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1

Natural-abundance stable carbon isotopes of small-subunit ribosomal RNA (SSU rRNA) from Guaymas Basin (Mexico)  

NASA Astrophysics Data System (ADS)

Small-subunit ribosomal RNA (SSU rRNA) is a phylogenetically informative molecule found in all species. Because it is poorly preserved in most environments, it is a useful marker for active microbial populations. We are using the natural-abundance stable carbon isotopic composition of specific microbial groups to help identify the carbon substrates contributing to microbial biomass in a variety of marine environments. At Guaymas Basin, hydrothermal fluids interact with abundant sedimentary organic carbon to produce natural gas and petroleum. Where this reaches the sediment surface, it can support dense patches of seafloor life, including Beggiatoa mats. We report here on the stable carbon isotopic composition of SSU rRNA from a Beggiatoa mat transect, a cold background site, a warm site with high oil concentration, and a second Beggiatoa mat. The central part of the transect mat overlay the steepest temperature gradient, and was visually dominated by orange Beggiatoa. This was fringed by white Beggiatoa mat and bare, but still warm, sediment. Methane concentrations were saturating beneath the orange and white mats and at the oily site, lower beneath bare sediment, and below detection at the background site. Our initial hypotheses were that rRNA isotopic composition would be strongly influenced by methane supply, and that archaeal rRNA might be lighter than bacterial due to contributions from methanogens and anaerobic methane oxidizers. We used biotin-labeled oligonucleotides to capture Bacterial and Archaeal SSU rRNA for isotopic determination. Background-site rRNA was isotopically heaviest, and bacterial RNA from below 2 cm at the oily site was lightest, consistent with control by methane. Within the transect mat, however, the pattern was more complicated; at some sediment depths, rRNA from the mat periphery was isotopically lightest. Part of this may be due to the spatially and temporally variable paths followed by hydrothermal fluid, which can include horizontal flow. There was no consistent isotopic difference between rRNAs captured by the two probes, although RNA recoveries were too low for isotopic determinations at depths where methanogens and methane oxidizers are expected. Our prediction that rRNA stable carbon isotopic composition would correlate with methane supply was borne out by the comparison between background and mat sediments, but may be an oversimplification for sites within hydrothermal features. Future work will include the isotopic characterization of other potential carbon substrates, such as acetate. We are also investigating cold-seep sediments and brine pools in the Gulf of Mexico, where methane is significantly more 13C-depleted than at Guaymas Basin and may therefore leave a stronger imprint on microbial biomass.table carbon isotopes of rRNA captured with Bacterial and Archaeal probes at mat transect and background sites.

MacGregor, B. J.; Mendlovitz, H.; Albert, D.; Teske, A. P.

2012-12-01

2

Stable isotope studies  

SciTech Connect

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

Ishida, T.

1992-01-01

3

Nitrogen and carbon stable isotope abundances support the myco-heterotrophic nature and host-specificity of certain achlorophyllous plants  

Microsoft Academic Search

Summary Over 400 species of achlorophyllous vascular plants are thought to obtain all C from symbiotic fungi. Consequently, they are termed 'myco-heterotrophic.' However, direct evidence of myco-heterotrophy in these plants is limited. During an investigation of the patterns of N and C stable isotopes of various eco- system pools in two old-growth conifer forests, we sampled six species

Steven A. Trudell; Paul T. Rygiewicz; Robert L. Edmonds

2003-01-01

4

Stable-carbon isotope composition of Poaceae pollen: an assessment for reconstructing C3 and C4 grass abundance  

Microsoft Academic Search

Plants using the C3 and C4 photosynthetic pathways differ in carbon-isotope composition, and this difference offers a means to estimate the relative abundance of these two functional groups in the palaeorecord. We report here results of a study aiming to evaluate pollen &dgr;13C(&dgr;13Cp) of Poaceae (the grass family) as a proxy indicator for palaeoecological studies. On average &dgr;13Cp differs by

David M. Nelson; Feng Sheng Hu; Robert H. Michener

2006-01-01

5

Characterizing the Spatial and Temporal Variations in Organic Carbon Abundance and Stable Isotope Ratios in Lake Sediments Containing Evidence of Prehistoric Agriculture  

NASA Astrophysics Data System (ADS)

Intra-basin spatial variability in lake sediments has the potential to limit the utility of interpretations based on the analysis of a single sediment core. We analyzed a network of five sediment cores to assess geochemical and isotopic spatial variability across a lake in southern Costa Rica. Laguna Zoncho (8.813N, 82.963W) provides an excellent opportunity to detect spatial variability because it is a small lake (0.75 ha) with a known history of prehistoric maize agriculture in its watershed. During the agricultural period (1770-570 cal BP) at Zoncho, stable carbon isotope values in the five cores average -23 V-PDB; these values increase to -27 V-PDB during the subsequent period of forest recovery. In prior work at the lake, this forest recovery was assumed to have been initiated by the Spanish Conquest about AD 1500, but our new findings suggest it may have occurred earlier and have been driven by a different set of circumstances. We attribute the more positive values during the agricultural period to a greater abundance of C4 vegetation in the watershed as the result of agricultural activity that removed native C3 forest vegetation and created fields and disturbed environments that favor C4 plants. Organic carbon contents during the agricultural period average 5 % and increase to an average of 16 % post-Conquest. Molar C/N ratios range from 13 during the agricultural period to 16 after the cessation of agriculture in the watershed. The cores may indicate a non-simultaneous end to agriculture in the watershed. Stable carbon isotope values and organic carbon contents in three of the four cores collected closer to shore contain evidence of an abrupt end of agriculture around 1000 cal. BP. In these cores, stable carbon isotope values indicate a dramatic shift from C4 to C3 inputs and a rapid increase in organic contents. The fourth core shows this shift around 700 cal. BP. The core recovered from the center of the lake records a gradual end to agriculture in the watershed from 1000 to 700 cal. BP, suggesting that the central core contains reworked material from refocusing of intra-basinal sediments. Spatial variations in organic carbon content and stable carbon isotopic values in a lake as small as Laguna Zoncho highlights the importance of core site selection.

Taylor, Z. P.; Finkelstein, D. B.; Horn, S. P.

2009-12-01

6

Stable Isotope Enrichment Capabilities at ORNL  

SciTech Connect

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

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

2013-01-01

7

Stable isotope laser spectroscopy  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

8

ISOTOPIC TITANIUM ABUNDANCES IN LOCAL M DWARFS  

SciTech Connect

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

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

2009-07-10

9

STABLE ISOTOPES AND COURTS James R. Ehleringer*  

E-print Network

STANDARDS AND STABLE ISOTOPE RATIO ANALYSIS...........398 A. The Federal Rules and Daubert .................................................................................................411 B. Application of Evidence Rules to Stable Isotope Ratio Analysis ................411 1 .................................................................435 C. DNA Profiling and Stable Isotope Ratio Analysis......................................436 1

Ehleringer, Jim

10

THE ATOMIC WEIGHTS COMMISSION AND ISOTOPIC ABUNDANCE RATIO DETERMINATIONS.  

SciTech Connect

Following Thomson's discovery of stable isotopes in non-radioactive chemical elements, the derivation of atomic weight values from mass spectrometric measurements of isotopic abundance ratios moved very slowly. Forty years later, only 3 1/2 % of the recommended values were based on mass spectrometric measurements and only 38% in the first half century. It might be noted that two chemical elements (tellurium and mercury) are still based on chemical measurements, where the atomic weight value calculated from the relative isotopic abundance measurement either agrees with the value from the chemical measurement or the atomic weight value calculated from the relative isotopic abundance measurement falls within the uncertainty of the chemical measurement of the atomic weight. Of the 19 chemical elements, whose atomic weight is based on non-corrected relative isotopic abundance measurements, five of these are two isotope systems (indium, iridium, lanthanum, lutetium and tantalum) and one is a three-isotope system (oxygen).

HOLDEN, N.E.

2005-08-07

11

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

12

Conditional flux analysis and stable isotopes  

NASA Astrophysics Data System (ADS)

We propose to investigate to what extend conditional flux analysis can benefit from the addition of stable isotope information. Stable isotopes have been recognized for their potential as process tracer, and could add an extra dimension to the conditional flux concept, which aims at directly quantifying component fluxes and identifying their sources. Differences in 13C abundance in carbon dioxide can be used to distinguish assimilation or respiration sources, whereas the 18O abundance expresses differences in water exchange, for instance between canopy and soil. Lending to recent advances in measurement technology, stable isotopes can now be measured at high temporal resolutions (10Hz) required for commonly applied micrometeorological methods such as the eddy-covariance technique, or related conditional flux methods. We will present current ideas on how the conditional flux method, as recently proposed and evaluated by Thomas et al. (2008), Scanlon & Sahu (2008), to perform daytime flux partitioning at the ecosystem level, can be refined by stable isotope analysis (13C and 18O) of carbon dioxide as additional dimension for identification of fluxes.

Zeeman, M. J.; Knohl, A.; Sturm, P.; Buchmann, N. C.; Thomas, C. K.

2009-12-01

13

Teaching stable isotopes  

NSDL National Science Digital Library

This is a reading assignment in three parts, with problem sets for each part. Part 1 is introductory, part 2 explains isotopic effects of volatilization and fluid flow during metamorphism, and part 3 uses data from the Alta contact aureole, Utah, as an example of the processes.

Dunn, Steve

14

Stable isotope studies  

Microsoft Academic Search

The large vapor pressure isotope effect (VPIE) for CH2F2\\/CD2F2 was elucidated through the Gaussian-70 ab initio molecular orbital calculations using the STO-3G basis set. Results correlate well with all observed carbon and hydrogen VPIE's in liquid methane, methyl fluoride, methylene difluoride and fluoroform. The VPIE measurements of (14)NH3, and (14)ND3 were completed. The triple points were 195.5 K, 195.6 K,

T. Ishida

1984-01-01

15

Paleoproxies: Heavy Stable Isotope Perspectives  

NASA Astrophysics Data System (ADS)

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.

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

2002-12-01

16

Stable Carbon and Nitrogen Isotopic  

Microsoft Academic Search

The perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, are part of the coldest and driest ecosystem on earth. To understand lacustrine carbon and nitrogen cycling in this end-member ecosystem, and to define paleolimnological proxies for ice-covered lakes, we measured the stable carbon and nitrogen isotopic composition of particulate organic matter (POM) and benthic organic matter (BOM) within the

Jennifer Lawson; PETER T. DORAN; Fabien Kenig; DAVID J. DES MARAIS; JOHN C. PRISCU

2004-01-01

17

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

USGS Publications Warehouse

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

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

1997-01-01

18

Chlorine stable isotopes in sedimentary systems: does size matter?  

NASA Technical Reports Server (NTRS)

Stable isotope abundances vary because of size differences. The chlorine stable isotope system was one of the first described theoretically, but had a slow, disappointment strewn development, relative to other elements. Method improvement gave only small, but significant, differences in compositions of geological materials. Eventually, brines and groundwater chlorides gave larger differences. Physical processes like diffusion and adsorption, probably are the main controls of groundwater compositions. Recent work on anthropogenic groundwater contaminants shows variations resulting from manufacturing processes; implying possibilities of tracing sources.

Coleman, Max

2004-01-01

19

Assessing the Amazon Basin Circulation with Stable Water Isotopes  

Microsoft Academic Search

The isotopic abundances of Oxygen-18 (delta 18O) and Deuterium (delta D) over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Tracking the two stable but rare isotopes of water (1HD16O and 1H218O) makes it possible to trace Amazonian regional evaporative and condensation processes. This offers isotopic constraints on

K. McGuffie; A. Henderson-Sellers

2004-01-01

20

Aberrant Water Homeostasis Detected by Stable Isotope Shannon P. O'Grady1  

E-print Network

Aberrant Water Homeostasis Detected by Stable Isotope Analysis Shannon P. O'Grady1 *, Adam R. Wende. (2010) Aberrant Water Homeostasis Detected by Stable Isotope Analysis. PLoS ONE 5(7): e11699. doi:10, and disease-related alterations in metabolism, may have on stable isotope ratios at natural abundance levels

Ehleringer, Jim

21

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...

22

Substitution of stable isotopes in Chlorella  

NASA Technical Reports Server (NTRS)

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.

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

1969-01-01

23

Stable Vanadium Isotope Fractionation at High Temperatures  

NASA Astrophysics Data System (ADS)

Vanadium is a redox sensitive transition metal existing in multiple valence states at terrestrial conditions. Stable vanadium isotopes (reported as ?51V in % relative to an Alfa Aesar standard [1]) are a potentially powerful tracer of oxidation-reduction processes. However, the determination of ?51V is analytically challenging, primarily due to the extreme abundance ratio between the only two stable isotopes (51V/50V ~ 400) and, also, significant isobaric interferences of 50Ti and 50Cr on the minor 50V isotope. We have developed the first method able to determine ?51V to a precision (2 s.d. ~ 0.15%, [1,2]) that enables application of this isotope system to geological processes. To usefully investigate high temperature processes using vanadium isotopes, knowledge of the isotope composition and range of values present in the ambient mantle is required. Here we discuss the first ?51V measured in igneous materials encompassing peridotites, MORB, and primitive mantle-derived melts such as picrites. This first dataset provides a preliminary reconnaissance of the magnitude of natural fractionation. We find little isotope fractionation in suites of peridotites and MORB (< 0.5 %). However, the small but analytically significant variation appears to be related to secondary processes, with extremely altered peridotites consistently displaying slightly heavier isotope compositions. We find no resolvable ?51V variation between fresh MORB glass and fresh peridotite. Intriguingly, a suite of subduction-related peridotites from the Mariana forearc, previously characterized for fO2 [3], do not display the predicted co-variation between ?51V and fO2, but instead also have compositions identical to MORB glass. This nominally supports recent indications that there is limited difference in the oxygen fugacity of the MORB source and the subarc mantle wedge [e.g., 4, 5]. Finally, we observe large ?51V variations (~ 2 %) in a suite of evolving lavas from Hekla volcano, Iceland, which produces eruptive material with a wide range of SiO2 from a cogenetic source. The ?51V of Hekla lavas are well correlated with indices of differentiation such as MgO and SiO2, suggesting that processes such as fractional crystallization may be a fundamental cause of high temperature ?51V fractionation. This nascent dataset provides a first glimpse into the magnitude of vanadium isotope fractionation that may be expected at high temperatures. The presence of significant isotope variation outside of analytical precision in these materials bodes well for the use of ?51V to address a variety of broad scale questions in high temperature planetary processes. [1] Nielsen, S.G., Prytulak, J., Halliday, A.N. 2011. Geost. Geoanal. Res., in press. [2] Prytulak, J., Nielsen, S.G., Halliday, A.N. 2011. Geost. Geoanal. Res., in press. [3] Parkinson and Pearce, 1998. Journal of Petrology, 39, 1577-1618. [4] Lee et al., 2005. Journal of Petrology, 46, 2313-2336. [5] Cottrell and Kelley, 2011. Earth and Planetary Sciences Letters, 305, 270-282.

Prytulak, J.; Parkinson, I. J.; Savage, P. S.; Nielsen, S. G.; Halliday, A. N.

2011-12-01

24

Preliminary studies of the impact of excreted N on cycling and uptake of N in pasture systems using natural abundance stable isotopic discrimination  

Microsoft Academic Search

The possibility of using natural abundance techniques to determine N transformations and flows after deposition of cattle dung has been examined. These preliminary results showed that d15N in dung was greater than in plants growing in association with particular pats. This, and other observational information, indicated that dung pats of different ages were being examined. There were significant variations in

S. J. Kerley; S. C. Jarvis

1996-01-01

25

Sourcing drugs with stable isotopes James R. Ehleringer  

E-print Network

and trafficking information. These stable isotope ratio measurements are conducted on an isotope ratioing massSourcing drugs with stable isotopes James R. Ehleringer Stable Isotope Ratio Facility@erols.com Michael J. Lott Stable Isotope Ratio Facility for Environmental Research (SIRFER) Department of Biology

Ehleringer, Jim

26

Applications of stable isotopes in clinical pharmacology  

PubMed Central

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

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

2011-01-01

27

Stable Isotope Ratios: Hurricane Olivia  

Microsoft Academic Search

The oxygen and hydrogen isotopic compositions of rains from HurricaneOlivia (1994) in the eastern Pacific were measured. The rains werecollected on 24 and 25 September during airplane flights conducted at anelevation of 3 km. Hurricane Olivia peaked in intensity to a category-4storm between the two dates. Isotope ratios of rains from HurricaneOlivia were markedly lower (d 18O = 13.9to 28.8)

James R. Lawrence; Stanley David Gedzelman; John Gamache; Michael Black

2002-01-01

28

Bone stable isotope studies in archaeology  

Microsoft Academic Search

Stable isotope ratios of carbon and nitrogen in bone have become increasingly frequent inclusions in archaeological reports over the past few decades. The majority of such studies has been done in North America, where the use of marine foods and the introduction of maize have been monitored. Similar questions have been addressed in Mesoamerica and South America. In Europe, stable

Margaret J. Schoeninger; Katherine Moore

1992-01-01

29

Uncertainty in source partitioning using stable isotopes  

Microsoft Academic Search

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

Donald L. Phillips; Jillian W. Gregg

2001-01-01

30

Stable Isotopes in Dendroclimatology: Moving Beyond Potential  

Microsoft Academic Search

\\u000a When trees grow, they assimilate carbon from atmospheric carbon dioxide, and hydrogen and oxygen from soil water. The stable\\u000a isotope ratios of these three elements carry signals that can be interpreted in terms of past climate because isotope ratios\\u000a are climatically controlled by the trees water and gas exchange budgets. The traditional tree-ring proxies form the most\\u000a widespread and arguably

Mary Gagen; Danny McCarroll; Neil J. Loader; Iain Robertson

31

Estimating Rates of Denudation Using Cosmogenic Isotope Abundances in Sediment  

Microsoft Academic Search

We propose, as a testable hypothesis, a basin-scale approach for interpreting the abundance of in situ produced cosmogenic isotopes, an approach which considers explicitly both the isotope and sediment flux through a drainage basin. Unlike most existing models, which are appropriate for evaluating in situ produced cosmogenic isotope abundance at discrete points on Earth's surface, our model is designed for

Paul Bierman; Eric J. Steig

1996-01-01

32

Abundance of four sulfur mustard-DNA adducts ex vivo and in vivo revealed by simultaneous quantification in stable isotope dilution-ultrahigh performance liquid chromatography-tandem mass spectrometry.  

