopic ratio mass spectrometry (IRMS) has been proven as a promising tool for the monitoring of biogeochemical processes in soil. In this work, stable isotope signatures of light elements δ15N, δ13C, δ18O and δD were determined for two soils with contrasting characteristics in terms of climate, vegetation, land use and management. The studied soils were a Cambisol from a subtropical area (Paraná region, South Brazil) and an Arenosol from a Mediterranean climate (Andalusia, South Spain). A Flash 2000 HT (N, C, S, H and O) elemental analyzer (Thermo Scientific) coupled to a Delta V Advantage IRMS (Thermo Scientific) was used. Isotopic ratios are reported as parts per thousand (o ) deviations from appropriate standards recognized by the international atomic energy agency (IAEA). In a first approach we took advantage of the well-known different δ13C signature between plants using either the C4 or C3 carbon fixation pathway (O'Leary, 1981). The Arenosol (Spain) revealed a δ13C signature which is clearly in the range of C3 plants (-26 to -30 o ). Different plant canopies (tree, shrubs or ferns) caused only slight variations δ13C (STD= 0.98). In contrast, the Cambisol (Brazil) showed less depletion of the heavier carbon isotope corresponding to C4 predominant vegetation. In addition an increase from -19 o in the soil surface (0 - 5 cm) to -16 o in the subsoil (20 - 30 cm) was observed in line with a recent (2 years old) shift of the land use from the predominant C4 grassland to eucalypt (C3) cultivation. Crossplots of δ15N vs. δ18O may provide information about nitrate (NO3-) sources and N cycling (Kendall, 1998). In the Mediterranean Arenosol this signal (δ18O = 30o δ15N = 2o ) was found compatible with a predominant nitrate atmospheric deposition, whereas the signal in the Brazilian Cambisol pointed to the use of a mineral N fertilization with signs of denitrification processes (δ18O = 13o δ15N = 9o ). No conclusive results could be obtained from the δD isotopic signature probably due to overlapping of the δD signals from the organic and the mineral fractions. For a more detailed analysis steps allowing their separation are necessary (Ruppenthal et al. (2013) and references therein). Kendall, C. 1998. Tracing nitrogen sources and cycling in catchments. In Isotopes Tracers in Catchments Hydrology (C. Kendall and J. J. McDonnell, Eds). Elsevier Science B. V., Amsterdam, 519-576. O'Leary, M.H. 1981. Carbon isotope fraction in plants. Phytochemistry 20: 553-567. Ruppenthal, M., Oelmann, Y., Wilcke, W. 2013. Optimized demineralization technique for the measurement of stable isotope ratios of nonexchangeable H in soil organic matter. Environmental Science and Technology 47: 949-957.

Influence of weather on the stable isotopic ratios of wines: Tools for weather/climate reconstruction?

NASA Astrophysics Data System (ADS)

Ingraham, Neil L.; Caldwell, Eric A.

1999-01-01

Precipitation, local ground water, soil water, atmospheric water vapor, grape leaf and grape berry water just prior to harvest, and grape must during the wine-making process, from the Napa Valley in northern California were collected for stable isotopic analysis. In addition, 27 red wines and 4 white wines produced in the Napa Valley, and 8 red wines produced in Livermore Valley located over 110 km to the southeast, were analyzed for both oxygen and hydrogen isotopic compositions. The isotopic compositions of the grape leaf water fall on a transpiration line with a slope of 2.1, while those of the grape berry water fall on a transpiration line with a slope of 2.8. The stable isotopic compositions of the 27 red wines from the Napa Valley range from -3 to +20‰ in δD and from +4.6 to + 10.2‰ in δ18O and plot along a line described by δD = 3.4 δ18O - 17.2. The maximum difference in the stable oxygen composition between two wineries 110 km apart is only 1.4‰, while the differences between the vintage years within each winery are 4.8 and 5.8‰ in δ18O. The stable isotopic composition of the grape water is controlled by transpiration in the weeks prior to harvest, overshadowing all other effects. As a result of the timing of harvest, the red wines are some 4 to 5‰ more enriched in δ18O than the white wines.

Escherichia coli cell-free protein synthesis and isotope labeling of mammalian proteins.

PubMed

Terada, Takaho; Yokoyama, Shigeyuki

2015-01-01

This chapter describes the cell-free protein synthesis method, using an Escherichia coli cell extract. This is a cost-effective method for milligram-scale protein production and is particularly useful for the production of mammalian proteins, protein complexes, and membrane proteins that are difficult to synthesize by recombinant expression methods, using E. coli and eukaryotic cells. By adjusting the conditions of the cell-free method, zinc-binding proteins, disulfide-bonded proteins, ligand-bound proteins, etc., may also be produced. Stable isotope labeling of proteins can be accomplished by the cell-free method, simply by using stable isotope-labeled amino acid(s) in the cell-free reaction. Moreover, the cell-free protein synthesis method facilitates the avoidance of stable isotope scrambling and dilution over the recombinant expression methods and is therefore advantageous for amino acid-selective stable isotope labeling. Site-specific stable isotope labeling is also possible with a tRNA molecule specific to the UAG codon. By the cell-free protein synthesis method, coupled transcription-translation is performed from a plasmid vector or a PCR-amplified DNA fragment encoding the protein. A milligram quantity of protein can be produced with a milliliter-scale reaction solution in the dialysis mode. More than a thousand solution structures have been determined by NMR spectroscopy for uniformly labeled samples of human and mouse functional domain proteins, produced by the cell-free method. Here, we describe the practical aspects of mammalian protein production by the cell-free method for NMR spectroscopy. © 2015 Elsevier Inc. All rights reserved.