PubMed

Sulfur mustard (SM) is a highly reactive alkylating vesicant and causes blisters upon contact with skin, eyes, and respiratory organs. It covalently links with DNAs by forming four mono- or cross-link adducts. In this article, the reference standards of SM-DNA adducts and deuterated analogues were first synthesized with simplified procedures containing only one or two steps and using less toxic chemical 2-(2-chloroethylthio)ethanol or nontoxic chemical thiodiglycol as starting materials. A sensitive and high-throughput simultaneous quantification method of N(7)-[2-[(2-hydroxyethyl)thio]-ethyl]guanine (N(7)-HETEG), O(6)-[2-[(2-hydroxyethyl)thio]-ethyl]guanine (O(6)-HETEG), N(3)-[2-[(2-hydroxyethyl)thio]-ethyl]adenine (N(3)-HETEA), and bis[2-(guanin-7-yl)ethyl]sulfide (Bis-G) in the Sprague-Dawley rat derma samples was developed by stable isotope dilution-ultrahigh performance liquid chromatography-tandem mass spectrometry (ID-UPLC-MS/MS) with the aim of revealing the real metabolic behaviors of four adducts. The method was validated, the limit of detection (S/N ratio greater than 10) was 0.01, 0.002, 0.04, and 0.11 fmol on column for N(7)-HETEG, O(6)-HETEG, Bis-G, and N(3)-HETEA, respectively, and the lower limit of quantification (S/N ratio greater than 20) was 0.04, 0.01, 0.12, and 0.33 fmol on column for N(7)-HETEG, O(6)-HETEG, Bis-G, and N(3)-HETEA, respectively. The accuracy of this method was determined to be 76% to 129% (n = 3), and both the interday (n = 6) and intraday (n = 7) precisions were less than 10%. The method was further applied for the quantifications of four adducts in the derma of adult male Sprague-Dawley rats exposed to SM ex vivo and in vivo, and all adducts had time- and dose-effect relationships. To the best of our knowledge, this is the first time that the real presented status of four DNA adducts was simultaneously revealed by the MS-based method, in which Bis-G showed much higher abundance than the result previously reported and N(3)-HETEA showed much less. It should be noted that since the interstrand cross-linked adduct is believed to stall DNA replication and finally induce a double-strand break, the higher abundance of Bis-G is a great indication of a more serious DNA lesion by SM alkylation. PMID:24467472

Yue, Lijun; Wei, Yuxia; Chen, Jia; Shi, Huiqin; Liu, Qin; Zhang, Yajiao; He, Jun; Guo, Lei; Zhang, Tingfen; Xie, Jianwei; Peng, Shuangqing

2014-04-21

33

Stable strontium isotope fractionation in synthetic barite  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

34

Production of stable isotopes utilizing the plasma separation process  

NASA Astrophysics Data System (ADS)

A plasma separation process (PSP) is being operated at Theragenics Corporation's , Oak Ridge, TN, facility for the enrichment of stable isotopes. The PSP utilizes ion cyclotron mass discrimination to separate isotopes on a relatively large scale. With a few exceptions, nearly any metallic element could be processed with PSP. Output isotope enrichment factor depends on natural abundance and mass separation and can be fairly high in some cases. The Theragenics PSP facility is believed to be the only such process currently in operation. This system was developed and formerly operated under the US Department of Energy Advanced Isotope Separation program. Theragenics also has a laboratory at the PSP site capable of harvesting the isotopes from the process and a mass spectrometer system for analyzing enrichment and product purity. Since becoming operational in 2002, Theragenics has utilized the PSP to separate isotopes of several elements including: dysprosium, erbium, gadolinium, molybdenum and nickel. Currently, Theragenics is using the PSP for the separation of 102Pd, which is used as precursor for the production of 103Pd. The 103Pd radioisotope is the active ingredient in TheraSeed , which is used in the treatment of early stage prostate cancer and being investigated for other medical applications. New industrial, medical and research applications are being investigated for isotopes that can be enriched on the PSP. Pre-enrichment of accelerator or reactor targets offers improved radioisotope production. Theragenics operates 14 cyclotrons for proton activation and has access to HFIR at ORNL for neutron activation of radioisotopes.

Bigelow, T. S.; Tarallo, F. J.; Stevenson, N. R.

2005-12-01

35

Stable isotope enrichment using a plasma centrifuge  

NASA Astrophysics Data System (ADS)

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

Krishnan, Mahadevan; Bures, Brian; Madden, Robert

2012-10-01

36

Quantifying intrapopulation variability in stable isotope data for Spotted Seatrout  

E-print Network

stable isotope (SI) analysis, have been widely ap- plied to fish populations as a method111 Quantifying intrapopulation variability in stable isotope data for Spotted Seatrout (Cynoscion of the National Marine Fisheries Service, NOAA. Abstract--Stable isotope (SI) values of carbon (13C) and nitrogen

37

Stable Isotopes Confirm Community Patterns in Foraging Among Hawaiian Procellariiformes  

E-print Network

, Ontario, K7L 3N6, Canada *Corresponding author; E-mail: mgreg@sun.ac.za Abstract.--Stable-isotope analysis was to compare community foraging patterns as determined by stable-isotope analysis with tradi- tional studies50 Stable Isotopes Confirm Community Patterns in Foraging Among Hawaiian Procellariiformes

Jones, Ian L.

38

Paleoenvironmental reconstruction of the Asbole fauna (Busidima Formation, Afar, Ethiopia) using stable isotopes  

Microsoft Academic Search

The Middle Pleistocene environmental and climatic conditions at Asbole, lower Awash Valley, Ethiopia were reconstructed using stable carbon and oxygen isotopic composition (13C, 18O) of fossil tooth enamel coupled with faunal abundance data. We analyzed the isotopic composition of a total of 80 herbivorous tooth enamel samples from 15 mammalian taxa, which archive the dietary preferences and drinking behavior from

Zelalem Bedaso; Jonathan G. Wynn; Zeresenay Alemseged; Denis Geraads

2010-01-01

39

Characterising the Terrestrial Stable Cr Isotope Cycle  

NASA Astrophysics Data System (ADS)

Cr isotopes were shown to present a sensitive tracer of redox changes in aqueous solutions [1,2]. Here, the potential of stable Cr isotope fractionation in the environment was further investigated by high-precision double- spike MC-ICP-MS measurements. Reduction experiments of Cr(VI) to Cr(III) in aqueous solutions on ion exchange columns confirmed the mass-dependent Cr isotope fractionation of -3.4 per atomic mass unit reported by Ellis et al. [1]. Furthermore, these experiments revealed that the fractionation associated with adsorption is minor. This is shown by a very small preferential adsorption of isotopically heavy chromium of most likely Cr(III) species on the anion resin. A similar observation was made for Cr(III) species on cation resin. This is in line with the negligible fractionation effects that have been reported for adsorption of Cr(VI) onto ?-Al2O3 and goethite surfaces [2], respectively. Thus, the large Cr isotope fractionation that accompanies Cr reduction and the small sorption effects of both Cr(VI) and Cr(III) species make stable Cr isotopes a sensitive tracer to detect and quantify redox changes in a variety of geochemical reservoirs. The stable Cr isotope compositions of the principle silicic igneous reservoirs of the Earth do not show measurable variations. ?^{53}Cr/^{52}Cr values (relative to SRM3112a) of six mantle lherzolites (- 0.0140.083; 2 SD), six ultramafic cumulate rocks (-0.0340.094) and five continental and oceanic basalts that represent partial mantle melts (-0.0440.089) are indistinguishable within uncertainties. Thus, unlike as was suggested for Fe isotopes [3], partial mantle melting appears not to fractionate Cr isotopes. Cr(III)-bearing uvarovite and fuchsite minerals from amphibolite facies metamorphic rocks are also equal to those of igneous rock reservoirs. These observations are not unexpected, because there is no apparent redox change of Cr involved during partial mantle melting or metamorphism. Also the fractionation effects caused by potential ligand changes of Cr between solids, and solids and melt are too small to be detected at high-temperatures. Large Cr isotope fractionations with ?^{53}Cr/^{52}Cr values of +0.672 to +1.093 were observed for crocoite (PbCr(VI)O4), a mineral that forms in oxidising zones of medium- to high- temperature hydrothermal systems. It has yet to be investigated whether Cr isotopes fractionate during the oxidation of Cr(III) to Cr(VI). It is, however, likely, that Cr behaves like its chemical twin Se that only fractionates during reduction [4]. In this case the observed heavy Cr isotope compositions of crocoites are the result of partial Cr(VI) reduction from the hydrothermal fluid, allowing to quantify changes in redox conditions along the hydrothermal pathway. [1] Ellis, A.S. et al. (2002), Science 295, 2060-2062, [2] Ellis, A.S. et al. (2004), Eniron. Sci. Technol. 38, 3604-3607, [3] Weyer, S. et al. (2005), Earth and Planet. Sci. Letters 240, 251-264, [4] Johnson, T.M. and Bullen, T.D. (2004), Reviews in Mineralogy & Geochemistry 55, 289-317.

Schoenberg, R.; Zink, S.; Staubwasser, M.; von Blanckenburg, F.

2006-12-01

40

Stable isotopic analyses in paleoclimatic reconstruction  

SciTech Connect

Most traditional paleoclimatic proxy data have inherent time lags between climatic input and system response that constrain their use in accurate reconstruction of paleoclimate chronology, scaling of its variability, and the elucidation of the processes that determine its impact on the biotic and abiotic environment. With the exception of dendroclimatology, and studies of short-lived organisms and pollen recovered from annually varved lacustrine sediments, significant periods of time ranging from years, to centuries, to millennia may intervene between climate change and its first manifestation in paleoclimatic proxy data records. Reconstruction of past climate through changes in plant community composition derived from pollen sequences and plant remains from ancient woodrat middens, wet environments and dry caves all suffer from these lags. However, stable isotopic analyses can provide more immediate indication of biotic response to climate change. Evidence of past physiological response of organisms to changes in effective precipitation as climate varies can be provided by analyses of the stable isotopic content of plant macrofossils from various contexts. These analyses consider variation in the stable isotopic (hydrogen, oxygen and carbon) content of plant tissues as it reflects (1) past global or local temperature through changes in meteoric (rainfall) water chemistry in the case of the first two isotopes, and (2) plant stress through changes in plant respiration/transpiration processes under differing water availability, and varying atmospheric CO, composition (which itself may actually be a net result of biotic response to climate change). Studies currently being conducted in the Intermountain West indicate both long- and short-term responses that when calibrated with modem analogue studies have the potential of revealing not only the timing of climate events, but their direction, magnitude and rapidity.

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

1995-09-01

41

A large area experiment to determine cosmic ray isotopic abundances  

NASA Technical Reports Server (NTRS)

Measurements of the isotopic composition of cosmic rays have shown that the cosmic ray isotope ratios, Ne-22/Ne-20 and (Mg-25 + Mg-26)/Mg-24, exceed the solar abundance ratios by factors of 2.7 and 1.8, respectively. There are several processes which could be responsible for the observed excess of neutron-rich isotopes. The considered models imply neutron enrichment in the case of other, less abundant species, and a measurement of the involved isotopic abundances could provide a basis for the determination of the dominating processes occurring in cosmic ray sources. However, an experiment utilizing special equipment is necessary to conduct the required measurements. Such an experiment, the Aluminum Isotopic Composition Experiment (Alice), is being designed in a joint effort involving NASA and a West German university. Alice uses a Cherenkov-range technique to determine the isotopic composition of elements from oxygen through argon.

Mauger, B. G.; Balasubrahmanyan, V. K.; Ormes, J. F.; Streitmatter, R. E.; Heinrich, W.; Simon, M.; Tittel, H. O.

1983-01-01

42

The abundances of elements and isotopes in the solar wind  

NASA Technical Reports Server (NTRS)

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

Gloeckler, George; Geiss, Johannes

1988-01-01

43

[Stable isotopes of carbon and nitrogen in soil ecological studies].  

PubMed

The development of stable isotope techniques is one of the main methodological advances in ecology of the last decades of the 20th century. Many biogeochemical processes are accompanied by changes in the ratio between stable isotopes of carbon and nitrogen (12C/13C and 14N/15N), which allows different ecosystem components and different ecosystems to be distinguished by their isotopic composition. Analysis of isotopic composition makes it possible to trace matter and energy flows through biological systems and to evaluate the rate of many ecological processes. The main concepts and methods of stable isotope ecology and patterns of stable isotope fractionation during organic matter decomposition are considered with special emphasis on the fractionation of isotopes in food chains and the use of stable isotope studies of trophic relationships between soil animals in the field. PMID:17966909

Tiunov, A V

2007-01-01

44

Quantitative proteomics using reductive dimethylation for stable isotope labeling.  

PubMed

Stable isotope labeling of peptides by reductive dimethylation (ReDi labeling) is a method to accurately quantify protein expression differences between samples using mass spectrometry. ReDi labeling is performed using either regular (light) or deuterated (heavy) forms of formaldehyde and sodium cyanoborohydride to add two methyl groups to each free amine. Here we demonstrate a robust protocol for ReDi labeling and quantitative comparison of complex protein mixtures. Protein samples for comparison are digested into peptides, labeled to carry either light or heavy methyl tags, mixed, and co-analyzed by LC-MS/MS. Relative protein abundances are quantified by comparing the ion chromatogram peak areas of heavy and light labeled versions of the constituent peptide extracted from the full MS spectra. The method described here includes sample preparation by reversed-phase solid phase extraction, on-column ReDi labeling of peptides, peptide fractionation by basic pH reversed-phase (BPRP) chromatography, and StageTip peptide purification. We discuss advantages and limitations of ReDi labeling with respect to other methods for stable isotope incorporation. We highlight novel applications using ReDi labeling as a fast, inexpensive, and accurate method to compare protein abundances in nearly any type of sample. PMID:25045933

Tolonen, Andrew C; Haas, Wilhelm

2014-01-01

45

Stable isotopes as one of nature's ecological recorders  

E-print Network

of the natural variation in stable isotopes of components of ecological systems have provided new insights ecological activi- ties. Among the many examples, carbon isotope ratios (d13 C) of plant organic matterStable isotopes as one of nature's ecological recorders Jason B. West1 , Gabriel J. Bowen2 , Thure

Ehleringer, Jim

46

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...

47

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

SciTech Connect

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

Spielmann, H.; Nau, H.

1986-07-01

48

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

E-print Network

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

Newman, Michael C.

49

The Stable Isotopic Composition of Atmospheric CO2  

NASA Astrophysics Data System (ADS)

When a bean leaf was sealed in a closed chamber under a lamp (Rooney, 1988), in two hours the atmospheric CO2 in the microcosm reached an isotopic steady state with a 13C abundance astonishingly similar to the global mean value of atmospheric CO2 at that time (-7.5 in the ?13C notation introduced below). Almost concurrently, another research group sealed a suspension of asparagus cells in a different type of microcosm in which within about two hours the atmospheric O2 reached an isotopic steady state with 18O enrichment relative to water in the microcosm that was, too, remarkably similar to the global-scale offset between atmospheric O2 and mean ocean water (21 versus 23.5 in the ?18O notation introduced below; Guy et al., 1987). These classic experiments capture some of the foundations underlying the isotopic composition of atmospheric CO2 and O2. First, in both cases the biological system rapidly imposed a unique isotopic value on the microcosms' atmosphere via their massive photosynthetic and respiratory exchange of CO2 and O2. Second, in both cases the biological system acted on materials with isotopic signals previously formed by the global carbon and hydrological cycles. That is, the bean leaf introduced its previously formed organic matter (the source of the CO2 respired into microcosm's atmosphere), and the asparagus cells were introduced complete with local tap water (from which photosynthesis released molecular oxygen). Therefore, while the isotopic composition of the biological system used was slave to long-term processes, intense metabolic processes centered on few specific enzymes (Yakir, 2002) dictated the short-term atmospheric composition.In a similar vein, on geological timescales of millions of years, the atmosphere and its isotopic composition are integral parts of essentially a single dynamic ocean-atmosphere-biosphere system. This dynamic system exchanges material, such as carbon and oxygen, with the sediments and the lithosphere via slow processes that roughly follow the cycle of: weathering of rock and carbon uptake from the atmosphere, transport to the ocean, sedimentation, plate tectonics, metamorphism, and volcanism - leading to carbon release back to the atmosphere. But on a shorter timescale of years to millennia, the very slow geological processes retreat to the background, against which other massive fluxes control the rapid exchange of carbon and oxygen within the ocean-atmosphere-biosphere system. It is this timescale that is relevant to the well-being of our human society, and is a major focus in much of the research on the carbon cycle.Isotopes were discovered in 1911 (Urey, 1948) and the implications of isotopic substitution in chemical reactions were realized sometime later ( Bigeleisen, 1965). In practice, the use of stable isotopes in geochemistry and biogeochemistry (e.g., Craig, 1953, 1954) awaited the development of the isotope ratio mass spectrometer ( McKinney et al., 1950; Nier, 1947) that provided the necessary precision. Over the 50 years following this breakthrough, the application of stable isotopes has made tremendous progress in the scope of applications, as well as in the resolution and precision of the measurements. The carbon isotopic composition of rocks and sediments was measured intensively since the early 1950s ( Hoefs, 1987). Isotope hydrology caught up quickly ( Clark and Fritz, 1997), followed by the application of stable isotopes in biology and ecology ( Rundel et al., 1988; Griffiths, 1998; Ehleringer et al., 1992). Today, stable isotope measurements have become an indispensable and integral part of atmospheric measurement programs (e.g., Francey et al., 2001; Masarie et al., 2001; Trolier et al., 1996). Efforts to develop analytical and numerical models that incorporate the cycling of stable isotopes in CO2 expanded in parallel (e.g., Bolin, 1981; Ciais et al., 1997a, b; Enting et al., 1995). Recently, the consideration of mass-independent isotope phenomena in nature ( Thiemens, 1999; see Chapter 4.06, and of triple stable isotopes in geochemistry

Yakir, D.

2003-12-01

50

Lithium Isotopic Abundances in Metal-poor Halo Stars  

Microsoft Academic Search

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

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

2006-01-01

51

Assessing the Amazon Basin Circulation with Stable Water Isotopes  

NASA Astrophysics Data System (ADS)

The isotopic abundances of Oxygen-18 (? 18O) and Deuterium (? D) over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Tracking the two stable but rare isotopes of water (1HD16O and 1H218O) makes it possible to trace Amazonian regional evaporative and condensation processes. This offers isotopic constraints on regional to global-scale atmospheric moisture budgets. Based on data in the Global Network on Isotopes in Precipitation (GNIP) database, we analyse the simulation of the land surface hydrology and water cycling. Temporal changes between 1965 and 2000 in stable water isotopic signatures in the Amazon have been used to evaluate global climate model (GCM) predictions revealing notable anomalies. For example, the differences in the wet season deuterium excess between Belem and Manaus are consistent with recent GCM simulations only if there has been a relative increase in evaporation from non-fractionating water sources over this period. Despite earlier predictions that land-use change signals would be found, late twentieth century data reveal no significant change in dry season isotopic characteristics. On the other hand, more recent isotopic data do show trends at stations in the Andes, where as much as 88% of the rainfall is thought to be derived from recycled moisture. At Izobamba the wet season depletions are enhanced (greater depletion) and the dry season ones decreased (less depletion). At Bogota only the wet months show statistically significant changes - also an enhancement. More depletion in the wet months is consistent with reductions in non-fractioning recycling such as through transpiration and in full re-evaporation of canopy-intercepted rainfall. These data might be linked to deforestation impacts. Results of GCM and simpler model simulations of the Amazon suggest that the recent stable isotope record is consistent with the predicted effects of forest removal, perhaps combined with greenhouse warming. At a minimum, large-scale simulations of South American climate ought to be tested against these isotopic data in any validation effort. Specific caveats our conclusions include: (i)monthly isotope data only are available in GNIP and hence analysed; (ii) the statistically significant seasonal changes reported might be related to, or even exaggerated by, El Nio-Southern Oscillation (ENSO) events or other climatic variations that modify the Walker circulation and Inter-Tropical Convergence Zone (ITCZ) position and hence affect the moisture climatology of the Amazon; (iii)no information on fluxes from simulated open water as a surface type in the Amazon GCM experiments has been considered; (iv)the selected models are failing to correctly simulate the relative components of transpiration and re-evaporated canopy interception in the Amazon dry season; and (v) no isotope tracking in the Amazon deforestation simulations was reviewed, because none is yet available. These shortcomings deserve further work.

McGuffie, K.; Henderson-Sellers, A.

2004-05-01

52

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

E-print Network

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

Pachucki, Krzysztof

53

Stable isotope analysis of breath using the optogalvanic effect  

Microsoft Academic Search

A new technique based on the optogalvanic effect has been developed for the measurement of stable isotope ratios in the carbon dioxide of exhaled breath. Data obtained before and after ingestion of harmless stable isotope labeled compounds, metabolized to carbon dioxide, can be used for sensitive noninvasive diagnostics of various disease conditions. The technique uses the specificity of laser resonance

Daniel E. Murnick; M. J. Colgan; H. P. Lie; D. Stoneback

1996-01-01

54

APPROACHES FOR MEASURING STABLE CARBON AND NITROGEN ISOTOPES IN BACTERIA  

EPA Science Inventory

Stable isotopes have been used successfully over the past three decades to trace through aquatic food chairs. his technique, however, has only recently been used to examine aquatic microbial roles in elemental cycling. he major obstacle to measuring stable isotope compositions in...

55

Mercury Elemental and Isotopic Abundances in Mercury-Manganese Stars  

NASA Astrophysics Data System (ADS)

Hg II abundances have been determined for 42 mercury-manganese (HgMn) stars by fitting synthetic spectra to observed spectra of the 3984 A Hg II line. Nine of the stars had lines sharp enough to allow their Hg isotopic abundance mixes to be found. The Hg abundance is reported for more HgMn stars here than in any other single work. No correlation was found between Hg II abundance and Teff or the central wavelength of the 3984 A line. There may be a weak correlation between logg and the derived Hg II abundance. The mean central wavelength of the 3984 A line, an indicator of the Hg isotopic mix, is loosely correlated with T eff: stars with primarily heavy Hg isotopes tend to be cooler. I find that there is no evidence that any of the HgMn stars have 196Hg or 198Hg. For the sharp-lined stars, the 204Hg abundance decreases with increasing T eff. No correlation is seen between mean central wavelength and logg or between vsini and A(Hg) or the central wavelength of the 3984 A line. The 4358 A Hg I line was measured at high spectral resolution for seven HgMn stars. The isotopic shifts are too small and the hyperfine components are too weak to allow unambiguous isotopic abundance ratios to be found. Hg I abundances match Hg II abundances fairly well. Some Hg isotopic mixtures are difficult to explain using only diffusion. HR 7245 has approximately equal abundances of 199Hg, 200Hg, 202Hg, and 204Hg but very little 201Hg and 11 Per has Hg that is mostly 199Hg and 204Hg. My calculations show that the effect of hyperfine splitting of the 201Hg line on diffusion may partly explain the Hg isotopic mix found in HR 7245, but I found no explanation for that of 11 Per. These were the first very high resolution measurements of the 3984 A line for HR 7245 and 11 Per. Although diffusion may be acting in HgMn stars, there must be one or more other mechanisms acting to produce the abundances seen, or our understanding of diffusion is lacking on some important point.

Woolf, Vincent Martell

1998-10-01

56

Tritium and stable isotopes of magmatic waters  

NASA Astrophysics Data System (ADS)

To investigate the isotopic composition and age of water in volcanic gases and magmas, we analyzed samples from 11 active volcanoes ranging in composition from tholeiitic basalt to rhyolite: Mount St. Helens (USA), Kilauea (USA), Pacaya (Guatemala), Galeras (Colombia), Satsuma Iwo-Jima (Japan), Sierra Negra and Alcedo (Ecuador), Vulcano (Italy), Par?cutin (Mexico), Kudryavy (Russia), and White Island (New Zealand). Tritium at relatively low levels (0.1-5 T.U.) is found in most emissions from high-temperature volcanic fumaroles sampled, even at discharge temperatures >700C. Although magmatic fluids sampled from these emissions usually contain high CO 2, S total, HCl, HF, B, Br, 3He R/ RA, and low contents of air components, stable isotope and tritium relations of nearly all such fluids show mixing of magmatic volatiles with relatively young meteoric water (model ages?75 y). Linear ?D/ ?18O and 3H/ ?18O mixing trends of these two end-members are invariably detected at arc volcanoes. Tritium is also detected in fumarole condensates at hot spot basalt volcanoes, but collecting samples approaching the composition of end-member magmatic fluid is exceedingly difficult. In situ production of 3H, mostly from spontaneous fission of 238U in magmas is calculated to be <0.001 T.U., except for the most evolved compositions (high U, Th, and Li and low H 2O contents). These values are below the detection limit of 3H by conventional analytical techniques (about 0.01 T.U. at best). We found no conclusive evidence that natural fusion in the Earth produces anomalous amounts of detectable 3H (>0.05 T.U.).

Goff, F.; McMurtry, G. M.

2000-04-01

57

Some isotopic abundances in the cosmic radiation  

NASA Technical Reports Server (NTRS)

Cosmic ray nuclei with Z not less than 10 have been observed in a detector which measures charge with a double scintillator-Cherenkov array and mass by combining the Cherenkov signal with residual range measured in nuclear emulsions. Results are presented for the isotopic analyses of Al, Ca, Sc, Mn, Fe, Co, Ni and Cu in the energy range 300-800 MeV/amu.

Young, J. S.; Freier, P. S.; Waddington, C. J.

1980-01-01

58

Stable Isotopes of Cr and Se as Tracers of Redox Processes in Earth Surface Environments  

Microsoft Academic Search

\\u000a Redox reactions play a central role in the environmental geochemistry of chromium (Cr) and selenium (Se). A small but growing\\u000a body of research shows that the stable isotope abundances of both elements are altered by these redox reactions. As is observed\\u000a with nitrate and sulfate, reduction of the higher valence oxoanions to lower valence forms induces isotopic fractionation,\\u000a with the

Thomas M. Johnson

59

Does avian malaria infection affect feather stable isotope signatures?  

Microsoft Academic Search

It is widely accepted that stable isotope ratios in inert tissues such as feather keratin reflect the dietary isotopic signature\\u000a at the time of the tissue synthesis. However, some elements such as stable nitrogen isotopes can be affected by individual\\u000a physiological state and nutritional stress. Using malaria infection experiment protocols, we estimated the possible effect\\u000a of malaria parasite infections on

Elizabeth Yohannes; Vaidas Palinauskas; Gediminas Valki?nas; Raymond W. Lee; Casimir V. Bolshakov; Staffan Bensch

60

The use of stable isotopes to study ecosystem gas exchange  

Microsoft Academic Search

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

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

2000-01-01

61

Use of stable isotopes in mineral nutrition research  

SciTech Connect

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

Turnlund, J.R.

1989-01-01

62

Stable Isotope Database: present and past archives  

NASA Astrophysics Data System (ADS)

Paleoclimate data provide benchmarks against which the realism of the processes simulated by climate models can be assessed. Within this framework, it is essential to avoid introducing uncertainties associated with transfer functions and therefore to operate with robust proxies. The implementation of stable isotopes of water or carbon inside climate models motivates a synthesis of available data. Supported by the LABEX L-IPSL and involving a team of climate modelers and paleoclimatologists, this project aims to establish a worldwide database of ?18O, ?D ?17O and ?13C from oceanic microfossils, corals, ice cores, cave speleothems, lakes, tree rings, and vegetation leaves wax. The aim is to provide a global vision of the hydrological cycle during the LGM and other selected key periods (last 2000 years, Mid-Holocene, Dansgaard-Oeschger events, and the Eemian). It requires screening through hundreds of published oceanic and continental records, validating the selection of the data based on resolution and chronological information. We extracted ~900 dated ?18O records from 650 marine sediment cores, 65 ?18O records from 50 ice cores, ~200 ?18O speleothems records from 60 caves, and 540 ?13C records from 290 marine sediment cores. An additional aspect of this project consists in the construction of an online portal providing an intuitive and interactive platform allowing selecting, visualizing, and downloading of the records included in this database, thus improving the distribution and comparison of paleoclimatic records from various sites.

Bolliet, Timoth

2014-05-01

63

Literature survey of isotopic abundance data for 1987-1989  

SciTech Connect

I have compiled all of the data on isotopic abundance measurements and their variation in nature for the time period since the last General Assembly. Most of the data deals with the variations in the abundances as given by per mil deviations from some standard. As such, they are not of major interest to the Atomic Weights Commission. However, there were some measurements which are of general interest in this list.

Holden, N.E. (Brookhaven National Lab., Upton, NY (USA))

1989-08-09

64

Stable isotope views on ecosystem function: challenging or challenged?  

PubMed Central

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, beda, 1822 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

Resco, Victor; Querejeta, Jose I.; Ogle, Kiona; Voltas, Jordi; Sebastia, Maria-Teresa; Serrano-Ortiz, Penelope; Linares, Juan C.; Moreno-Gutierrez, Cristina; Herrero, Asier; Carreira, Jose A.; Torres-Canabate, Patricia; Valladares, Fernando

2010-01-01

65

Continuous operation of spectroscopy instruments for stable isotope analysis  

NASA Astrophysics Data System (ADS)

Routine Application of Novel Stable Isotope Spectroscopy Instruments; Berkeley, California, 12 December 2010 ; Stable isotopes provide a tracer for biogeochemical processes and for exchange between the biosphere and atmosphere at local to global scales. Recent developments in laser spectroscopy now offer the ability to measure stable isotopes in small molecules such as water vapor and carbon dioxide in unprecedented temporal resolution (up to 10 hertz). In a meeting organized with support from the U.S. National Science Foundation-funded Biogeosphere-Atmosphere Stable Isotope Network (BASIN), an international group consisting of researchers and manufacturers' representatives discussed the challenges of daily use of absorption spectroscopy instruments for stable isotope analysis in continuous field operation. Technological advancement in absorption spectroscopy analysis techniques tied to increased availability of affordable instruments has opened the door to new scientific opportunities and facilitates the use of stable isotope analysis by a larger group of researchers. Despite technological progress, though, stable isotope analysis still requires delicate treatment of samples and setup. Meeting participants tried to identify the key responsibilities for individual labs and the scientific community to help ensure comparability of results and prepare for future regional to global collaborative research efforts. The meeting was concluded with the recommendations below.

Zeeman, Matthias J.; Tu, Kevin P.; Knohl, Alexander

2011-06-01

66

Metal stable isotopes in low-temperature systems: A primer  

USGS Publications Warehouse

Recent advances in mass spectrometry have allowed isotope scientists to precisely determine stable isotope variations in the metallic elements. Biologically infl uenced and truly inorganic isotope fractionation processes have been demonstrated over the mass range of metals. This Elements issue provides an overview of the application of metal stable isotopes to low-temperature systems, which extend across the borders of several science disciplines: geology, hydrology, biology, environmental science, and biomedicine. Information on instrumentation, fractionation processes, data-reporting terminology, and reference materials presented here will help the reader to better understand this rapidly evolving field.

Bullen, T.D.; Eisenhauer, A.

2009-01-01

67

18O Stable Isotope Labeling in MS-based Proteomics  

PubMed Central

A variety of stable isotope labeling techniques have been developed and used in mass spectrometry (MS)-based proteomics, primarily for relative quantitation of changes in protein abundances between two compared samples, but also for qualitative characterization of differentially labeled proteomes. Differential 16O/18O coding relies on the 18O exchange that takes place at the C-terminal carboxyl group of proteolytic fragments, where two 16O atoms are typically replaced by two 18O atoms by enzyme-catalyzed oxygen-exchange in the presence of H218O. The resulting mass shift between differentially labeled peptide ions permits identification, characterization and quantitation of proteins from which the peptides are proteolytically generated. This review focuses on the utility of 16O/18O labeling within the context of mass spectrometry-based proteome research. Different strategies employing 16O/18O are examined in the context of global comparative proteome profiling, targeted subcellular proteomics, analysis of post-translational modifications and biomarker discovery. Also discussed are analytical issues related to this technique, including variable 18O exchange along with advantages and disadvantages of 16O/18O labeling in comparison with other isotope-coding techniques. PMID:19151093

Ye, Xiaoying; Luke, Brian; Andresson, Thorkell

2009-01-01

68

Applications of stable isotope analysis in mammalian ecology.  

PubMed

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. PMID:25013986

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

2014-01-01

69

Miniature Laser Spectrometer for Stable Isotope Measurements  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

70

A biomarker based on the stable isotopes of nickel  

PubMed Central

The new stable isotope systems of transition metals are increasingly used to understand and quantify the impact of primitive microbial metabolisms on the modern and ancient Earth. To date, little effort has been expended on nickel (Ni) isotopes but there are good reasons to believe that this system may be more straightforward, and useful in this respect, than some others. Here, we present Ni stable isotope data for abiotic terrestrial samples and pure cultures of methanogens. The dataset for rocks reveals little isotopic variability and provides a lithologic baseline for terrestrial Ni isotope studies. In contrast, methanogens assimilate the light isotopes, yielding residual media with a complementary heavy isotopic enrichment. Methanogenesis may have evolved during or before the Archean, when methane could have been key to Earth's early systems. Our data suggest significant potential in Ni stable isotopes for identifying and quantifying methanogenesis on the early planet. Additionally, Ni stable isotope fractionation may well prove to be the fundamental unambiguous trace metal biomarker for methanogens. PMID:19553218

Cameron, Vyllinniskii; Vance, Derek; Archer, Corey; House, Christopher H.

2009-01-01

71

A biomarker based on the stable isotopes of nickel.  