Isotope reference materials

USGS Publications Warehouse

Coplen, Tyler B.

2010-01-01

Measurement of the same isotopically homogeneous sample by any laboratory worldwide should yield the same isotopic composition within analytical uncertainty. International distribution of light element isotopic reference materials by the International Atomic Energy Agency and the U.S. National Institute of Standards and Technology enable laboratories to achieve this goal.

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

PubMed

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

2006-01-01

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

MixSIAR: A Bayesian stable isotope mixing model for characterizing intrapopulation niche variation

EPA Science Inventory

Background/Question/Methods The science of stable isotope mixing models has tended towards the development of modeling products (e.g. IsoSource, MixSIR, SIAR), where methodological advances or syntheses of the current state of the art are published in parity with software packa...

USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS

EPA Science Inventory

We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

Interannual Variation in Stable Carbon and Nitrogen Isotope Biogeochemistry of the Mattaponi River, Virginia

EPA Science Inventory

This manuscript addresses the difficult issue of identifying the origin of particulate organic matter (POM) in estuaries . . . The objectives of this study were to quantify spatial and temporal variability of the C and N stable isotope composition of suspended POM, and to identif...

NCL-01: Nanomedicine Drug Release Study in Human Plasma Using Stable Isotope Tracer Ultrafiltration Assay (SITUA)  | Frederick National Laboratory for Cancer Research

Cancer.gov

The Nanotechnology Characterization Laboratory will evaluate drug release from a nanoparticulate formulation in vitro in human plasma, using a novel stable isotope tracer ultrafiltration assay (SITUA) developed at the laboratory. The SITUA is a metho

PHOTOCHEMICALLY-INDUCED ALTERATION OF STABLE CARBON ISOTOPE RATIOS (DELTA C-13) IN TERRIGENOUS DISSOLVED ORGANIC CARBON

EPA Science Inventory

Exposure of riverine waters to natural sunlight initiated alterations in stable carbon isotope ratios (delta C-13) of the associated dissolved organic carbon (DOC). Water samples were collected from two compositionally distinct coastal river systems in the southeastern United Sta...

Stable isotopes to trace food web stressors: Is space the final frontier?

EPA Science Inventory

To support community decision-making, we need to evaluate sources of stress and impact at a variety of spatial scales, whether local or watershed-based. Increasingly, we are using stable isotope-based approaches to determine those scales of impact, and using these approaches in v...

Stable isotope enrichment in laboratory ant colonies: effects of colony age, metamorphosis, diet, and fat storage

USDA-ARS?s Scientific Manuscript database

Ecologists use stable isotopes to infer diets and trophic levels of animals in food webs, yet some assumptions underlying these inferences have not been thoroughly tested. We used laboratory-reared colonies of Solenopsis invicta Buren (Formicidae: Solenopsidini) to test the effects of metamorphosis,...

Habitat use and trophic position effects on contaminant bioaccumulation in fish indicated by stable isotope composition

EPA Science Inventory

The objective of our study was to determine the relationship between fish tissue stable isotope composition and total mercury or polychlorinated biphenyl (PCB) concentrations in a Great Lakes coastal food web. We sampled two resident fishes, Yellow Perch (Perca flavescens) and Bl...

Stable Isotope Values of Nitrogen and Carbon in Particulate Matter: Data

EPA Science Inventory

Data set from “Patterns in stable isotope values of nitrogen and carbon in particulate matter from the Northwest Atlantic Continental Shelf, from the Gulf of Maine to Cape Hatteras” by Oczkowski et al. These are the data upon which all results and conclusion are made...

Module 5: Applications of Stable Isotope Analyses: Data Interpretation and Data Quality Issues

EPA Science Inventory

When organic contaminants such as benzene, TCE or MTBE are degraded, the ratio of the stable isotopes of carbon in the organic contaminants will often change in a predictable fashion. In the last ten years, advances in analytical chemistry have made it possible to measure these ...

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...

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...

APPLICATION OF STABLE CARBON AND HYDROGEN ISOTOPIC TECHNIQUES FOR MONITORING BIODEGRADATION OF MTBE IN THE FIELD

EPA Science Inventory

A significant challenge in environmental studies is to determine the onset and extent of MTBE bioremediation at an affected site, which may involve indirect approaches such as microcosm verification of microbial activities at a given site. Stable isotopic fractionation is cha...

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...

Tracing the origins, migrations, and other movements of fishes using stable isotopes

EPA Science Inventory

Although stable isotope studies are increasingly used to trace fish origin, migration, and movement, the approach has not been as widely adopted as extrinsic marking and tagging. This is, at least in part, because many fishery scientists do not have a background in biogeochemistr...

USE OF CARBON STABLE ISOTOPE TO INVESTIGATE CHLOROMETHANE FORMATION IN THE ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE

EPA Science Inventory

Carbon stable isotope trichloroethylene (¹³C TCE) was used to investigate the formation of chloromethane (CM) during the electrolytic dechlorination of trichloroethylene (TCE) at a granular-graphite packed cathode. A method was developed to use a conventional GC/MS to ...

Stable Isotope Signatures of Middle Palaeozoic Ahermatypic Rugose Corals - Deciphering Secondary Alteration, Vital Fractionation Effects, and Palaeoecological Implications.