PubMed

The new stable isotope systems of transition metals are increasingly used to understand and quantify the impact of primitive microbial metabolisms on the modern and ancient Earth. To date, little effort has been expended on nickel (Ni) isotopes but there are good reasons to believe that this system may be more straightforward, and useful in this respect, than some others. Here, we present Ni stable isotope data for abiotic terrestrial samples and pure cultures of methanogens. The dataset for rocks reveals little isotopic variability and provides a lithologic baseline for terrestrial Ni isotope studies. In contrast, methanogens assimilate the light isotopes, yielding residual media with a complementary heavy isotopic enrichment. Methanogenesis may have evolved during or before the Archean, when methane could have been key to Earth's early systems. Our data suggest significant potential in Ni stable isotopes for identifying and quantifying methanogenesis on the early planet. Additionally, Ni stable isotope fractionation may well prove to be the fundamental unambiguous trace metal biomarker for methanogens. PMID:19553218

Cameron, Vyllinniskii; Vance, Derek; Archer, Corey; House, Christopher H

2009-07-01

72

Stable isotope analysis of fatty acids by gas chromatographyisotope ratio mass spectrometry  

Microsoft Academic Search

Compound-specific isotope analysis (CSIA) of fatty acids is a relatively young analytical method. However, CSIA of fatty acids has increasingly become the method of choice in areas where accurate and precise knowledge of isotopic composition at natural abundance level is important. CSIA of fatty acids at natural abundance level provides information on biogenetic and geographic origin of lipids and oils

Wolfram Meier-Augenstein

2002-01-01

73

Multivariate Stable Isotope Analysis to Determine Linkages between Benzocaine Seizures  

NASA Astrophysics Data System (ADS)

In July 2010, a woman was jailed for nine years in the UK after the prosecution successfully argued that attempting to import a cutting agent was proof of involvement in a conspiracy to supply Cocaine. That landmark ruling provided law enforcement agencies with much greater scope to tackle those involved in this aspect of the drug trade, specifically targeting those importing the likes of benzocaine or lidocaine. Huge quantities of these compounds are imported into the UK and between May and August 2010, four shipments of Benzocaine amounting to more then 4 tons had been seized as part of Operation Kitley, a joint initiative between the UK Border Agency and the Serious Organised Crime Agency (SOCA). By diluting cocaine, traffickers can make it go a lot further for very little cost, leading to huge profits. In recent years, dealers have moved away from inert substances, like sugar and baby milk powder, in favour of active pharmaceutical ingredients (APIs), including anaesthetics like Benzocaine and Lidocaine. Both these mimic the numbing effect of cocaine, and resemble it closely in colour, texture and some chemical behaviours, making it easier to conceal the fact that the drug has been diluted. API cutting agents have helped traffickers to maintain steady supplies in the face of successful interdiction and even expand the market in the UK, particularly to young people aged from their mid teens to early twenties. From importation to street-level, the purity of the drug can be reduced up to a factor of 80 and street level cocaine can have a cocaine content as low as 1%. In view of the increasing use of Benzocaine as cutting agent for Cocaine, a study was carried out to investigate if 2H, 13C, 15N and 18O stable isotope signatures could be used in conjunction with multivariate chemometric data analysis to determine potential linkage between benzocaine exhibits seized from different locations or individuals to assist with investigation and prosecution of drug distribution network. More than 40 Benzocaine samples comprising both seized and control samples were analysed by two stable isotope forensic laboratories in two different countries (Australia and Scotland) to assess intra-lab reproducibility as well as inter-lab repeatability of measured stable isotope abundance values.

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

2012-04-01

74

An investigation of techniques for the measurement and interpretation of cosmic ray isotopic abundances. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

An instrument, the Caltech High Energy Isotope Spectrometer Telescope was developed to measure isotopic abundances of cosmic ray nuclei by employing an energy loss - residual energy technique. A detailed analysis was made of the mass resolution capabilities of this instrument. A formalism, based on the leaky box model of cosmic ray propagation, was developed for obtaining isotopic abundance ratios at the cosmic ray sources from abundances measured in local interstellar space for elements having three or more stable isotopes, one of which is believed to be absent at the cosmic ray sources. It was shown that the dominant sources of uncertainty in the derived source ratios are uncorrelated errors in the fragmentation cross sections and statistical uncertainties in measuring local interstellar abundances. These results were applied to estimate the extent to which uncertainties must be reduced in order to distinguish between cosmic ray production in a solar-like environment and in various environments with greater neutron enrichments.

Wiedenbeck, M. E.

1977-01-01

75

Recovery of enriched stable isotopes in radionuclide production  

SciTech Connect

The wide application of radionuclides in different fields of science and industry demanded an increase of their production. One of the ways to increase the radionuclide production on present cyclotrons is the use of the targets from enriched stable isotopes. This allows one to raise the productivity in some cases by two or more times and to increase radionuclidic purity. It should be noted, however, that enriched stable isotopes are very expensive. Therefore it is advisable to use such raw materials more than once. In the last ten years, The authors have used stable isotopes extensively for making of targets. Zinc-67 and zinc-68, cadmium-111 and cadmium-112, nickel-58, silver-109, thallium-203 have been employed for the production of gallium-67, indium-111, cobalt-57, cadmium-109 and thallium-201, respectively. The technique for the recovery of enriched stable isotopes has been developed. In this report the schemes of the recovering processes are presented.

Razbash, A.A.; Sevastyanov, Yu.G.; Polyakov, O.N.; Krasnov, N.N.; Konyakhin, N.A.; Tolstouhov, Yu.V.; Maklachkov, A.G. [Cyclotron Co. Ltd., Obninsk (Russian Federation)

1994-12-31

76

Stable isotope sales: Mound customer and shipment summaries. FY 1989.  

National Technical Information Service (NTIS)

This report lists Mound's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, chlorine, bromine, and sulfur for fiscal year 1989. Purchasers are listed alphabetically and are divided into domestic and foreign groups. Cross-reference indexes...

K. A. Flayler

1991-01-01

77

The abundances of isotopes in the cosmic radiation  

NASA Technical Reports Server (NTRS)

Studies of the isotopic composition of nuclei in the cosmic radiation are reviewed, including abundances of the isotopes of elements from H to Ni, together with their implications for cosmic ray origin, acceleration, and transport in the Galaxy. The review focuses on determinations of the composition of cosmic ray source material, and the extent to which the isotopic composition of this material is different from, or similar to, typical solar system material and other samples of Galactic matter. Theoretical models that have been advanced to explain the observed overabundance of neutron-rich isotopes in cosmic rays are described. Also discussed are studies of various radioactive clocks that record the time-scales associated with the nucleosynthesis, acceleration, and transport of cosmic ray nuclei, and studies of the so-called anomalous cosmic ray component, thought to represent a sample of the neutral interstellar medium.

Mewaldt, R. A.

1989-01-01

78

Radiogenic and stable isotope variations accompanying continental weathering  

NASA Astrophysics Data System (ADS)

Many natural isotope systems, both stable and radiogenic, are sensitive to variations in weathering processes, but the difficulty remains in distinguishing variations that result from weathering from those caused by differences in rock type. One approach that circumvents this problem is the study of monolithologic catchments, where variations in physical and chemical weathering rates, runoff, catchment age, vegetative and glacial cover can be related to river chemistry. This study presents an overview of our recent work on radiogenic and stable isotopes in rivers and estuaries from Iceland, draining basaltic terrains, where variations in glacial cover result in a wide range of weathering conditions. Each radiogenic and stable isotope system reveals complementary information on the nature of the weathering process, and the estuarine data indicates how this signal is transferred to the oceans. For the dissolved riverine phase, in the absence of variations in rock type, the principal controls on isotope variations accompanying weathering are; (i) For many radiogenic isotope systems, preferential (incongruent) weathering of specific mineral phases, where those phases possess a markedly different parent/daughter ratio, and hence radiogenic isotope composition; (ii) For many stable isotope systems, preferential removal of an isotope into secondary phases formed during weathering, leaves residual waters depleted in that isotope. Despite the wide range of isotope compositions in the dissolved load, for Iceland it is the nature of weathering of the suspended load in the estuarine environment that likely dominates the signal to the oceans. Moreover, both the flux and nature of the suspended load are highly dependent on riverine discharge, and hence climate change. These results clearly demonstrate that weathering processes can exert a significant influence on the riverine isotope signal to the oceans, and for some isotopes marine sedimentary archives will preserve a record of changes in weathering in response to climatic or tectonic change. The challenge remains in deconvolving the effects of weathering from those caused by variations in rock type, or a simple change in the weathering flux.

Burton, K. W.; Gannoun, A.; Georg, B.; Gislason, S. R.; James, R. H.; Parkinson, I. J.; Pogge von Strandmann, P. A.; Mokadem, F.

2007-12-01

79

Stable isotope analysis of nutrient pathways leading to Atlantic salmon  

Microsoft Academic Search

The relative contribution of terrestrial and aquatic primary energy sources in food webs along a stream continuum in the Miramichi River system, New Brunswick, was investigated through the use of stable carbon and nitrogen isotope ratios. In sites where these primary energy sources were isotopically distinct, quantitative mixing models were used to identify the relative importance of allochthonous carbon in

Richard R. Doucett; G. Power; D. R. Barton; R. J. Drimmie; R. A. Cunjak

1996-01-01

80

Carbon Stable Isotopes as Indicators of Coastal Eutrophication  

EPA Science Inventory

Coastal ecologists and managers have frequently used nitrogen stable isotopes (?15N) to trace and monitor anthropogenic nitrogen (N) in coastal ecosystems. However, the interpretation of ?15N data can often be challenging, if not confounding, as the isotope values fr...

81

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...

82

Microbiological fractionation of stable sulfur isotopes: A review and critique  

Microsoft Academic Search

Microbiological transformations of sulfur compounds discriminate to various degrees between the stable sulfur isotopes S and S. Comparatively little is known on isotopic effects associated with sulfur?oxidizing organisms, and the interpretation of results is complicated since the sulfur pathways are poorly defined and compounds containing two or more sulfur atoms at different oxidation states may be involved. Dissimilatory reduction of

L. A. Chambers; P. A. Trudinger

1979-01-01

83

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

PubMed

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

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

2014-01-01

84

Stable isotope ecology in the Omo-Turkana Basin.  

PubMed

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

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

2011-01-01

85

A New Stable Isotope Record From the Subantarctic Southeastern Pacific  

NASA Astrophysics Data System (ADS)

Few stable isotope records exist from the southeast Pacific Ocean due to its remote location, low sedimentation rates, and shallow carbonate compensation depth (CCD). The CCD in the southeast Pacific, however, has been found to be unusually deep (~4750 m), thereby allowing for the preservation of Neogene carbonates at abyssal depths. Herein we present stable isotope results from MV0502-4JC, which was recently recovered from the subantarctic region of the Southwest Pacific (5020S, 14808W, 4286 m). Dating the record with radiolarian biostratigraphy, we have generated a benthic stable isotope record back to the Middle Miocene from Cibicidoides spp. and a planktic record from Globigerina bulloides into the Late Pliocene. These stable isotope records, in conjunction with carbonate contents and counts of ice-rafted debris (IRD) and manganese micronodules show the effect of global ice sheet build up on this poorly understood region. A prominent negative ?13C shift of ~1 (from ~1 to ~0.2) in the benthic record occurs at ~15.3 MBSF (Middle Miocene) as carbonate contents in the core decrease from ~80% to ~20%, and significant changes in the bottom water are indicated by changes in the dominant Cibicidoides spp. at the site from C. robertsonianus to C. wuellerstorfi. Trace amounts of IRD and abundant manganese micronodules also appear at the site at this time. A significant hiatus (from the Late Miocene to the Middle Pliocene) occurs somewhere between 11.4 and 9.8 MBSF. From 9.8 to 8 MBSF (Late Pliocene) benthic ?18O increases and ?13C decreases by ~1. Also, IRD increases, manganese micronodules decrease, and there is a dramatic increase in the preservation of planktic foraminifera at the site. A planktic ?13C shift of >1 (from 0 to 1) occurs at ~5 MBSF (Pleistocene) coincident with a 20% increase in carbonate concentration. After this interval, the variability in both benthic ?18O and ?13C and planktic ?18O increases significantly. We interpret the negative ?13C shift at 15.3 MBSF as the end of the Monterey Carbon Excursion (~13.5 Ma), and the decrease in carbonate observed in MV0502-4JC following this shift may correspond with a widespread hiatus (NH3) associated with the increased presence Antarctic Bottom Water (AABW) in the Pacific and shoaling of the lysocline. The significant hiatus in the Late Miocene-Early Pliocene may also indicate increased AABW formation and Antarctic Circumpolar Current strength during key periods of ice sheet expansion on Antarctica. The ~1 increase in benthic ?18O in the Late Pliocene is interpreted as the onset of Northern Hemisphere Glaciation, although the planktic ?18O record oddly does not show this trend. Increased lysocline depth during the Late Pliocene preceded the high (~30 cm kyr-1) sedimentation rates of the Early Pleistocene that may have resulted from reduced bottom water currents and/or increased productivity. The Late Pleistocene was associated with lower sedimentation rates perhaps associated with increased non-carbonate productivity and increased AABW production during glacial intervals.

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

2007-12-01

86

Stable Chlorine Isotope Study: Application to Early Solar System Materials  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

87

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

E-print Network

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

Waikato, University of

88

Stable isotope paleoaltimetry of the Mount Everest region  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

89

The isotope abundances and the atomic weight of cadmium by a metrological approach  

Microsoft Academic Search

Gravimetric synthetic mixtures of seven enriched, purified cadmium isotope materials were used to determine the correction factors for mass fractionation (MC-TIMS) and mass discrimination (MC-ICP-MS). The isotope abundance ratios determined for various natural cadmium materials represents the isotope composition for natural cadmium materials. Correction of the isotope abundance ratios observed yielded isotope abundances of 106Cd 0.012450(8), 108Cd 0.008884(4), 110Cd 0.124846(16),

W. Pritzkow; S. Wunderli; J. Vogl; G. Fortunato

2007-01-01

90

The Abundance and Isotopic Composition of Hg in Extraterrestrial Materials  

NASA Technical Reports Server (NTRS)

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

Lauretta, D. S.

2004-01-01

91

Tritium and stable isotopes of magmatic waters  

Microsoft Academic Search

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

F. Goff; G. M. McMurtry

2000-01-01

92

The geochemistry of the stable carbon isotopes  

Microsoft Academic Search

Several hundred samples of carbon from various geologic sources have been analyzed in a new survey of the variation of the ratio C 13 \\/C 12 in nature. Mass spectrometric determinations were made on the instruments developed by H. C. and his co-workers utilizing two complete feed systems with magnetic switching to determine small differences in isotope ratios between samples

Harmon Craig

1953-01-01

93

The abundance and isotopic composition of Cd in iron meteorites  

NASA Astrophysics Data System (ADS)

Cadmium is a highly volatile element and its abundance in meteorites may help better understand volatility-controlled processes in the solar nebula and on meteorite parent bodies. The large thermal neutron capture cross section of 113Cd suggests that Cd isotopes might be well suited to quantify neutron fluences in extraterrestrial materials. The aims of this study were (1) to evaluate the range and magnitude of Cd concentrations in magmatic iron meteorites, and (2) to assess the potential of Cd isotopes as a neutron dosimeter for iron meteorites. Our new Cd concentration data determined by isotope dilution demonstrate that Cd concentrations in iron meteorites are significantly lower than in some previous studies. In contrast to large systematic variations in the concentration of moderately volatile elements like Ga and Ge, there is neither systematic variation in Cd concentration amongst troilites, nor amongst metal phases of different iron meteorite groups. Instead, Cd is strongly depleted in all iron meteorite groups, implying that the parent bodies accreted well above the condensation temperature of Cd (i.e., ?650 K) and thus incorporated only minimal amounts of highly volatile elements. No Cd isotope anomalies were found, whereas Pt and W isotope anomalies for the same iron meteorite samples indicate a significant fluence of epithermal and higher energetic neutrons. This observation demonstrates that owing to the high Fe concentrations in iron meteorites, neutron capture mainly occurs at epithermal and higher energies. The combined Cd-Pt-W isotope results from this study thus demonstrate that the relative magnitude of neutron capture-induced isotope anomalies is strongly affected by the chemical composition of the irradiated material. The resulting low fluence of thermal neutrons in iron meteorites and their very low Cd concentrations make Cd isotopes unsuitable as a neutron dosimeter for iron meteorites.

Kruijer, Thomas S.; Sprung, Peter; Kleine, Thorsten; Leya, Ingo; Wieler, Rainer

2013-12-01

94

Variations in carbon and nitrogen stable isotopes of cryoconite  

NASA Astrophysics Data System (ADS)

Cryoconite is biogenic surface dust on snow and ice, and is commoly observed on glaciers worldwide. Because of their dark coloration, cryoconite substantially reduce surface albedo and accelerate melting of glaciers. Therefore, it is important to understand formation process of cryoconite to evaluate its effect on glacier melting. Although cryoconite consists of mineral particles and organic matter, organic fraction is more important in terms of albedo effect because it is usually darker color and accounts for major part of cryoconite in volume. The organic matter is derived from photosynthetic microbes such as cyanobacteria, and/or from windblown organic matter from ground soil around glaciers. Carbon (C) and nitrogen (N) stable isotopes of the organic matter could be useful to know their sources and to understand their cycles on glaciers. In this study, I analyzed carbon and nitrogen stable isotopes of cryoconite collected from 6 sites of different elevation from May to September on an Alaska glacier (Gulkana Glacier) to know their spatial and seasonal variations. I also analyze those collected from glaciers in Asia and Arctic to compare them among different geographical locations. Results on the Alaska glacier show that C and N stable isotopes of cryoconite organic mater significantly varied among elevations and seasons. C isotope was generally higher in lower elevation, probably due to higher photosynthetic activity in the lower elevation. In contrast, N isotope was constant on the ice area, but was lower in the snow area where the red snow algae were blooming. N isotope may be reflective of nitrogen availavility on the glacier surface. Geograpical comparison shows large variations in C and N isotopes among regions: higher C and N isotopes on Asian glaciers, lower C and N isotopes in Alaska, and lower C and higher N isotopes on Arctic glaciers. The isotope values suggest that algal production is a major carbon source on most of glaciers, but their productivity and nirotogen cycle largely varied among the regions.

Takeuchi, N.

2012-12-01

95

[Blood volume measurement of newborn using stable isotope 50Cr].  

PubMed

A technique for the blood volume measurement of newborns was established in which nonradioactive 50Cr was used in patients for whom radioactive labels were not advisable. The red blood cells (RBC) in the newborn's blood withdrawn from umbilical cord after birth were tagged with enriched stable isotope 50Cr (96%, normal abundance 4.3%) and reinjected into the newborn. Blood samples (0.5 ml) were withdrawn at 30 min and thereafter at 6, 12, 24, 48, 72 and 120 hours old. Samples were centrifugalized and portion of RBC was then freeze-dried, weighed and sealed into polyethylene sheet bag together with 50Cr standard. Neutron irradiation was performed in the reactors of the JAERI with thermal neutron flux 5 X 10(13), 2 X 10(13), 8 X 10(13) cm-2s-1 at JRR-2, -3 and -4 respectively for 20 min and samples were left for about two weeks after irradiation. Induced radioactivity (51Cr, 59Fe) of the sample was measured with a Ge(Li) gamma-ray detector system and 4096 channels pulse height analyzer. Analysis of activity data was carried out by BOB-76 code. The RBC and total blood volume of the newborn was calculated using an isotopic dilution technique. We have investigated on tagging efficiency of 50Cr to RBC, washing effect and dilution rate by 50Cr content or 51Cr/59Fe ratio. Significant difference was observed in the total blood volume of newborns depending on the delivery style and in addition, it changed dynamically along the time elapsed after birth. PMID:4011960

Yamabayashi, H; Izumo, M; Motoki, R; Yamamoto, T; Nishida, H; Shin, S; Sato, K; Suzuki, Y

1985-03-01

96

Isotopic consequences of consumer food choice: Hydrogen and oxygen stable isotope ratios in foods from fast food restaurants versus supermarkets  

E-print Network

in stable isotope analysis have made it possible to investigate the region-of-origin claims of goodsIsotopic consequences of consumer food choice: Hydrogen and oxygen stable isotope ratios in foods patrons. We observed no correlations between the stable isotopic composition of carbohydrates and local

Ehleringer, Jim

97

Stable Isotope Ratios and the Forensic Analysis of Microorganisms  

SciTech Connect

In the aftermath of the anthrax letters of 2001, researchers have been exploring various analytical signatures for the purpose of characterizing the production environment of microorganisms. One such signature is stable isotope ratios, which in heterotrophs are a function of nutrient and water sources. Here we discuss the use of stable isotope ratios in microbe forensics, using as a database the carbon, nitrogen, oxygen and hydrogen stable isotope ratios of 247 separate cultures of B. subtilis 6051 spores produced on a total of 32 different culture media. In the context of using stable isotope ratios as a signature for sample matching, we present an analysis of variation between individual samples, between cultures produced in tandem, and between cultures produced in the same medium but at different times. Additionally, we correlate the stable isotope ratios of carbon, nitrogen, oxygen, and hydrogen for growth medium nutrients or water with those of spores and show examples of how these relationships can be used to exclude nutrient or water samples as possible growth substrates for specific cultures.

Kreuzer-Martin, Helen W.; Jarman, Kristin H.

2007-06-01

98

Stable Isotopic Analyses of Laetoli Fossil Herbivores  

Microsoft Academic Search

\\u000a In order to further refine early hominin paleoecology at Laetoli, over 500 specimens of fossil enamel and ostrich eggshell\\u000a fragments collected from the Laetolil Beds and the Upper Ndolanya Beds were analyzed isotopically. The goal was to develop\\u000a a high-resolution spatio-temporal framework for identifying and characterizing foraging patterns of mammalian herbivore lineages\\u000a and fossil ostriches that could be used to

John D. Kingston

99

Spectral analysis software improves con dence in plant and soil water stable isotope analyses performed by isotope ratio infrared  

E-print Network

Spectral analysis software improves con dence in plant and soil water stable isotope analyses with the types of spectral interference that compromises their stable isotope analysis. Here we report two of stable iso- tope analysis of water. The stable isotope composition of pure water analyzed by IRIS

Goldsmith, Greg

100

Distinguishing sources of N2O in European grasslands by stable isotope analysis  

Microsoft Academic Search

Nitrifiers and denitrifiers are the main producers of the greenhouse gas nitrous oxide (N2O). Knowledge of the respective contributions of each of these microbial groups to N2O production is a prerequisite for the development of effective mitigation strategies for N2O. Often, the differentiation is made by the use of inhibitors. Measurements of the natural abundance of the stable isotopes of

Nicole Wrage; Jutta Lauf; Agustin del Prado; Miriam Pinto; Stefan Pietrzak; Sirwan Yamulki; Oene Oenema; Gerhard Gebauer

2004-01-01

101

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

SciTech Connect

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

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

2011-03-04

102

Use of Stable Isotopes in Forensic Analysis of Microorganisms  

SciTech Connect

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

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

2012-01-18

103

A stable isotope dilution method for measuring bioavailability of organic contaminants  

PubMed Central

Methods for determining bioavailability of organic contaminants suffer various operational limitations. We explored the use of stable isotope labeled references in developing an isotope dilution method (IDM) to measure the exchangeable pool (E) of pyrene and bifenthrin as an approximation of their bioavailability in sediments. The exchange of deuterated bifenthrin or pyrene with its native counterpart was completed within 48 h. The derived E was 3882% for pyrene and 2859% for bifenthrin. Regression between E and the sum of rapid and slow desorption fractions obtained from sequential desorption showed a slope close to 1.0. The ability of IDM to predict bioavailability was further shown from a strong relationship (r2 > 0.93) between E and bioaccumulation into Chironomus tentans. Given the abundance of stable isotope labeled references and their relatively easy analysis, the IDM has the potential to become a readily adoptable tool for estimating organic contaminants bioaccessibility in various matrices. PMID:23434573

Delgado-Moreno, Laura; Gan, Jay

2014-01-01

104

Stable platinum isotope measurements in presolar nanodiamonds by TEAMS.  

PubMed

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

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

2013-01-01

105

Stable isotope geochemistry of East African waters. [Abstract only  

SciTech Connect

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

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

1983-03-01

106

Stable isotope composition of water in desert plants  

Microsoft Academic Search

A survey of the stable isotope content of tissue waters of plants from the Negev desert was conducted. Large differences were\\u000a observed in the extent of enrichment of the heavy isotopes in leaf water relative to local precipitation among different plants.\\u000a This is apparently caused by the species-dependent stratagems adopted by the plants to cope with water stress, primarily by

J. R. Gat; D. Yakir; G. Goodfriend; P. Fritz; P. Trimborn; J. Lipp; I. Gev; E. Adar; Y. Waisel

2007-01-01

107

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

NASA Astrophysics Data System (ADS)

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

Yang, Weifeng; Guo, Laodong

2014-11-01

108

Stable isotopes determination in some Romanian wines.  

PubMed

This paper presents a study concerning the isotopic fingerprint ((18)O and (13)C) of some wines prepared from relevant Romanian grape varieties (e.g. Feteasca Alba (FA), Feteasca Regala (FR) and Cabernet Sauvignon (CS)) obtained in different vintage years (2002, 2003, 2004, 2007 and 2008). These wines were obtained from different vineyards having a significant role in the wine market: Cotesti, Tohani, Stefanesti, Aiud, Cotnari, Bucium, Murfatlar, Bujoru, Dragasani and Valea Calugareasca. Several observations related to the dependence of isotope ratios on geographical origin and climatic conditions were drawn. The authentic wines obtained from the FA grape variety from six different vineyards showed ?(18)O values in the range of+3.28 (Cotesti region - 4538'N/2704'E) to-2.60 (Aiud region - 4619'N/2345'E). The ?(13)C values were very similar for all the samples with an average of about-26 . The difference between the ?(18)O values was due to the different climatic zones, which have an influence on the ?(18)O values of wine water. For the wine variety CS obtained from the Dealu Mare-Tohani vineyard, production years 2003 and 2004, a greater difference in the ?(18)O values of wine water ranging from 1.89 (in 2004) to 5.35 (in 2003) was noted. This difference is explained by the different mean annual temperatures in 2003 and 2004. PMID:22397311

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

2012-06-01

109

Stable Isotopic Tracing--A Way Forward for Nanotechnology  

PubMed Central

Numerous publications and reports have expressed health and safety concerns about the production and use of nanoparticles, especially in areas of exposure monitoring, personal use, and environmental fate and transport. We suggest that stable isotopic tracers, which have been used widely in the earth sciences and in metabolic and other health-related studies for several decades, could be used to address many of these issues. One such example we are pursuing is the use of stable isotopes to monitor dermal absorption of zinc and titanium oxides in sunscreen preparations and other personal care products. Other potential applications of this tracing approach are discussed. PMID:17035130

Gulson, Brian; Wong, Herbert

2006-01-01

110

The stable isotopic evolution of a metamorphic complex, Naxos, Greece  

NASA Astrophysics Data System (ADS)

A detailed study of the stable isotope composition of pelites, amphibolites and marbles from the M2 metamorphic complex on Naxos is presented. The low grade rocks of this metamorphic complex have isotopic compositions typical of metasedimentary rocks whilst those at high grades have values typical of igneous rocks. The isotopic compositions of rocks at intermediate grades vary smoothly between these two end-members. This variation is shown to result from the superimposition of at least two fluid flow events on a pre-existing isotopic gradient. The contrast between the observed seemingly simple mixing trend and the complexity of the isotopic history of these rocks has important implications for quantitative studies of fluid-rock interactions.

Baker, Judy; Matthews, Alan

1995-07-01

111

Does avian malaria infection affect feather stable isotope signatures?  

PubMed

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

Yohannes, Elizabeth; Palinauskas, Vaidas; Valki?nas, Gediminas; Lee, Raymond W; Bolshakov, Casimir V; Bensch, Staffan

2011-12-01

112

Middle Pleistocene ecology and Neanderthal subsistence: insights from stable isotope analyses in Payre (Ardche, southeastern France).  

PubMed

The Middle Palaeolithic site of Payre in southeastern France yields abundant archaeological material associated with fossil hominid remains. With its long sequence of Middle Pleistocene deposits, Payre is a key site to study the Middle Palaeolithic chronology of this region. This study is the first to investigate carbon and oxygen isotope contents of Neanderthal tooth enamel bioapatite, together with a wide range of herbivorous and carnivorous species. The aim is to contribute to the understanding of hunting behaviour, resource partitioning, diet and habitat use of animals and Neanderthals through a palaeoecological reconstruction. Local topography had a visible influence on carbon and oxygen stable isotope values recorded in herbivore tooth enamel. This was used to investigate possible habitats of herbivores. The different herbivorous species do not show large variations of their carbon and oxygen isotope values through time, indicating niche conservatism from OIS 8-7 to OIS 6-5, i.e., independently of palaeoclimatic and palaeoenvironmental variations. Based on these new observations, we conclude that Neanderthals employed a stable subsistence strategy over time, using a variety of local resources, with resource partitioning visible between humans and carnivores, especially wolves. A comparison of the results of stable isotopic investigation with the results of tooth wear analyses previously conducted on the same teeth allowed us to demonstrate that grazing and browsing do not bind animals to a specific habitat in a C3 environment as reflected in the isotopic values. PMID:23920410

Ecker, Michaela; Bocherens, Herv; Julien, Marie-Anne; Rivals, Florent; Raynal, Jean-Paul; Moncel, Marie-Hlne

2013-10-01

113

Investigating the diet of the omnivorous mirid Dicyphus hesperus using stable isotopes.  

PubMed

Omnivory involves numerous feeding relationships and a complex web of interactions. When using omnivores in biocontrol, these interactions need to be understood to maximize feeding on the target species and minimize non-target interactions. Dicyphus hesperus is used along with Encarsia formosa for biocontrol of whiteflies in greenhouse tomato crops. Dicyphus hesperus is a generalist omnivore which feeds on all components of the system. To quantify these interactions, stable isotope analysis was used to identify trophic position with nitrogen isotopes (delta15N) and plant sources with carbon isotopes (delta13C). Feeding trials were used to establish baseline isotopic data for D. hesperus and their diet, including Verbascum thapsus, an alternative plant food. Cage trials were used to monitor population abundances and the isotopic signature of D. hesperus. In feeding trials, D. hesperus were enriched relative to their food, suggesting an elevated trophic position. However, large amounts of isotopic variation were found within all diet components, with only V. thapsus exhibiting a distinct signature. In cage trials, the average delta15N and delta13C of the omnivore declined over time, coinciding with declines in total available prey, though it may be confounded by changes in temperature. The range of delta13C, but not the range of delta15N, also declined over time. This suggests a change in the plant source within the diet, but also some unquantified variability within the population. We suggest that diet variability exists within D. hesperus populations, declining as prey become less abundant. PMID:19159499

Bennett, J A; Gillespie, D R; VanLaerhoven, S L

2009-08-01

114

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

115

Stoichiometry effect on stable isotope analysis of dolomite  

Microsoft Academic Search

Dolomite admixed with calcite in partially dolomitized limestones is often nonstoichiometric. Precise stable isotope compositions of these two minerals in such samples are difficult to determine. Differential acid extraction and weak-acid leaching are the two common methods used. In the present study, we evaluate the validity of these methods. Our results show that the reaction rate between dolomite and phosphoric

Tzen-Fu Yui; Shou-Yeh Gong

2003-01-01

116

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...

117

Stable Metal Isotopes Reveal Copper Accumulation and Loss  

E-print Network

Stable Metal Isotopes Reveal Copper Accumulation and Loss Dynamics in the Freshwater Bivalve unidirectional fluxes. However, complicated logistics, handling, and waste issues limit.g., refs 15 and 16). None have dealt with freshwater organisms. Here we present a simple method

118

Stable nitrogen isotopes in Angola Basin surface sediments  

Microsoft Academic Search

Sedimentary ?15N contains a record of biogeochemical processes occurring in the water column. Stable nitrogen isotopes were measured in the bulk sedimentary matter of 18 surface sediment samples collected in three transects in the eastern Angola Basin, perpendicular to the coast, at 6 S, 12 S and 17 S and two samples from the Zaire estuary. Relative enrichment in 15N

M. Elizabeth Holmes; Peter J. Mller; Ralph R. Schneider; Monika Segl; Jrgen Ptzold; Gerold Wefer

1996-01-01

119

Standards for stable isotope measurements in natural compounds  

Microsoft Academic Search

RESEARCH based on stable isotope variations in natural compounds is expanding in scientific fields such as geochemistry, hydrology, environmental studies and biochemistry. However, intercomparison of results obtained in different laboratories is often not fully reliable and therefore to improve the intercalibration of deuterium and 18O measurements in natural waters, two water standards have been distributed by the International Atomic Energy

R. Gonfiantini

1978-01-01

120

Neutron Stimulated Emission Computed Tomography of Stable Isotopes  

E-print Network

Analysis (NAA) also known as Instrumental Neutron Activation Analysis (INAA). The latter terms usually to previous work. It will be helpful to distinguish the physical principal of NSECT from Neutron ActivationNeutron Stimulated Emission Computed Tomography of Stable Isotopes Carey E. Floyd Jr.*ab , Calvin

121

SYNTHESIS Elucidating the nutritional dynamics of fungi using stable isotopes  

E-print Network

). The formation of macroscopic sporocarps (mushrooms) by many ECM and SAP fungi allows for experimentalREVIEW AND SYNTHESIS Elucidating the nutritional dynamics of fungi using stable isotopes Jordan R (SAP) fungi are essential to terrestrial element cycling due to their uptake of mineral nutrients

Henkel, Terry

122

SYNTHESES Elucidating the nutritional dynamics of fungi using stable isotopes  

E-print Network

). The formation of macroscopic sporocarps (mushrooms) by many ECM and SAP fungi allows for experimentalREVIEW AND SYNTHESES Elucidating the nutritional dynamics of fungi using stable isotopes Jordan R (SAP) fungi are essential to terrestrial element cycling due to their uptake of mineral nutrients

Bruns, Tom

123

Stable isotope analysis of breath using the optogalvanic effect  

NASA Astrophysics Data System (ADS)

A new technique based on the optogalvanic effect has been developed for the measurement of stable isotope ratios in the carbon dioxide of exhaled breath. Data obtained before and after ingestion of harmless stable isotope labeled compounds, metabolized to carbon dioxide, can be used for sensitive noninvasive diagnostics of various disease conditions. The technique uses the specificity of laser resonance spectroscopy and achieves sensitivity and accuracy typical of sophisticated isotope ratio mass spectrometers. Using fixed frequency carbon dioxide lasers, 13C/12C ratios can be determined with a precision of 2 ppm with 100 second averaging times. Multiple samples can be analyzed simultaneously providing real time continuous calibration. In a first application, analysis of 13C/12C ratios in exhaled human breath after ingestion of 13C labeled urea is being developed as a diagnostic for the bacterium H-pylori, known to be the causative agent for most peptic and duodenal ulcers.

Murnick, Daniel E.; Colgan, M. J.; Lie, H. P.; Stoneback, D.

1996-05-01

124

Biomedical research applications of electromagnetically separated enriched stable isotopes  

NASA Astrophysics Data System (ADS)

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.

Lambrecht, R. M.

125

Modeled and measured stable isotope data in Siberian tree rings  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

126

Light stable isotope analysis of meteorites by ion microprobe  

NASA Technical Reports Server (NTRS)

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

Mcsween, Harry Y., Jr.

1994-01-01

127

Heavy element stable isotope ratios: analytical approaches and applications.  

PubMed

Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-collector array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies. PMID:23397089

Tanimizu, Masaharu; Sohrin, Yoshiki; Hirata, Takafumi

2013-03-01

128

Utilisation of doubly stable isotopeUtilisation of doubly stable isotope labelledlabelled LactobacillusLactobacillus johnsoniijohnsonii  

E-print Network

isotopic enrichment of specific bloodand the corresponding isotopic enrichment of specific blood plasmaCl) and) and [U[U--1313 CC66]glucose]glucose ((CamproCampro ScientificScientific, Berlin), Berlin) dlLa1dl,12 0,14 0,16 0,18 0,2 supernatant fibrinogen plasma protein precipitate [at%exc] 15N 13C Isotope

129

Stable Isotope Probing Analysis of Interactions between Ammonia Oxidizers?  