PubMed

Jakubowicz, Michal; Berkowski, Blazej; López Correa, Matthias; Jarochowska, Emilia; Joachimski, Michael; Belka, Zdzislaw

2015-01-01

This study investigates stable isotope signatures of five species of Silurian and Devonian deep-water, ahermatypic rugose corals, providing new insights into isotopic fractionation effects exhibited by Palaeozoic rugosans, and possible role of diagenetic processes in modifying their original isotopic signals. To minimize the influence of intraskeletal cements on the observed signatures, the analysed specimens included unusual species either devoid of large intraskeletal open spaces ('button corals': Microcyclus, Palaeocyclus), or typified by particularly thick corallite walls (Calceola). The corals were collected at four localities in the Holy Cross Mountains (Poland), Mader Basin (Morocco) and on Gotland (Sweden), representing distinct diagenetic histories and different styles of diagenetic alteration. To evaluate the resistance of the corallites to diagenesis, we applied various microscopic and trace element preservation tests. Distinct differences between isotopic compositions of the least-altered and most-altered skeleton portions emphasise a critical role of material selection for geochemical studies of Palaeozoic corals. The least-altered parts of the specimens show marine or near-marine stable isotope signals and lack positive correlation between δ13C and δ18O. In terms of isotopic fractionation mechanisms, Palaeozoic rugosans must have differed considerably from modern deep-water scleractinians, typified by significant depletion in both 18O and 13C, and pronounced δ13C-δ18O co-variance. The fractionation effects exhibited by rugosans seem similar rather to the minor isotopic effects typical of modern non-scleractinian corals (octocorals and hydrocorals). The results of the present study add to growing evidence for significant differences between Scleractinia and Rugosa, and agree with recent studies indicating that calcification mechanisms developed independently in these two groups of cnidarians. Consequently, particular caution is needed in using scleractinians as analogues in isotopic studies of extinct coral lineages. Answering some of the pertinent palaeoecological questions, such as that of the possibility of photosymbiosis in Palaeozoic corals, may not be possible based on stable isotope data.

Simulating Stable Isotope Ratios in Plumes of Groundwater Pollutants with BIOSCREEN-AT-ISO.

PubMed

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

2017-03-01

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

Eddy Covariance measurements of stable isotopes (δD and δ18O) in water vapor

NASA Astrophysics Data System (ADS)

Braden-Behrens, Jelka; Knohl, Alexander

2017-04-01

Stable isotopes are a promising tool to enhance our understanding of ecosystem gas exchanges. Studying 18O and 2H in water vapour (H2Ov) can e.g. help partitioning evapotranspiration into its components. With recent developments in laser spectroscopy direct Eddy Covariance (EC) measurements for investigating fluxes of stable isotopologues became feasible. So far very few case studies have applied the EC method to measure stable isotopes in water vapor. We continuously measure fluxes of water vapor isotopologues with the EC method in a managed beech forest in Thuringia, Germany, since autumn 2015 using the following setup: An off-axis integrated cavity output water vapor isotope analyzer (WVIA, Los Gatos Research. Inc, USA) measures the water vapour concentration and its isotopic composition (δD and δ18O). The instrument, that was optimized for high flow rates (app. 4slpm) to generate high frequency (2Hz) measurements, showed sufficient precision with Allan Deviations of app. 0.12 ‰ for δD and 0.06 ‰ for δ18O for averaging periods of 100s. The instrument was calibrated hourly using a high-flow optimized version of the water vapor isotope standard source (WVISS, Los Gatos Research. Inc, USA) that provides water vapor with known isotopic composition for a large range of different concentrations. Our calibration scheme includes a near continuous concentration range calibration instead of a simple 2 or 3-point calibration to face the analyzers strong concentration dependency within a range of app. 6 000 to 16 000 ppm in winter and app. 8 000 to 23 000 ppm in summer. In the used setup, the high-flow and high-frequency optimized water vapor isotope analyzer (WVIA) showed suitable characteristics (Allan deviation and spectral energy distribution) to perform Eddy covariance measurements of stable isotopes in H2Ov. Thus, this novel instrument for EC measurements of water vapor isotopologues provides a new opportunity for studying the hydrological cycle in long-term observation networks like Fluxnet and ICOS.

Investigating Uranium Mobility Using Stable Isotope Partitioning of 238U/235U and a Reactive Transport Model

NASA Astrophysics Data System (ADS)

Bizjack, M.; Johnson, T. M.; Druhan, J. L.; Shiel, A. E.

2015-12-01

We report a numerical reactive transport model which explicitly incorporates the effectively stable isotopes of uranium (U) and the factors that influence their partitioning in bioactive systems. The model reproduces trends observed in U isotope ratios and concentration measurements from a field experiment, thereby improving interpretations of U isotope ratios as a tracer for U reactive transport. A major factor contributing to U storage and transport is its redox state, which is commonly influenced by the availability of organic carbon to support metal-reducing microbial communities. Both laboratory and field experiments have demonstrated that biogenic reduction of U(VI) fractionates the stable isotope ratio 238U/235U, producing an isotopically heavy solid U(IV) product. It has also been shown that other common reactive transport processes involving U do not fractionate isotopes to a consistently measurable level, which suggests the capacity to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U ratios. A recent study of a U bioremediation experiment at the Rifle IFRC site (Colorado, USA) applied Rayleigh distillation models to quantify U stable isotope fractionation observed during acetate amendment. The application of these simplified models were fit to the observations only by invoking a "memory-effect," or a constant source of low-concentration, unfractionated U(VI). In order to more accurately interpret the measured U isotope ratios, we present a multi-component reactive transport model using the CrunchTope software. This approach is capable of quantifying the cycling and partitioning of individual U isotopes through a realistic network of transport and reaction pathways including reduction, oxidation, and microbial growth. The model incorporates physical heterogeneity of the aquifer sediments through zones of decreased permeability, which replicate the observed bromide tracer, major ion chemistry, U concentration, and U isotope ratios. These results suggest that the rate-limited transport properties of U in the Rifle aquifer are governed by the presence of low-permeability regions in the modeling domain and that these zones are responsible for the suggested "memory" effect observed in previous U isotope studies at this site.

Toward a simple, repeatable, non-destructive approach to measuring stable-isotope ratios of water within tree stems

NASA Astrophysics Data System (ADS)

Raulerson, S.; Volkmann, T.; Pangle, L. A.

2017-12-01

Traditional methodologies for measuring ratios of stable isotopes within the xylem water of trees involve destructive coring of the stem. A recent approach involves permanently installed probes within the stem, and an on-site assembly of pumps, switching valves, gas lines, and climate-controlled structure for field deployment of a laser spectrometer. The former method limits the possible temporal resolution of sampling, and sample size, while the latter may not be feasible for many research groups. We present results from initial laboratory efforts towards developing a non-destructive, temporally-resolved technique for measuring stable isotope ratios within the xylem flow of trees. Researchers have used direct liquid-vapor equilibration as a method to measure isotope ratios of the water in soil pores. Typically, this is done by placing soil samples in a fixed container, and allowing the liquid water within the soil to come into isotopic equilibrium with the headspace of the container. Water can also be removed via cryogenic distillation or azeotropic distillation, with the resulting liquid tested for isotope ratios. Alternatively, the isotope ratios of the water vapor can be directly measured using a laser-based water vapor isotope analyzer. Well-established fractionation factors and the isotope ratios in the vapor phase are then used to calculate the isotope ratios in the liquid phase. We propose a setup which would install a single, removable chamber onto a tree, where vapor samples could non-destructively and repeatedly be taken. These vapor samples will be injected into a laser-based isotope analyzer by a recirculating gas conveyance system. A major part of what is presented here is in the procedure of taking vapor samples at 100% relative humidity, appropriately diluting them with completely dry N2 calibration gas, and injecting them into the gas conveyance system without inducing fractionation in the process. This methodology will be helpful in making temporally resolved measurements of the stable isotopes in xylem water, using a setup that can be easily repeated by other research groups. The method is anticipated to find broad application in ecohydrological analyses, and in tracer studies aimed at quantifying age distributions of soil water extracted by plant roots.

Trophic position of soil nematodes in boreal forests as indicated by stable isotope analysis

NASA Astrophysics Data System (ADS)

Kudrin, Alexey; Tsurikov, Sergey

2016-04-01

Despite the well-developed trophic classification of soil nematodes, their position in soil food webs is still little understood. Observed deviations from the typical feeding strategy indicate that a simplified trophic classification probably does not fully reflect actual trophic interactions. Furthermore, the extent and functional significance of nematodes as prey for other soil animals remains unknown. Stable isotope analysis (SIA) is powerful tool for investigating the structure of soil food webs, but its application to the study of soil nematodes has been limited to only a few studies. We used stable isotope analysis to gain a better understanding of trophic links of several groups of soil nematodes in two boreal forests on albeluvisol. We investigated four taxonomic groups of nematodes: Mononchida, Dorylaimida, Plectidae and Tylenchidae (mostly from the genus Filenchus), that according to the conventional trophic classification represent predators, omnivores, bacterivores and root-fungal feeders, respectively. To assess the trophic position of nematodes, we used a comparison against a set of reference species including herbivorous, saprophagous and predatory macro-invertebrates, oribatid and mesostigmatid mites, and collembolans. Our results suggest that trophic position of the investigated groups of soil nematodes generally corresponds to the conventional classification. All nematodes were enriched in 13C relative to Picea abies roots and litter, and mycorrhizal fungal mycelium. Root-fungal feeders Tylenchidae had δ15N values similar to those of earthworms, enchytraeids and Entomobrya collembolans, but slightly lower δ13C values. Bacterivorous Plectidae were either equal or enriched in 15N compared with saprophagous macroinvertebrates and most mesofauna species. Omnivorous Dorylaimida and predatory Mononchida were further enriched in 15N and their isotopic signature was similar to that of predatory arthropods. These data confirm a clear separation of nematodes into saprophagous/microbial feeders (Tylenchidae and Plectidae) and predators (Mononchida and Dorylaimida). Furthermore, they suggest that Mononchida and Dorylaimida use different sources of carbon, though exact trophic links remain unclear. As a rule, nematodes were either equal or higher in δ15N values relative to most microbivorous microarthropods, contradicting an emerging view that soil nematodes can be an important prey for a wide range of oribatid mites and collembolans. Patterns of the isotopic signatures suggest that soil nematodes and the bulk of soil animals depend on resources derived from a dominating upper-canopy tree (Picea abies) via the detrital, rather than mycorrhizal pathway.

Predicting rates of isotopic turnover across the animal kingdom: a synthesis of existing data.