PubMed Central

The response of natural microbial communities to environmental change can be assessed by determining DNA- or RNA-targeted changes in relative abundance of 16S rRNA gene sequences by using fingerprinting techniques such as denaturing gradient gel electrophoresis (DNA-DGGE and RNA-DGGE, respectively) or by stable isotope probing (SIP) of 16S rRNA genes following incubation with a 13C-labeled substrate (DNA-SIP-DGGE). The sensitivities of these three approaches were compared during batch growth of communities containing two or three Nitrosospira pure or enriched cultures with different tolerances to a high ammonia concentration. Cultures were supplied with low, intermediate, or high initial ammonia concentrations and with 13C-labeled carbon dioxide. DNA-SIP-DGGE provided the most direct evidence for growth and was the most sensitive, with changes in DGGE profiles evident before changes in DNA- and RNA-DGGE profiles and before detectable increases in nitrite and nitrate production. RNA-DGGE provided intermediate sensitivity. In addition, the three molecular methods were used to follow growth of individual strains within communities. In general, changes in relative activities of individual strains within communities could be predicted from monoculture growth characteristics. Ammonia-tolerant Nitrosospira cluster 3b strains dominated mixed communities at all ammonia concentrations, and ammonia-sensitive strains were outcompeted at an intermediate ammonia concentration. However, coexistence of ammonia-tolerant and ammonia-sensitive strains occurred at the lowest ammonia concentration, and, under some conditions, strains inhibited at high ammonia in monoculture were active at high ammonia in mixed cultures, where they coexisted with ammonia-tolerant strains. The results therefore demonstrate the sensitivity of SIP for detection of activity of organisms with relatively low yield and low activity and its ability to follow changes in the structure of interacting microbial communities. PMID:20154116

Tourna, Maria; Freitag, Thomas E.; Prosser, James I.

2010-01-01

130

Stable isotopes for determining biokinetic parameters of tellurium in rabbits.  

PubMed

We have compared the use of stable and radioactive isotopes for determining the concentration of tellurium in body fluids of animals and man, specifically in the blood plasma of rabbits. Particular effort has been devoted to developing a sample-processing technique that allows the total amount of tellurium and isotope ratios to be measured by graphite furnace atomic absorption spectrometry (GFAAS) and secondary ion mass spectrometry (SIMS), respectively. The procedure employed in the SIMS analysis is discussed in detail. Investigations on the plasma clearance and the fractional intestinal absorption were carried out on four rabbits. Tracer solutions containing stable tellurium enriched in 124Te or 126Te and radioactive tellurium (121mTe or 123mTe) were administered by gavage and/or intravenously. Blood samples were drawn during the first 2 days after application. The activity of the separated plasma was measured by standard gamma ray spectrometry. After wet ashing and solvent extraction with MIBK the samples were analyzed for stable tellurium. A detection limit of 1 ng/mL of plasma could be achieved with GFAAS. For SIMS analysis the processed samples were deposited on high-purity graphite backings. Reliable isotope ratios could be determined with sample fractions containing 1 ng of tellurium or even less. The results obtained by applying stable isotopes were found to be in good agreement with the data achieved by using radioactive tracers. Studies on the intestinal absorption and the metabolic behavior of tellurium in human volunteers may thus be performed with stable isotopes. PMID:1776699

Kron, T; Wittmaack, K; Hansen, C; Werner, E

1991-11-15

131

STABLE ISOTOPES ISSUE Chris Harrod Jonathan Grey T. Kieran McCarthy  

E-print Network

and nitrogen stable isotope analysis was used to differentiate between European eels (Anguilla anguilla gradient can be extremely plastic and that stable isotope analysis has considerable utilitySTABLE ISOTOPES ISSUE Chris Harrod ? Jonathan Grey ? T. Kieran McCarthy Michelle Morrissey Stable

McCarthy, T.K.

132

Stable isotopes in the diagnosis and treatment of inherited hyperammonemia  

PubMed Central

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

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

2014-01-01

133

Elemental and isotopic abundances in the solar wind  

NASA Technical Reports Server (NTRS)

The use of collecting foils and lunar material to assay the isotopic composition of the solar wind is reviewed. Arguments are given to show that lunar surface correlated gases are likely to be most useful in studying the history of the solar wind, though the isotopic abundances are thought to give a good approximation to the solar wind composition. The results of the analysis of Surveyor material are also given. The conditions leading to a significant component of the interstellar gas entering the inner solar system are reviewed and suggestions made for experimental searches for this fraction. A critical discussion is given of the different ways in which the basic solar composition could be modified by fractionation taking place between the sun's surface and points of observation such as on the Moon or in interplanetary space. An extended review is made of the relation of isotopic and elemental composition of the interplanetary gas to the dynamic behavior of the solar corona, especially processes leading to fractionation. Lastly, connection is made between the subject of composition, nucleosynthesis and the convective zone of the sun, and processes leading to modification of initial accretion of certain gases on the Earth and Moon.

Geiss, J.

1972-01-01

134

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

Microsoft Academic Search

The trophodynamics of pelagic and benthic animals of the North Sea, North Atlantic shelf, were assessed using stable isotope analysis (SIA) of natural abundance carbon and nitrogen isotopes, lipid fingerprinting and compound-specific SIA (CSIA) of phospholipid-derived fatty acids (PLFAs). Zooplankton (z), epi- and supra-benthic macrofauna were collected in the Southern Bight, at the Oyster Grounds and at North Dogger, 111

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

2012-01-01

135

Hydrological investigation of a multi-stratified pit lake using radioactive and stable isotopes combined with hydrometric monitoring  

NASA Astrophysics Data System (ADS)

Pit lakes connected with mine tunnels and shafts may display unique stratification features.A multi-isotopic study has been conducted in a meromictic pit lake with complex stratification.Tritium abundance has provided a plausible lake flooding model.?18O and ?2H isotopes combined with hydrological studies have solved the pit lake dynamics.The physical structure of the lake is very stable and not affected by groundwater flow.

Snchez-Espaa, Javier; Diez Ercilla, Marta; Prez Cerdn, Fernando; Yusta, Iaki; Boyce, Adrian J.

2014-04-01

136

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

Microsoft Academic Search

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

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

1999-01-01

137

Lipid Extraction and the Fugacity of Stable Isotope Values  

NASA Astrophysics Data System (ADS)

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 ?15N. Consequently, correction factors need to be applied to appropriately interpret ?13C and ?15N 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 ?13C values after lipid extraction (??13C) varied widely among categories (eg., species, tissue type) from 0 - 4 , while ??15N values ranged from 0 to 2. Notably, within category variation was nonsignificant and the ?? 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 ??13C and ??15N 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 (??C13, ??15N) after lipid extraction for Tufted Puffins (Fratercula cirrhata) collected July 2010 at Attu Island, Aleutians.

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

2013-12-01

138

Stable Isotope Fractionation of Cr in Carbonaceous and Ordinary Chondrites  

NASA Astrophysics Data System (ADS)

Difficulties with chemical separation and mass spectrometry combined with little expectation of isotopic fractionation at high temperature left the stable isotope geochemistry of Cr almost unknown [1]. The search for ^{53}Cr excess resulting from the decay of the radioactive nuclide ^{53}Mn (T1/2 = 3.5 My) was very successful but the small amount of data produced to date attests to the particularly difficult measurement by TIMS. This preliminary report describes evidence of mass-dependent fractionation of the stable Cr isotopes 50, 52, and 53 as measured by MC-ICPMS in meteorites relative to SRM 979 Cr standard. Cr was purified using cation-exchange chemistry. The yield is ~100 %. The samples were run on the Nu- Plasma HR of UC Davis in pseudo high-resolution mode. The absence of isotopic fractionation induced by the chemical purification has been double checked by 1) processing the standard through the column and 2) running the same sample several times through the columns. In both cases, we observe no difference in the measured isotopic ratio. The external reproducibility, estimated from 13 replicates of Bjurbole, is 50 ppm. The range of the fractionation per mass unit among 7 carbonaceous chondrites (CI, CM, CO, CV and CK) and 5 ordinary chondrites (H, L and LL) is 0.3 . Individual chondrules from Chainpur and Bjurbole have a wider range (0.6 ). All the chondrites analyzed so far are isotopically lighter than the bulk silicate earth (? ^{50/52}Cr=0, [1]). As for Zn [2], Cr isotopes seem to be heavier in ordinary chondrites (-0.23 ) than in carbonaceous chondrites (-0.35 ). Also as for Zn and Cu [2-3], Cr stable isotopes in carbonaceous chondrites are correlated with ? 17O, suggesting a mixing between an isotopically heavy component and an isotopically light one. The correlation between mass-dependent fractionation of Cr and non-mass-dependent ? 17O requires attention and adequate interpretation. References: [1] Johnson and Bullen, 2004, Review in Mineralogy and Geochemistry. [2] Luck et al., 2005 GCA. [3] Luck et al., 2003 GCA.

Moynier, F.; Jacobsen, B.; Yin, Q.

2006-12-01

139

PATTERNS OF NITROGEN AND CARBON STABLE ISOTOPE RATIOS IN MACROFUNGI, PLANTS AND SOILS IN TWO OLD-GROWTH CONIFER FORESTS  

EPA Science Inventory

Natural abundance stable isotope ratios represent a potentially valuable tool for studying fungal ecology. We measured 15N and 13C in ectomycorrhizal and saprotrophic macrofungi from two old-growth conifer forests, and in plants, woody debris, and soils. Fungi, plants, and so...

140

Radiocarbon and stable isotope constraints on Last Glacial Maximum and Younger Dryas ventilation in the western North Atlantic  

Microsoft Academic Search

Foraminiferal abundance, 14C ventilation ages, and stable isotope ratios in cores from high deposition rate locations in the western subtropical North Atlantic are used to infer changes in ocean and climate during the Younger Dryas (YD) and Last Glacial Maximum (LGM). The ?18O of the surface dwelling planktonic foram Globigerinoides ruber records the present-day decrease in surface temperature (SST) of

Lloyd D. Keigwin; Woods Hole

2004-01-01

141

Intrinsic and Synthetic Stable Isotope Marking of Tsetse Flies  

PubMed Central

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

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

2011-01-01

142

Stable Isotope Mapping of Alaskan Grasses and Marijuana  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

143

Infrared Spectroscopy and Stable Isotope Geochemistry of Hydrous Silicate Glasses  

SciTech Connect

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

Stolper, Edward

2007-03-05

144

Tracing Cadmium in the Environment: an Evolving Stable Isotope Approach  

NASA Astrophysics Data System (ADS)

Cadmium (Cd) is a trace constituent in rocks and waters, and like many transition metals is an essential dietary nutrient at low levels but highly toxic in elevated doses. In many respects, cadmium behaves chemically like calcium (Ca) and thus substitutes for Ca in liquid-solid partitioning reactions and generally follows Ca through biogeochemical cycles and metabolic processes. Cd is comprised of 8 stable isotopes, and given the isotopic systematics of environmental Ca it is likely that variations in the stable isotope composition of Cd in natural materials will result from both inorganic and biologic processes. In order to assess the potential of Cd isotope variations to reveal information about sources, metabolic and biogeochemical pathways and fates of environmental Cd, we have initiated a broad study of the stable isotope composition of Cd in a variety of natural and anthropogenically-influenced systems. As an example, here we report the results of the first systematic study of the stable isotope composition of Cd in biologic materials. We focused on the isotopic variability of Cd in tissues of two species of clam collected from the San Francisco Bay estuary, Potamocorbula amurensis which resides in brackish water and Corbicula fluminea which resides in fresh and slightly brackish water. Both clam species concentrate Cd in their soft and hard tissues. During both low-flow conditions in August and high-flow conditions in April, ?116Cd of soft tissues of Potamocorbula was consistently negative and increased down-estuary with increasing salinity (?116Cd is defined as the per mil difference of the 116Cd/110Cd ratio between a sample and our standard, igneous rock BIR-1). Samples collected in August were systematically displaced to higher ?116Cd than those collected in April. Soft tissues of Corbicula collected in both August and April from upstream, fully fresh-water sampling sites had identical ?116Cd, while soft tissues of Corbicula collected from our site at the fresh water-brackish water interface had variable ?116Cd that was approximately 0.4 less negative than that of co-sampled Potamocorbula. These results point to a variety of potential controls on the isotopic distribution of Cd, including differences in aqueous speciation of Cd in saline and fresh waters, species-specific and temporal variations of nutritional sources and distribution of Cd between soft and hard tissues, and changing influences of Cd contamination to the ecosystem.

Bullen, T. D.; Bouse, R. M.; Brown, C. L.; Croteau, M.; Luoma, S. N.; Topping, B. R.

2005-05-01

145

Magnesium stable isotope fractionation in marine biogenic calcite and aragonite  

NASA Astrophysics Data System (ADS)

This survey of magnesium stable isotope compositions in marine biogenic aragonite and calcite includes samples from corals, sclerosponges, benthic porcelaneous and planktonic perforate foraminifera, coccolith oozes, red algae, and an echinoid and brachiopod test. The analyses were carried out using MC-ICP-MS with an external repeatability of 0.22 (2SD for ? 26Mg; n = 37), obtained from a coral reference sample (JCp-1). Magnesium isotope fractionation in calcitic corals and sclerosponges agrees with published data for calcitic speleothems with an average ? 26Mg calcite-seawater = -2.6 0.3 that appears to be weakly related to temperature. With one exception ( Vaceletia spp.), aragonitic corals and sclerosponges also display uniform Mg isotope fractionations relative to seawater with ? 26Mg biogenic aragonite-seawater = -0.9 0.2. Magnesium isotopes in high-Mg calcites from red algae, echinoids and perhaps some porcelaneous foraminifera as well as in all low-Mg calcites (perforate foraminifera, coccoliths and brachiopods) display significant biological influences. For planktonic foraminifera, the Mg isotope data is consistent with the fixation of Mg by organic material under equilibrium conditions, but appears to be inconsistent with Mg removal from vacuoles. Our preferred model, however, suggests that planktonic foraminifera synthesize biomolecules that increase the energetic barrier for Mg incorporation. In this model, the need to remove large quantities of Mg from vacuole solutions is avoided. For the high-Mg calcites from echinoids, the precipitation of amorphous calcium carbonate may be responsible for their weaker Mg isotope fractionation. Disregarding superimposed biological effects, it appears that cation light isotope enrichments in CaCO 3 principally result from a chemical kinetic isotope effect, related to the incorporation of cations at kink sites. In this model, the systematics of cation isotope fractionations in CaCO 3 relate to the activation energy required for cation incorporation, which probably reflects the dehydration of the cation and the crystal surface and bond formation at the incorporation site. This kinetic incorporation model predicts (i) no intrinsic dependence on growth rate, unless significant back reaction upon slow growth reduces the isotope fractionation towards that characteristic for equilibrium isotope partitioning (this may be observed for Ca isotopes in calcites), (ii) a small decrease of isotope fractionation with increasing temperature that may be amplified if higher temperatures promote back reaction and (iii) a sensitivity to changes in the activation barrier caused by additives such as anions or biomolecules or by the initial formation of amorphous CaCO 3.

Wombacher, F.; Eisenhauer, A.; Bhm, F.; Gussone, N.; Regenberg, M.; Dullo, W.-Chr.; Rggeberg, A.

2011-10-01

146

Cr stable isotope fractionation and reaction kinetics in aqueous milieu  

NASA Astrophysics Data System (ADS)

Mass-dependent stable Cr isotope variations show great potential to monitor the natural attenuation of anthropogenic chromate pollution as well as to investigate changes in environmental conditions in the present and the past. However, accurate interpretation of mass-dependent Cr isotope variations requires profound knowledge of the Cr isotope fractionation behaviour during redox transitions and the isotope exchange kinetics of the reactions involved. Here, we present a comprehensive dataset of stable Cr isotope fractionation and reaction kinetics during Cr(III) oxidation, Cr(VI) reduction and isotopic exchange between soluble Cr(III) and Cr(VI) in aqueous milieu. All experiments were carried out with both oxidation states (i.e. Cr(III) and Cr(VI)) in solution, using H2O2 as oxidising as well as reducing agent. The pH conditions were varied to investigate the influence of the different Cr(III) and Cr(VI) species on the Cr isotope fractionation and on the reaction mechanisms during the enforced redox transitions. All Cr stable isotope measurements were performed by high-resolution MC-ICP-MS [1]. The reduction of Cr(VI) to Cr(III) with H2O2 under strongly acidic conditions shows an equilibrium isotope fractionation of ?(53,52Cr)Cr(III)-Cr(VI) of -3.54 0.35 . This value is within uncertainty equal to that of -3.4 0.1 reported by Ellis et al. [2], who used natural sediment and magnetite as reducing agents at pH 6 to 7. At pH = 7 our reduction experiments show a unidirectional, kinetic isotope fractionation ?(53,52Cr)Cr(III)-Cr(VI) of approximately -5 for reduction rates of up to 80 %, but a strong deviation from this Rayleigh-type process for higher reduction rates. However, at a pH value of 7 H2O2 supports the temporary formation and decomposition of Cr(V)-peroxo complexes that might explain this fractionation behaviour and deviation from a single Rayleigh type trend. The oxidation experiments of Cr(III) to Cr(VI) were carried out in alkaline media using H2O2 as reducing agent. The observed, small Cr isotope fractionation can not be explained by one, unidirectional oxidation process. The high energy needed to oxidise Cr(III) to Cr(VI), potential Cr(III) oligomerisation and the formation of Cr(IV) and/or Cr(V) intermediates make the oxidation of Cr(III) to Cr(VI) a very complex fractionation mechanism. Our best-fit modelling points to an overall isotope fractionation ?(53,52Cr)Cr(VI)-Cr(III) of +0.15 during the different oxidation steps, which is overprinted by a much larger isotope fractionation ?(53,52Cr)Cr(III)-Cr(VI) of -3.4 during the back reduction of approximately 15 % of the chromium. No isotope exchange between soluble Cr(VI) and Cr(III) species at pH values of 5.5 and 7 was revealed by our experiments over a timescale of 120 hours. This observation is in good agreement with the lack of isotope exchange between oxygen bound in dissolved chromate CrO42- and that of the surrounding water [3]. [1] Schoenberg, R. et al. (2008) Chemical Geology, 249, 294ff. [2] Ellis, A. et al. (2002) Science, 295, 2060ff. [3] Bullen, T. et al. (2009) Geochim. Cosmochim. Acta, 73 (13), Suppl. 1, A173

Zink, S.; Schoenberg, R.; Staubwasser, M.