PubMed

Thomas, Stephen M; Crowther, Thomas W

2015-05-01

The stable isotopes of carbon ((12)C, (13)C) and nitrogen ((14)N, (15)N) represent powerful tools in food web ecology, providing a wide range of dietary information in animal consumers. However, identifying the temporal window over which a consumer's isotopic signature reflects its diet requires an understanding of elemental incorporation, a process that varies from days to years across species and tissue types. Though theory predicts body size and temperature are likely to control incorporation rates, this has not been tested empirically across a morphologically and phylogenetically diverse range of taxa. Readily available estimates of this relationship would, however, aid in the design of stable isotope food web investigations and improve the interpretation of isotopic data collected from natural systems. Using literature-derived turnover estimates from animal species ranging in size from 1 mg to 2000 kg, we develop a predictive tool for stable isotope ecologists, allowing for estimation of incorporation rates in the structural tissues of entirely novel taxa. In keeping with metabolic scaling theory, we show that isotopic turnover rates of carbon and nitrogen in whole organisms and muscle tissue scale allometrically with body mass raised approximately to the power -0.19, an effect modulated by body temperature. This relationship did not, however, apply to incorporation rates in splanchnic tissues, which were instead dependent on the thermoregulation tactic employed by an organism, being considerably faster in endotherms than ectotherms. We believe the predictive turnover equations we provide can improve the design of experiments and interpretation of results obtained in future stable isotopic food web studies. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Continual in situ monitoring of pore water stable isotopes in the subsurface

NASA Astrophysics Data System (ADS)

Volkmann, T. H. M.; Weiler, M.

2014-05-01

Stable isotope signatures provide an integral fingerprint of origin, flow paths, transport processes, and residence times of water in the environment. However, the full potential of stable isotopes to quantitatively characterize subsurface water dynamics is yet unfolded due to the difficulty in obtaining extensive, detailed, and repeated measurements of pore water in the unsaturated and saturated zone. This paper presents a functional and cost-efficient system for non-destructive continual in situ monitoring of pore water stable isotope signatures with high resolution. Automatic controllable valve arrays are used to continuously extract diluted water vapor in soil air via a branching network of small microporous probes into a commercial laser-based isotope analyzer. Normalized liquid-phase isotope signatures are then obtained based on a specific on-site calibration approach along with basic corrections for instrument bias and temperature dependent isotopic fractionation. The system was applied to sample depth profiles on three experimental plots with varied vegetation cover in southwest Germany. Two methods (i.e., based on advective versus diffusive vapor extraction) and two modes of sampling (i.e., using multiple permanently installed probes versus a single repeatedly inserted probe) were tested and compared. The results show that the isotope distribution along natural profiles could be resolved with sufficiently high accuracy and precision at sampling intervals of less than four minutes. The presented in situ approaches may thereby be used interchangeably with each other and with concurrent laboratory-based direct equilibration measurements of destructively collected samples. It is thus found that the introduced sampling techniques provide powerful tools towards a detailed quantitative understanding of dynamic and heterogeneous shallow subsurface and vadose zone processes.

Precise and accurate isotope ratio measurements by ICP-MS.

PubMed

Becker, J S; Dietze, H J

2000-09-01

The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target.

Stable oxygen and carbon isotope characteristics in speleothems from Southern Africa - how good are they?

NASA Astrophysics Data System (ADS)

Holmgren, K.

2009-04-01

Much remains to be understood about the interaction between the African climate system, its surrounding ocean-atmosphere climate variability and the global climate system. A better understanding of the regional climate evolution is crucial for understanding global climate dynamics and issues surrounding environmental change throughout Africa and a prerequisite for increasing climate forecasting capabilities for the region. As part of developing this understanding, a longer term perspective that reaches beyond the information available from instrumental records is required. Speleothems are frequently abundant in southern Africa. Quite a few records are now available, reporting significant changes in climate and environmental conditions over longer and shorter time scales. Conclusions are mainly based on the stable isotopic composition of the speleothems. The interpretation of the stable isotope data is, however, not always straight-forward, since many processes contribute to the observed signal in the speleothem and these processes may influence the signal differently at different spatial and temporal scales. For example was the Makapansgat speleothem oxygen isotope record, originally interpreted as being generally determined by shifts in atmospheric circulation pattern (Lee-Thorp et al. 2001, Holmgren et al. 2003), recently challenged and re-interpreted by Partin et al. (2008) to reflect annual rainfall amounts. Historically, less attention has been paid to the stable carbon isotope composition in speleothems. Today, an increasing number of studies demonstrate the potential of stable carbon variations as providing additional information on climate and environment. Measured variations can be a function of the amount of C3 versus C4 vegetation, vegetation cover and soil biological activity, bedrock proportion, rainfall amount and the drip rate. Clearly the multitudes of plausible processes behind the isotopic composition of speleothems in southern Africa (as well as elsewhere) are a challenge to firm conclusions. However, the need for more globally well dispersed terrestrial palaeoclimatic records; the strong advantages of speleothems to provide precise ages and the empirical experience of successful solutions in previous speleothem research, encourage us to continue research on speleothems from southern Africa. If the understanding of the forcing mechanisms behind measured variables in speleothems can be increased, then there is a great potential for retrieving good climate records from the sub-continent, since the availability of caves containing speleothems is fairly frequent. Available speleothem research from southern Africa will be summarised and potentials and constraints will be discussed. References: Holmgren, K., Lee-Thorp, J.A., Cooper, G.J., Lundblad, K., Partridge, T.C., Scott, L., Sithaldeen, R., Talma, A.S. and Tyson, P.D. 2003: Persistent Millennial-Scale Climatic Variability over the Past 25 thousand Years in Southern Africa. Quaternary Science Reviews, 22, 2311-2326. Lee-Thorp, J.A., Holmgren, K., S.E. Lauritzen, Linge, H., Moberg, A., Partridge, T.C., Stevenson, C. and Tyson P., 2001: Rapid climate shifts in the southern African interior throughout the mid to late Holocene. Geophysical Research Letters 28, 4507-4510. Partin, J.W., Cobb, K.M. and Banner, J.L. 2008: Climate variability recorded in tropical and sub-tropical speleothems. PAGES news, 16, 3, p. 9-10.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magdas, D. A., E-mail: gabriela.cristea@itim-cj.ro; Cristea, G., E-mail: gabriela.cristea@itim-cj.ro; Bot, A.