2009-12-01

147

Stable Isotopes as Validation Tools for Global Climate Model Predictions of the Impact of Amazonian Deforestation.  

NASA Astrophysics Data System (ADS)

This paper examines changes in isotopic abundances for 18O and deuterium in precipitation over the Amazon basin based on data in the Global Network on Isotopes in Precipitation (GNIP) database from the International Atomic Energy Agency (IAEA)/WMO. The analysis is conducted in the context of recent changes (and anticipated future changes) to the land surface hydrology as a result of tropical deforestation. Statistically significant temporal changes (1965-90) in selected stable isotopic signatures in the Amazon have been compared with global climate model (GCM) predictions revealing notable differences. For example, the wet season deuterium excess differences between Belem and Manaus, Brazil, are consistent with recent GCM simulations only if there has been a relative increase in evaporation from nonfractionating water sources over this period. No significant change in dry season isotopic characteristics is found despite earlier predictions that land-use change signals would be found. Results of GCM simulations of Amazonian deforestation suggest that the recent stable isotope record is more consistent with the predicted effects of greenhouse warming possibly combined with forest removal than with the predicted effects of deforestation alone.

Henderson-Sellers, A.; McGuffie, K.; Zhang, H.

2002-09-01

148

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

SciTech Connect

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

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

2004-01-01

149

Stable Water Isotopes as Evaluation Tools for Global Climate Model Simulations of the Amazon Basin Circulation  

NASA Astrophysics Data System (ADS)

The isotopic abundances of O-18 and Deuterium over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Based on data in the Global Network on Isotopes in Precipitation (GNIP) database, we analyze the simulation of the land surface hydrology and water cycling. Temporal changes between 1965 and 2000 in stable water isotopic signatures in the Amazon have been used to evaluate global climate model (GCM) predictions revealing notable anomalies. For example, the differences in the wet season deuterium excess between Belem and Manaus are consistent with recent GCM simulations only if there has been a relative increase in evaporation from non-fractionating water sources over this period. Despite earlier predictions that land-use change signals would be found, late twentieth century data reveal no significant change in dry season isotopic characteristics. On the other hand, more recent isotopic data do show trends at stations in the Andes, where as much as 88% of the rainfall is thought to be derived from recycled moisture. These data might be linked to land-use change impacts. Simultaneous tracking of the two primary isotopes in water (HDO and H218O) makes it possible to trace the history of evaporative and condensation processes. Results of GCM simulations of Amazonian deforestation suggest that the recent stable isotope record is more consistent with the predicted effects of greenhouse warming, possibly combined with forest removal, than with the predicted effects of deforestation alone. At a minimum, large-scale simulations of South American climate ought to be tested against these isotopic data in any validation effort.

McGuffie, K.; Henderson-Sellers, A.

2003-12-01

150

Mercury Abundances and Isotopic Compositions in the Murchison (CM) and Allende (CV)Carbonaceous Chondrites  

NASA Technical Reports Server (NTRS)

The abundance and isotopic composition of Hg was determined in bulk samples of both the Murchison (CM) and Allende (CV) carbonaceous chondrites using single- and multi-collector inductively coupled plasma mass spectrometry (ICP-MS). The bulk abundances of Hg are 294 6 15 ng/g in Murchison and 30.0 6 1.5 ng/g in Allende. These values are within the range of previous measurements of bulk Hg abundances by neutron activation analysis (NAA). Prior studies suggested that both meteorites contain isotopically anomalous Hg, with d l 96/202Hg values for the anomalous, thermal-release components from bulk samples ranging from 2260 %o to 1440 9/00 in Murchison and from 2620 9/00 to 1540 9/00 in Allende (Jovanovic and Reed, 1976a; 1976b; Kumar and Goel, 1992). Our multi-collector ICP-MS measurements suggest that the relative abundances of all seven stable Hg isotopes in both meteorites are identical to terrestrial values within 0.2 to 0.5 9/00m. On-line thermal-release experiments were performed by coupling a programmable oven with the singlecollector ICP-MS. Powdered aliquots of each meteorite were linearly heated from room temperature to 900 C over twenty-five minutes under an Ar atmosphere to measure the isotopic composition of Hg released fiom the meteorites as a h c t i o n of temperature. In separate experiments, the release profiles of S and Se were determined simultaneously with Hg to constrain the Hg distribution within the meteorites and to evaluate the possibility of Se interferences in previous NAA studies. The Hg-release patterns differ between Allende and Murchison. The Hg-release profile for Allende contains two distinct peaks, at 225" and 343"C, whereas the profile for Murchison has only one peak, at 344 C. No isotopically anomalous Hg was detected in the thermal-release experiments at a precision level of 5 to 30 9/00, depending on the isotope ratio. In both meteorites the Hg peak at ;340"C correlates with a peak in the S-release profile. This correlation suggests that Hg is associated with S-bearing phases and, thus, that HgS is a major Hg-bearing phase in both meteorites. The Hg peak at 225 C for Allende is similar to release patterns of physically adsorbed Hg on silicate and metal grains.

Lauretta, D. S.; Klaue, B.; Blum, J. D.; Buseck, P. R.

2001-01-01

151

Stable Isotope Characterization of TICs/TIMs: Analytical Progress Report  

SciTech Connect

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

Volpe, A M; Singleton, M J

2009-06-05

152

Comparative Glycomics using A Tetraplex Stable-Isotope Coded Tag  

PubMed Central

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

Bowman, Michael J.; Zaia, Joseph

2010-01-01

153

Stable Isotopes of Ice: the Legacy of Willi Dansgaard  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

154

Combining sources in stable isotope mixing models: alternative methods  

Microsoft Academic Search

Stable isotope mixing models are often used to quantify source contributions to a mixture. Examples include pollution source\\u000a identification; trophic web studies; analysis of water sources for soils, plants; or water bodies, and many others. A common\\u000a problem is having too many sources to allow a unique solution. We discuss two alternative procedures for addressing this problem.\\u000a One option is

Donald L. Phillips; Seth D. Newsome; Jillian W. Gregg

2005-01-01

155

Quantifying resource partitioning in centrarchids with stable isotope analysis  

Microsoft Academic Search

Stable isotope and gut content analyses were completed on multiple age classes of Detroit River rock bass (Ambloplites rupestris) and bluegill sunfish (Lepomis macrochirus) to determine the importance of resource parti- tioning in littoral centrarchids. d 15 N signatures ranged from 10.9 to 12.8 in young of the year (YOY) to 7-yr- old rock bass and from 10.3 to 12.1

Gordon Paterson; Kenneth G. Drouillard; G. Douglas Haffner

2006-01-01

156

The use of stable carbon isotope analysis in rooting studies  

Microsoft Academic Search

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

Tony J. Svejcar; Thomas W. Boutton

1985-01-01

157

Stable Carbon Isotopes As Indicators of Plant Water Use Efficiency  

Microsoft Academic Search

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

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

2007-01-01

158

The abundances of elements and isotopes in the solar wind  

NASA Technical Reports Server (NTRS)

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

Gloeckler, George; Geiss, Johannes

1989-01-01

159

Paleoclimate and Amerindians: Evidence from stable isotopes and atmospheric circulation  

PubMed Central

Two Amerindian demographic shifts are attributed to climate change in the northwest plains of North America: at ?11,000 calendar years before present (yr BP), Amerindian culture apparently split into foothillsmountains vs. plains biomes; and from 8,0005,000 yr BP, scarce archaeological sites on the open plains suggest emigration during xeric Altithermal conditions. We reconstructed paleoclimates from stable isotopes in prehistoric bison bone and relations between weather and fractions of C4 plants in forage. Further, we developed a climate-change model that synthesized stable isotope, existing qualitative evidence (e.g., palynological, erosional), and global climate mechanisms affecting this midlatitude region. Our isotope data indicate significant warming from ?12,400 to 11,900 yr BP, supporting climate-driven cultural separation. However, isotope evidence of apparently wet, warm conditions at 7,300 yr BP refutes emigration to avoid xeric conditions. Scarcity of archaeological sites is best explained by rapid climate fluctuations after catastrophic draining of the Laurentide Lakes, which disrupted North Atlantic Deep Water production and subsequently altered monsoonal inputs to the open plains. PMID:11226265

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

2001-01-01

160

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

PubMed

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

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

2001-02-27

161

Stable Isotope Variations in Extraterrestrial Materials Kevin D. McKeegan 1  

E-print Network

1 Stable Isotope Variations in Extraterrestrial Materials by Kevin D. McKeegan 1 and Laurie A bodies of the solar system contain a rich record of isotope variations in the light stable elements. As in isotope geochemistry, this record reflects physical and chemical processes involving isotopic mixing among

162

Instructions for use Experimental Study of the Use of the Stable Isotopic Composition of  

E-print Network

, Carbon, Oxygen, Shallow-water environment, Stable isotope, MART analysis INTRODUCTION The stable carbonInstructions for use #12;Experimental Study of the Use of the Stable Isotopic Composition the isotopic compositions of shallow-water micro- fossils, especially benthic microfossils at high latitudes

Tsunogai, Urumu

163

Using bioenergetics and stable isotopes to assess the trophic role of rusty crayfish  

E-print Network

crayfish relative to other invertebrates. Our diet simulations and stable isotope analysis con- curredUsing bioenergetics and stable isotopes to assess the trophic role of rusty crayfish (Orconectes that crayfish must consume to match observed growth. We compared our model predictions with stable isotope

Vander Zanden, Jake

164

HumanWildlife Interactions 5(1):159167, Spring 2011 Using stable isotope analysis to quantify  

E-print Network

Human­Wildlife Interactions 5(1):159­167, Spring 2011 Using stable isotope analysis to quantify or a population of bears is through stable isotope analysis (SIA), where hair samples can provide an index a range of human attitudes and values within urban areas. Recently, stable isotope analysis (SIA) has

165

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

E-print Network

and Clark 1992; Monteiro et al. 1995; Cherel et al. 2006). Stable isotope analysis (SIA), a technique based1 The role of stable isotopes and mercury concentrations to describe seabird foraging ecology;2 Abstract: Nitrogen (15 N) and carbon (13 C) stable isotopes and contaminants, such as mercury, have been

Boyer, Edmond

166

Variations in the diet of introduced Norway rats (Rattus norvegicus) inferred using stable isotope analysis  

E-print Network

predators; island ecosystem conservation; stable isotope analysis; Norway rats; diet. Correspondence Heather rats and assess predation on least auklets. Using stable isotope analysis we document wide variabilityVariations in the diet of introduced Norway rats (Rattus norvegicus) inferred using stable isotope

Jones, Ian L.

167

A synthesis of tissue-preservation effects on carbon and nitrogen stable isotope signatures  

E-print Network

Helen C. Sarakinos, Michael L. Johnson, and M. Jake Vander Zanden Abstract: Stable-isotope analysis suggest that preserved specimens may be used for stable-isotope analysis and open up the possibilityNOTE A synthesis of tissue-preservation effects on carbon and nitrogen stable isotope signatures

Vander Zanden, Jake

168

Analysis of the hydrogen and oxygen stable isotope ratios of beverage waters without prior water extraction  

E-print Network

Analysis of the hydrogen and oxygen stable isotope ratios of beverage waters without prior water August 2010; Accepted 23 August 2010 Hydrogen (d2 H) and oxygen (d18 O) stable isotope analysis is useful juices. The beverage water stable isotope ratios measured using IRIS agreed well with the IRMS data

Ehleringer, Jim

169

Inherent Variation in Stable Isotope Values and Discrimination Factors in Two Life Stages of Green Turtles  

E-print Network

employing stable isotope analysis so that differences in diet or habitat are more accurately identified. Introduction Stable isotope analysis is commonly used to investigate con- sumer foraging patterns in ecological431 Inherent Variation in Stable Isotope Values and Discrimination Factors in Two Life Stages

170

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

E-print Network

Jason M. Duxbury and Geoffrey L. Holroyd1 Abstract.--Stable isotope ratio analysis (SIRA) was used level of the diets of museum specimens. The analysis of the ratio of stable isotopes of selected2nd Owl Symposium You Are What You Eat: Stable Isotope Ecology of Owl Diets in Alberta, Canada

171

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

PubMed

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

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

2009-01-28

172

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

PubMed

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

Pastor, Ada; Peipoch, Marc; Caas, Ldia; Chappuis, Eglantine; Ribot, Miquel; Gacia, Esperana; Riera, Joan Llus; Mart, Eugnia; Sabater, Francesc

2013-09-17

173

Estimation of evapotranspiration rate in irrigated lands using stable isotopes  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

174

Stable isotope studies: Progress report, March 1985--August 1987  

SciTech Connect

Studies have been carried out in the following areas: Stable Isotope Fractionation (1) Effects of chemical poisons and surface modifiers on polycrystalline platinum electrode surfaces have been investigated with a goal to develop a new form of heterogeneous catalyst for the hydrogen isotope exchange between dihydrogen and water. (2) A new nitrogen-15 fractionation process has been developed, based on the isotope exchange between liquid N/sub 2/O/sub 3/-N/sub 2/O/sub 4/ mixture and their vapor phase at a subambient temperature and a raised pressure. (3) A closed chemical recycle process has been developed for use in connection with the refluxer in the Nitrox-type nitrogen-15 plant. Isotope Effects (1) The vapor pressure isotope effect (VPIE) study of liquid fluoromethanes have been completed. (2) The VPIE study of solid and liquid ammonia has been completed. (3) A theoretical foundation of the additivity for the vibrational zero-point energy (ZPE) has been developed. Studies of Liquid Ammonia. With an aim to study intermolecular interaction (and the inversion phenomenon, in particular) in liquid ammonia, and to further investigate various ammonia solutions, a molecular dynamics (MD) study has been initiated. An MD program has been completed, and force field functions have been developed for an ensemble of non-rigid ammonia molecules. 107 refs., 41 figs., 10 tabs.

Ishida, Takanobu

1987-08-10

175

Bone as a stable isotope archive for local climatic information  

NASA Astrophysics Data System (ADS)

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

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

2004-04-01

176

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

USGS Publications Warehouse

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

Coplen, Tyler B.

2011-01-01

177

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

Microsoft Academic Search

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

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

1963-01-01

178

Stable sulfur isotopic distributions and sulfate reduction in lake sediments of the Adirondack Mountains, New York  

Microsoft Academic Search

Cores from five lakes of the Adirondack Mountains, New York, were analyzed for sedimentary sulfur concentrations and stable sulfur isotopic compositions. Isotopic values of total sedimentary sulfur were as much as 6 to 8 lower than isotopic values of sulfur sources (soils, tree leaves and lake water sulfate) which showed little isotopic variation in the Adirondacks. The low isotopic values

Brian Fry

1986-01-01

179

Controls on stable strontium isotope fractionation in coccolithophores with implications for the marine Sr cycle  

NASA Astrophysics Data System (ADS)

The controls on stable Sr isotope fractionation into the calcite produced by the coccolithophore species Emiliania huxleyi, Coccolithus pelagicus spp. braarudii and Gephyrocapsa oceanica are investigated. Each species has been cultured under controlled laboratory conditions at a range of temperatures (10-25 C) to test the potential of ?88/86Sr as a proxy for growth rate and/or sea surface temperature. Coccolithophores are one of the most abundant pelagic calcifiers; since Sr substitutes to some degree for Ca in their calcite coccoliths, coccolithophores represent a significant output of Sr from seawater, potentially influencing the ?88/86Sr mass balance in the modern oceans. The coccoliths are investigated for their ?88/86Sr, Sr/Ca, and ?18O measured as function of temperature. As temperature is increased all species show a negative stable Sr isotopic fractionation, related to a temperature controlled growth rate. We infer the shift of ?88/86Sr to lighter values as indicative of a kinetic control on the isotope fractionation, revealing the potential of ?88/86Sr as a proxy for growth rate, which in these experiments is primarily dictated by temperature. The results from these experiments indicate that coccolithophore calcite incorporates Sr with a very light ?88/86Sr isotope composition as low as 0.

Stevenson, Emily I.; Hermoso, Michal; Rickaby, Rosalind E. M.; Tyler, Jonathan J.; Minoletti, Fabrice; Parkinson, Ian J.; Mokadem, Fatima; Burton, Kevin W.

2014-03-01

180

Stable isotope analysis using tunable diode laser spectroscopy  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2001-12-01

182

Stable isotope values of North Atlantic water masses  

NASA Astrophysics Data System (ADS)

A comprehensive study of seawater stable isotope properties in the mid-latitude North Atlantic is still missing, especially for the intermediate and deep-water masses. To fill this gap seawater samples were collected since 2006 along various transects in the Northeast Atlantic. During the Atlantic Meridional Transect (AMT) 18 expedition the upper 300 m were sampled between 46.6 and 24.7N. RV Poseidon cruises POS334, POS349, POS377, and POS383 to the Azores Front region (38.3-30N; 22-20W) generally yielded samples down to 2000 m. High-resolution sampling over the whole water column was performed during the OVIDE 2010 (Portugal to Reykjanes ridge) and KN199-4 cruises. Cruise KN199-4 implemented the section from Lisbon to the Cape Verde Islands of the US GEOTRACES North Atlantic transect. Additional stations collected samples along the Iberian margin during the EUROFLEETS Iberia-Forams cruise on RV Garcia del Cid in September 2012. The isotope results clearly indicate the different water masses and hydrographic fronts, although variability in some regions is higher than expected, potentially an affect of the different years and seasons sampled and/ or meandering of the Azores Current. Higher isotope values are observed in the surface waters of the central subtropical gyre and on the southern side of the Azores Front, i.e. within the Azores Current. Lower isotope values are observed in the North Atlantic Deep Water and the Antarctic Intermediate Water upwelled off NW Africa. Mediterranean Outflow Water is best depicted in the Deuterium values because the salinity signal is less rapidly diluted than temperature. Combining the isotope with the respective station's CTD data will allow establishing regional relationships between isotope and temperature/ salinity.