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

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-09-01

Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment, employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e., equivalent to ~8 ng of amino sugar carbon. Compound-specific stable carbon isotopic analysis of amino sugars obtained from marine sediment extracts indicated that glucosamine and galactosamine were mainly derived from organic detritus, whereas muramic acid showed isotopic imprints from indigenous bacterial activities. The δ13C analysis of amino sugars provides a valuable addition to the biomarker-based characterization of microbial metabolism in the deep marine biosphere, which so far has been lipid oriented and biased towards the detection of archaeal signals.

Enhanced Albumin Synthesis in Severely Burned Adults

DTIC Science & Technology

2010-10-01

changes in albumin syn- thesis in relation to changes in albumin levels. MATERIALS AND METHODS Sterile stable isotope ring-d5- phenylalanine (d5... phenylalanine ) and 5,5,5- d3-ketoisocaproic acid (d3-KIC, potassium salt) were purchased from Cam- bridge Isotope Laboratories (Andover, Mass). Sterile...hypermetabolic state. Stable isotope solutions of d5- phenylalanine (80 2mol I mL j1) and d3-KIC (120 2mol I mLj1) were prepared at the Pharmacy

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.

Every apple has a voice: using stable isotopes to teach about food sourcing and the water cycle

DOE PAGES

Oerter, Erik; Malone, Molly; Putman, Annie; ...

2017-01-01

Agricultural crops such as fruits take up irrigation and meteoric water and incorporate it into their tissue (fruit water) during growth, and the geographic origin of a fruit may be traced by comparing the H and O stable isotope composition ( δ 2H and δ 18O values) of fruit water to the global geospatial distribution of H and O stable isotopes in precipitation. This connection between common fruits and the global water cycle provides an access point to connect with a variety of demographic groups to educate about isotope hydrology and the water cycle. Within the context of a 1-daymore » outreach activity designed for a wide spectrum of participants (high school students, undergraduate students, high school science teachers) we developed introductory lecture materials, in-class participatory demonstrations of fruit water isotopic measurement in real time, and a computer lab exercise to couple actual fruit water isotope data with open-source online geospatial analysis software. Here, we assessed learning outcomes with pre- and post-tests tied to learning objectives, as well as participant feedback surveys. Results indicate that this outreach activity provided effective lessons on the basics of stable isotope hydrology and the water cycle. But, the computer lab exercise needs to be more specifically tailored to the abilities of each participant group. This pilot study provides a foundation for further development of outreach materials that can effectively engage a range of participant groups in learning about the water cycle and the ways in which humans modify the water cycle through agricultural activity.« less

Stable Isotope Identification of Nitrogen Sources for United States (U.S.) Pacific Coast Estuaries

NASA Astrophysics Data System (ADS)

Brown, C. A.; Kaldy, J. E.; Fong, P.; Fong, C.; Mochon Collura, T.; Clinton, P.

2016-02-01

Nutrients are the leading cause of water quality impairments in the United States, and as a result tools are needed to identify the sources of nutrients. We used natural abundance stable isotope data to evaluate nitrogen sources to U.S. west coast estuaries. We collected macroalgae and analyzed these samples for natural abundance of stable isotopes (δ15N) and supplemented this with available data from the literature for estuaries from Mexico to Alaska. Stable isotope ratios of green macroalgae were compared to δ15N of dissolved inorganic nitrogen of oceanic and watershed end members. There was a latitudinal gradient in δ15N of macroalgae with southern estuaries being 7 per mil heavier than northern estuaries. Gradients in isotope data were compared to nitrogen sources estimated by the USGS using the SPARROW model. In California estuaries, the elevation of isotope data appeared to be related to anthropogenic nitrogen sources. In Oregon systems, the nitrogen levels of streams flowing into the estuaries are related to forest cover, rather than to developed land classes. In Oregon estuaries, the δ15N of macroalgae suggested that the ocean and nitrogen-fixing trees in the watersheds were the dominant nitrogen sources with heavier sites located near the estuary mouth. In California estuaries, the gradient was reversed with heavier sites located upriver. In some Oregon estuaries, there was an elevation an elevation of δ15N above marine end members in the vicinity of wastewater treatment facility discharge locations, suggesting isotopes may be useful for distinguishing inputs along an estuarine gradient.

Every apple has a voice: using stable isotopes to teach about food sourcing and the water cycle

NASA Astrophysics Data System (ADS)

Oerter, Erik; Malone, Molly; Putman, Annie; Drits-Esser, Dina; Stark, Louisa; Bowen, Gabriel

2017-07-01

Agricultural crops such as fruits take up irrigation and meteoric water and incorporate it into their tissue (fruit water) during growth, and the geographic origin of a fruit may be traced by comparing the H and O stable isotope composition (δ2H and δ18O values) of fruit water to the global geospatial distribution of H and O stable isotopes in precipitation. This connection between common fruits and the global water cycle provides an access point to connect with a variety of demographic groups to educate about isotope hydrology and the water cycle. Within the context of a 1-day outreach activity designed for a wide spectrum of participants (high school students, undergraduate students, high school science teachers) we developed introductory lecture materials, in-class participatory demonstrations of fruit water isotopic measurement in real time, and a computer lab exercise to couple actual fruit water isotope data with open-source online geospatial analysis software. We assessed learning outcomes with pre- and post-tests tied to learning objectives, as well as participant feedback surveys. Results indicate that this outreach activity provided effective lessons on the basics of stable isotope hydrology and the water cycle. However, the computer lab exercise needs to be more specifically tailored to the abilities of each participant group. This pilot study provides a foundation for further development of outreach materials that can effectively engage a range of participant groups in learning about the water cycle and the ways in which humans modify the water cycle through agricultural activity.

Nitrogen isotope and mass balance approach in the Elbe Estuary

NASA Astrophysics Data System (ADS)

Sanders, Tina; Wankel, Scott D.; Dähnke, Kirstin

2017-04-01

The supply of bioavailable nitrogen is crucial to primary production in the world's oceans. Especially in estuaries, which act as a nutrient filter for coastal waters, microbial nitrogen turnover and removal has a particular significance. Nitrification as well as other nitrogen-based processes changes the natural abundance of the stable isotope, which can be used as proxies for sources and sinks as well as for process identification. The eutrophic Elbe estuary in northern Germany is loaded with fertilizer-derived nitrogen, but management efforts have started to reduce this load effectively. However, an internal nitrate source in turn gained in importance and the estuary changed from a sink to a source of dissolved inorganic nitrogen: Nitrification is responsible for significant estuarine nutrient regeneration, especially in the Hamburg Port. In our study, we aimed to quantify sources and sinks of nitrogen based on a mass and stable isotope budget in the Elbe estuary. A model was developed reproduce internal N-cycling and associated isotope changes. For that approach we measured dissolved inorganic nitrogen (DIN), particulate nitrogen and their stable isotopes in a case study in July 2013. We found an almost closed mass balance of nitrogen, with only low lost or gains which we attribute to sediment resuspension. The isotope values of different DIN components and the model approach both support a high fractionation of up to -25‰ during nitrification. However, the nitrogen balance and nitrogen stable isotopes suggest that most important processes are remineralization of organic matter to ammonium and further on the oxidation to nitrate. Denitrification and nitrate assimilation play a subordinate role in the Elbe Estuary.

Application of non-lethal stable isotope analysis to assess feeding patterns of juvenile pallid sturgeon Scaphirhynchus albus: a comparison of tissue types and sample preservation methods

USGS Publications Warehouse

Andvik, R.T.; VanDeHey, J.A.; Fincel, M.J.; French, William E.; Bertrand, K.N.; Chipps, Steven R.; Klumb, Robert A.; Graeb, B.D.S.

2010-01-01

Traditional techniques for stable isotope analysis (SIA) generally require sacrificing animals to collect tissue samples; this can be problematic when studying diets of endangered species such as the pallid sturgeon Scaphirhynchus albus. Our objectives were to (i) determine if pectoral fin tissue (non-lethal) could be a substitute for muscle tissue (lethal) in SIA of juvenile pallid sturgeon, and (ii) evaluate the influence of preservation techniques on stable isotope values. In the laboratory, individual juvenile pallid sturgeon were held for up to 186 day and fed chironomids, fish, or a commercially available pellet diet. Significant, positive relationships (r² ≥ 0.8) were observed between fin and muscle tissues for both δ15N and δ13C; in all samples isotopes were enriched in fins compared to muscle tissue. Chironomid and fish based diets of juvenile pallid sturgeon were distinguishable for fast growing fish (0.3 mm day−1) using stable δ15N and δ13C isotopes. Frozen and preserved fin tissue δ15N isotopes were strongly related (r2 = 0.89) but δ13C isotopes were weakly related (r2 = 0.16). Therefore, freezing is recommended for preservation of fin clips to avoid the confounding effect of enrichment by ethanol. This study demonstrates the utility of a non-lethal technique to assess time integrated food habits of juvenile pallid sturgeon and should be applicable to other threatened or endangered species.

Every apple has a voice: using stable isotopes to teach about food sourcing and the water cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oerter, Erik; Malone, Molly; Putman, Annie

Agricultural crops such as fruits take up irrigation and meteoric water and incorporate it into their tissue (fruit water) during growth, and the geographic origin of a fruit may be traced by comparing the H and O stable isotope composition ( δ 2H and δ 18O values) of fruit water to the global geospatial distribution of H and O stable isotopes in precipitation. This connection between common fruits and the global water cycle provides an access point to connect with a variety of demographic groups to educate about isotope hydrology and the water cycle. Within the context of a 1-daymore » outreach activity designed for a wide spectrum of participants (high school students, undergraduate students, high school science teachers) we developed introductory lecture materials, in-class participatory demonstrations of fruit water isotopic measurement in real time, and a computer lab exercise to couple actual fruit water isotope data with open-source online geospatial analysis software. Here, we assessed learning outcomes with pre- and post-tests tied to learning objectives, as well as participant feedback surveys. Results indicate that this outreach activity provided effective lessons on the basics of stable isotope hydrology and the water cycle. But, the computer lab exercise needs to be more specifically tailored to the abilities of each participant group. This pilot study provides a foundation for further development of outreach materials that can effectively engage a range of participant groups in learning about the water cycle and the ways in which humans modify the water cycle through agricultural activity.« less

Trophic level and macronutrient shift effects associated with the weaning process in the Postclassic Maya.

PubMed

Williams, Jocelyn S; White, Christine D; Longstaffe, Fred J

2005-12-01

The weaning process was investigated at two Maya sites dominated by Postclassic remains: Marco Gonzalez (100 BC-AD 1350) and San Pedro (1400-AD 1650), Belize. Bone collagen and bioapatite were analyzed from 67 individuals (n < or = 6 years = 15, n > 6 years = 52). Five isotopic measures were used to reconstruct diet and weaning: stable nitrogen- and carbon-isotope ratios in collagen, stable carbon- and oxygen-isotope ratios in bioapatite, and the difference in stable carbon-isotope values of coexisting collagen and bioapatite. Nitrogen-isotope ratios in infant collagen from both sites are distinct from adult females, indicating a trophic level effect. Collagen-to-bioapatite differences in infant bone from both sites are distinct from adult females, indicating a shift in macronutrients. Oxygen-isotope ratios in infant bioapatite from both sites are also distinct from adult females, indicating the consumption of breast milk. Among infants, carbon- and nitrogen-isotope ratios vary, indicating death during different stages in the weaning process. The ethnohistoric and paleopathological literature on the Maya indicate cessation of breast-feeding between ages 3-4 years. Isotopic data from Marco Gonzalez and San Pedro also indicate an average weaning age of 3-4 years. Based on various isotopic indicators, weaning likely began around age 12 months. This data set is not only important for understanding the weaning process during the Postclassic, but also demonstrates the use of collagen-to-bioapatite spacing as an indicator of macronutrient shifts associated with weaning. 2005 Wiley-Liss, Inc.

Determination of kinetic isotopic fractionation of water during bare soil evaporation

NASA Astrophysics Data System (ADS)

Quade, Maria; Brüggemann, Nicolas; Graf, Alexander; Rothfuss, Youri

2017-04-01

A process-based understanding of the water cycle in the atmosphere is important for improving meteorological and hydrological forecasting models. Usually only net fluxes of evapotranspiration - ET are measured, while land-surface models compute their raw components evaporation -E and transpiration -T. Isotopologues can be used as tracers to partition ET, but this requires knowledge of the isotopic kinetic fractionation factor (αK) which impacts the stable isotopic composition of water pools (e.g., soil and plant waters) during phase change and vapor transport by soil evaporation and plant transpiration. It is defined as a function of the ratio of the transport resistances in air of the less to the most abundant isotopologue. Previous studies determined αK for free evaporating water (Merlivat, 1978) or bare soil evaporation (Braud et al. 2009) at only low temporal resolution. The goal of this study is to provide estimates at higher temporal resolution. We performed a soil evaporation laboratory experiment to determine the αK by applying the Craig and Gordon (1965) model. A 0.7 m high column (0.48 m i.d.) was filled with silt loam (20.1 % sand, 14.9 % loam, 65 % silt) and saturated with water of known isotopic composition. Soil volumetric water content, temperature and the isotopic composition (δ) of the soil water vapor were measured at six different depths. At each depth microporous polypropylene tubing allowed the sampling of soil water vapor and the measurement of its δ in a non-destructive manner with high precision and accuracy as detailed in Rothfuss et al. (2013). In addition, atmospheric water vapor was sampled at seven different heights up to one meter above the surface for isotopic analysis. Results showed that soil and atmospheric δ profiles could be monitored at high temporal and vertical resolutions during the course of the experiment. αK could be calculated by using an inverse modeling approach and the Keeling (1958) plot method at high temporal resolution over a long period. We observed an increasing δ in the evaporating water vapor due to more enriched surface water. This leads to a higher transport resistances and an increasing αK. References Braud, I., Bariac, T., Biron, P., and Vauclin, M.: Isotopic composition of bare soil evaporated water vapor. Part II: Modeling of RUBIC IV experimental results, J. Hydrol., 369, 17-29. Craig, H. et al., 1965. Deuterium and oxygen 18 variations in the ocean and marine atmosphere. In: E. Tongiogi (Editor), Stable Isotopes in Oceanographic Studies and Paleotemperatures. V. Lishi, Spoleto, Italy, pp. 9-130. Keeling, C. D.: The Concentration and Isotopic Abundances of Atmospheric Carbon Dioxide in Rural Areas, Geochim. Cosmochim. Acta, 13, 322-334. Merlivat, L., 1978. Molecular Diffusivities of H216O, HD16O, and H218O in Gases. J Chem Phys, 69, 2864-2871. Rothfuss, Y. et al., 2013. Monitoring water stable isotopic composition in soils using gas-permeable tubing and infrared laser absorption spectroscopy. Water Resour. Res., 49, 1-9.

Biomedical research applications of electromagnetically separated enriched stable isotopes

NASA Astrophysics Data System (ADS)

Lambrecht, R. M.

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

Using 2H and 18O in assessing evaporation and water residence time of lakes in EPA’s National Lakes Assessment.

EPA Science Inventory

Stable isotopes of water and organic material can be very useful in monitoring programs because stable isotopes integrate information about ecological processes and record this information. Most ecological processes of interest for water quality (i.e. denitrification) require si...

CORRESPONDENCE OF STABLE ISOTOPE AND GUT CONTENTS ANALYSES IN DETERMINING TROPHIC POSITION OF STREAM FISHES

EPA Science Inventory

It is generally accepted that both stable isotope analysis (SIA) and gut contents analysis (GCA) be used in food web studies; however, few researchers have analyzed these data in concert. We utilized SIA and GCA to determine if longitudinal and seasonal variation in diet affects...

Comparing trophic position of stream fishes using stable isotope and gut contents analyses

EPA Science Inventory

Stable isotope analysis (SIA) and gut content analysis (GCA) are commonly used in food web studies, but few studies analyze these data in concert. We used SIA and GCA to identify diets and trophic position (TP) of six stream fishes and to compare TP estimates between methods. Ord...

AGGREGATING FOOD SOURCES IN STABLE ISOTOPE DIETARY STUDIES: LUMP IT OR LEAVE IT?

EPA Science Inventory

A common situation when stable isotope mixing models are used to estimate food source dietary contributions is that there are too many sources to allow a unique solution. To resolve this problem one option is to combine sources with similar signatures such that the number of sou...