Voelker, Antje

2013-04-01

183

Stable isotope laser spectrometer for exploration of Mars.  

PubMed

On Earth, measurements of the ratios of stable carbon isotopes have provided much information about geological and biological processes. For example, fractionation of carbon occurs in biotic processes and the retention of a distinctive 2-4% contrast in 13C/12C between organic carbon and carbonates in rocks as old as 3.8 billion years constitutes some of the firmest evidence for the antiquity of life on the Earth. We have developed a prototype tunable diode Laser spectrometer which demonstrates the feasibility of making accurate in situ isotopic ratio measurements on Mars. This miniaturized instrument, with an optical path length of 10 cm, should be capable of making accurate 13C/12C and 15N/14N measurements. Gas samples for measurement are to be produced by pyrolysis using soil samples as small as 50 mg. Measurements of 13C/12C, 18O/16O and 15N/14N have been made to a precision of better than 0.1% and various other isotopes are feasible. This laser technique, which relies on the extremely narrow emission linewidth of tunable diode lasers (<0.001 cm(-1)) has favorable features in comparison to mass spectrometry, the standard method of accurate isotopic ratio measurement. The miniature instrument could be ready to deploy on the 2003 or other Mars lander missions. PMID:11541820

Sauke, T B; Becker, J F

1998-01-01

184

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

Microsoft Academic Search

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

Frans Stellaard; Henk Elzinga

2005-01-01

185

Stable Isotope Analysis of Modern Human Hair Collected From Asia (China, India,  

E-print Network

Stable Isotope Analysis of Modern Human Hair Collected From Asia (China, India, Mongolia hair keratin; stable isotope; Asia ABSTRACT We report isotopic data (d2 H, d18 O n 5 196; d13 C, d15 N, and Pakistan (see Fig. 1) and analyzed for stable isotope ratios (d2 H, d18 O, d13 C, d15 N, and d34 S

Ehleringer, Jim

186

Quantitative imaging of subcellular metabolism with stable isotopes and multi-isotope imaging mass spectrometry  

PubMed Central

Multi-isotope imaging mass spectrometry (MIMS) is the quantitative imaging of stable isotope labels in cells with a new type of secondary ion mass spectrometer (NanoSIMS). The power of the methodology is attributable to (i) the immense advantage of using non-toxic stable isotope labels, (ii) high resolution imaging that approaches the resolution of usual transmission electron microscopy and (iii) the precise quantification of label down to 1 part-per-million and spanning several orders of magnitude. Here we review the basic elements of MIMS and describe new applications of MIMS to the quantitative study of metabolic processes including protein and nucleic acid synthesis in model organisms ranging from microbes to humans. PMID:23660233

Steinhauser, Matthew L.; Lechene, Claude P.

2014-01-01

187

An iron stable isotope comparison between human erythrocytes and plasma.  

PubMed

We present precise iron stable isotope ratios measured by multicollector-ICP mass spectrometry (MC-ICP-MS) of human red blood cells (erythrocytes) and blood plasma from 12 healthy male adults taken during a clinical study. The accurate determination of stable isotope ratios in plasma first required substantial method development work, as minor iron amounts in plasma had to be separated from a large organic matrix prior to mass-spectrometric analysis to avoid spectroscopic interferences and shifts in the mass spectrometer's mass-bias. The (56)Fe/(54)Fe ratio in erythrocytes, expressed as permil difference from the "IRMM-014" iron reference standard (?(56/54)Fe), ranges from -3.1 to -2.2, a range typical for male Caucasian adults. The individual subject erythrocyte iron isotope composition can be regarded as uniform over the 21 days investigated, as variations (0.059 to 0.15) are mostly within the analytical precision of reference materials. In plasma, ?(56/54)Fe values measured in two different laboratories range from -3.0 to -2.0, and are on average 0.24 higher than those in erythrocytes. However, this difference is barely resolvable within one standard deviation of the differences (0.22). Taking into account the possible contamination due to hemolysis (iron concentrations are only 0.4 to 2 ppm in plasma compared to approx. 480 ppm in erythrocytes), we model the pure plasma ?(56/54)Fe to be on average 0.4 higher than that in erythrocytes. Hence, the plasma iron isotope signature lies between that of the liver and that of erythrocytes. This difference can be explained by redox processes involved during cycling of iron between transferrin and ferritin. PMID:25017012

von Blanckenburg, Friedhelm; Oelze, Marcus; Schmid, Dietmar G; van Zuilen, Kirsten; Gschwind, Hans-Peter; Slade, Alan J; Stitah, Sylvie; Kaufmann, Daniel; Swart, Piet

2014-10-22

188

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

PubMed

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

Wong, William W; Clarke, Lucinda L

2012-11-01

189

Predation on seabird eggs by Keen's mice (Peromyscus keeni): using stable isotopes to  

E-print Network

Predation on seabird eggs by Keen's mice (Peromyscus keeni): using stable isotopes to decipher.F. Bertram Abstract: We used stable isotope techniques to analyze tissues of Keen's mice (Peromyscus keeni Columbia, western Canada's largest seabird colony. Isotope analysis allowed us to investigate

190

Quantifying Inter-and Intra-Population Niche Variability Using Hierarchical Bayesian Stable Isotope Mixing  

E-print Network

is critical to ecology and evolution. Here we describe a hierarchical stable isotope mixing model that can of population structure. We apply this new approach to stable isotope data from a population of gray wolves from improves mixing models by accounting for diet variability, and improves isotope niche width analysis

191

Stable Isotope Analysis Reveals Variations in Human Diet at the Poundbury Camp Cemetery Site  

Microsoft Academic Search

Stable isotope analysis was undertaken on 48 individuals from Iron Age, Roman and Post-Roman periods of the Poundbury Camp Cemetery, Dorchester, England. Variations in diet, reflected by the stable isotope values, were observed between individuals from the different time periods. Differences in diet within the Late Roman period were particularly interesting, as we found that the isotope values could be

M. P. Richards; R. E. M. Hedges; T. I. Molleson; J. C. Vogel

1998-01-01

192

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

E-print Network

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

Ehleringer, Jim

193

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...

194

Short title: Hygrophoraceae Conservation of biotrophy in Hygrophoraceae inferred from combined stable isotope and  

E-print Network

stable isotope and phylogenetic analyses Brian H. Seitzman1 Department of Biology, 950 Main Street, Clark Hygrophoraceae collected in central Massachusetts and combined with isotopic datasets from five prior studies.3852/10-195 Copyright 2010 by The Mycological Society of America. #12;optimization of stable isotope data suggests

Bruns, Tom

195

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

196

Novel and nontraditional use of stable isotope tracers to study metal bioavailability from natural particles.  

PubMed

We devised a novel tracing approach that involves enriching test organisms with a stable metal isotope of low natural abundance prior to characterizing metal bioavailability from natural inorganic particles. In addition to circumventing uncertainties associated with labeling natural particles and distinguishing background metals, the proposed "reverse labeling" technique overcomes many drawbacks inherent to using radioisotope tracers. Specifically, we chronically exposed freshwater snails ( Lymnaea stagnalis ) to synthetic water spiked with Cu that was 99.4% (65)Cu to increase the relative abundance of (65)Cu in the snail's tissues from ~32% to >80%. The isotopically enriched snails were then exposed to benthic algae mixed with Cu-bearing Fe-Al particles collected from the Animas River (Colorado), an acid mine drainage impacted river. We used (63)Cu to trace Cu uptake from the natural particles and inferred their bioavailability from calculation of Cu assimilation into tissues. Cu assimilation from these particles was 44%, indicating that 44% of the particulate Cu was absorbed by the invertebrate. This demonstrates that inorganic particulate Cu can be bioavailable. The reverse labeling approach shows great potential in various scientific areas such as environmental contamination and nutrition for addressing questions involving uptake of an element that naturally has multiple isotopes. PMID:23458345

Croteau, Marie-Nole; Cain, Daniel J; Fuller, Christopher C

2013-04-01

197

Trophic Ecology of the Armadillo Ant, Tatuidris tatusia, Assessed by Stable Isotopes and Behavioral Observations.  

PubMed

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

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

2014-08-01

198

Mercury emissions and stable isotopic compositions at Vulcano Island (Italy)  

NASA Astrophysics Data System (ADS)

Sampling and analyses methods for determining the stable isotopic compositions of Hg in an active volcanic system were tested and optimized at the volcanic complex of Vulcano (Aeolian Islands, Italy). Condensed gaseous fumarole Hg (fum)T, plume gaseous elemental Hg (g)0 and plume particulate Hg (p)II were obtained at fumaroles F0, F5, F11, and FA. The average total Hg emissions, based on Hg T/SO 2 in condensed fumarolic gases and plumes, range from 2.5 to 10.1 kg y - 1 , in agreement with published values [Ferrara, R., Mazzolai, B., Lanzillotta, E., Nucaro, E., Pirrone, N., 2000. Volcanoes as emission sources of atmospheric mercury in the Mediterranean Basin. Sci. Total Environ. 259(1-3), 115-121; Aiuppa, A., Bagnato, E., Witt, M.L.I., Mather, T.A., Parello, F., Pyle, D.M., Martin, R.S., 2007. Real-time simultaneous detection of volcanic Hg and SO 2 at La Fossa Crater, Vulcano (Aeolian Islands, Sicily). Geophys. Res. Lett. 34(L21307).]. Plume Hg (p)II increases with distance from the fumarole vent, at the expense of Hg (g)0 and indicates significant in-plume oxidation and condensation of fumarole Hg (fum)T. Relative to the NIST SRM 3133 Hg standard, the stable isotopic compositions of Hg are ? 202Hg (fum)T = - 0.74 0.18 (2SD, n = 4) for condensed gaseous fumarole Hg (fum)T, ? 202Hg (g)0 = - 1.74 0.36 (2SD, n = 1) for plume gaseous elemental Hg (g)0 at the F0 fumarole, and ? 202Hg (p)II = - 0.11 0.18 (2SD, n = 4) for plume particulate Hg (p)II. The enrichment of Hg (p)II in the heavy isotopes and Hg (g)0 in the light isotopes relative to the total condensed fumarolic Hg (fum)T gas complements the speciation data and demonstrates a gas-particle fractionation occurring after the gas expulsion in ambient T atmosphere. A first order Rayleigh equilibrium condensation isotope fractionation model yields a fractionation factor ? cond-gas of 1.00135 0.00058.

Zambardi, T.; Sonke, J. E.; Toutain, J. P.; Sortino, F.; Shinohara, H.

2009-01-01

199

A new aquatic gastropod stable isotopic continental paleoclimate proxy for New Zealand systems  

NASA Astrophysics Data System (ADS)

Endemic to New Zealand, the aquatic gastropod Potamopyrgus antipodarum (i.e. New Zealand Mud Snail), is extremely common in modern aqueous environments and is an abundant subfossil preserved in Quaternary sediments throughout the country. This ubiquity presents unprecedented opportunities to explore stable isotope based paleoclimatic and paleoenvironmental research across New Zealands diverse natural systems through time. In an effort to evaluate the utility of New Zealand Mud Snail shells as isotopic proxies, approximately 10 modern snails were collected at each of 18 freshwater systems located throughout New Zealand and analyzed for stable carbon and oxygen isotopic compositions. Results indicate: 1) the oxygen isotope composition of P. antipodarum shells collected from through-flowing lakes and streams exhibit a significant positive correlation with mean annual catchment temperature; 2) shell isotopic compositions typically vary over an approximately 2 permil range for both carbon and oxygen within a single site; 3) inter-site variability is also relatively high with each site defining an isotopically distinct population; 4) shells collected from closed-basin lakes showed markedly more positive delta-values than geographically similar through-flowing systems most likely due to evaporative effects. These results suggest P. antipodarum represents an important new continental climate change proxy for New Zealand systems. However, the modern snail shell results indicate there are also several weaknesses associated with this new proxy. Most importantly, the relatively high degree of natural variability within individual sites indicates multiple contemporaneous shells are needed when performing paleo-research. Additionally, the modern results indicate, as expected, the oxygen isotope composition of snails shells is sensitive to both changes in temperature and hydrologic balance, making it difficult to differentiate between paleo-hydrologic and thermal signals. In an effort to potentially overcome this challenge, the hydrogen isotope composition of shell carbonate was also determined for individual shells. Enough hydrogen, presumably derived from water trapped within shell carbonate, was liberated from 1-2 mg of crushed shell through thermal decomposition followed by continuous flow pyrolysis isotopic analysis. This new technique suggests a multi-proxy method applied to individual aquatic carbonate subfossil specimens is possible.

Horton, T. W.

2009-12-01

200

Subterranean Sympatry: An Investigation into Diet Using Stable Isotope Analysis  

PubMed Central

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

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

2012-01-01

201

Method for cleaning performance evaluation using stable isotopes. Summary report  

SciTech Connect

The Aerospace Guidance and Metrology Center (AGMC) at Newark Air Force Base (NAFB), Ohio, has been using cleaning agents such as 1,1,1-Trichloroethane (TCA) and 1,1,2- Trichloro 1,2,2-trifluoroethane (Freon 113) for repair of inertial guidance equipment. Both of these cleaning agents have been classified as stratospheric ozone layer depleting substance (OLDS). Therefore, AGMC is interested in replacing these with other cleaning agents such as aqueous detergents. In order to assure that reliability and maintainability levels are not degraded when OLDS are phased out, a method is required to validate that the cleaning capability of the suggested alternative is at least as good as that of an existing, proven cleaning agent. The current methods used by AGMC to evaluate cleanliness are not effective when the parts being cleaned are composed of irregular or severe geometrics as is the case for precision gyroscopes and accelerometers repaired at AGMC. Therefore, AGMC funded Battelle to develop and demonstrate a suitable procedure for quantifying cleanliness. This report describes a cleaning performance evaluation procedure (CPEP) based on the use of stable isotopes. The CPEP developed and demonstrated in this project involved two phases. In Phase I, the contaminants which are present in the current cleaning processes were identified to select synthetic inorganic particulate and organic contaminants. In Phase II, unique, stable-isotopes of these contaminants were introduced into the parts followed by cleaning of these parts with various cleaning agents. The amounts of these unique isotopes extracted, as determined by mass spectroscopy (MS) provides a measure of cleaning efficiency.

Chauhan, S.P.; Schumacher, P.; Chuang, J.C.

1992-08-31

202

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

Microsoft Academic Search

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

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

2007-01-01

203

Late Barremianeearly Aptian climate of the northern middle latitudes: Stable isotope evidence from bivalve and cephalopod  

E-print Network

Late Barremianeearly Aptian climate of the northern middle latitudes: Stable isotope evidence from determined on the basis of oxygen isotope analysis of aragonitic bivalve molluscan and ammonoid shells Oxygen isotopes Carbon isotopes Palaeotemperatures Molluscs Ulyanovsk area a b s t r a c

Gilli, Adrian

204

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

SciTech Connect

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

Ishida, T.

1992-10-01

205

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

E-print Network

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

Bindeman, Ilya N.

206

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...

207

Evaluation of Stable Chlorine and Bromine Isotopes in Sedimentary Formation Fluids.  

E-print Network

??Two new analytical methodologies were developed for chlorine and bromine stable isotope analyses of inorganic samples by Continuous-Flow Isotope Ratio Mass Spectrometry (CF-IRMS) coupled with (more)

Shouakar-Stash, Orfan

2008-01-01

208

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

Microsoft Academic Search

Thailands geographical location in the tropics and almost complete, relatively uninterrupted forest cover makes it valuable\\u000a for paleodiet and paleoclimate research. We present the first dietary and environmental reconstructions in Northeastern Thailand,\\u000a using stable isotope abundances in mammalian tooth enamel from the late Middle Pleistocene locality, Tham Wiman Nakin (Snake\\u000a Cave), which reflect a much higher (over 70%) than modern

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

2010-01-01

209

The stable carbon isotopes in enstatite chondrites and Cumberland Falls  

NASA Astrophysics Data System (ADS)

The carbon-isotopic composition (CIC) of the total carbon in the enstatite chondrites Indarch, Abee, St. Marks, Pillistfer, Hvittis and Daniel's Kuil and the enstatite achondrite Cumberland Falls has been measured. The empirical relationship between CIC and total carbon content is distinct from that of carbonaceous and ordinary chondrites. Within the enstatite chondrite group the average C-13 content increases with petrographic type: E4 less than E5 less than E6. Daniel's Kuil shows the largest C-13 enrichment in the bulk carbon of any meteorite. The CIC is most clearly correlated with the abundance of the elements Zn, Cd, and In. Insofar as these elements may hold the key to the understanding of enstatite chondrites, more detailed combined CIC and trace-element studies of these meteorites will play an important role in the deciphering of their history.

Deines, P.; Wickman, F. E.

1985-01-01

210

Sources of organic matter for intertidal consumers on Ascophyllum-shores (SW Iceland): a multi-stable isotope approach  

NASA Astrophysics Data System (ADS)

Stable isotopes were used to examine the origin of organic matter in Icelandic Ascophyllum-based habitats, the role of different organic matters in filling intertidal food webs and the food preferences of the most abundant suspension feeders, grazers and predators. We selected three intertidal sites on the SW coast of Iceland where we sampled in early September 2004, organic matter sources (POM, SOM and most abundant primary producers, A. nodosum and F. vesciculosus) and the most abundant macrofauna species (barnacles, mussels, gastropods, sponge and crabs). Even though the primary production ( Ascophyllum-based) was the same at the three study sites, the isotopic composition of common-among-sites organisms varied due to local differences in the origin of available POM and SOM and in food web structures.

Sar, G.; de Pirro, M.; Romano, C.; Rumolo, P.; Sprovieri, M.; Mazzola, A.

2007-12-01

211

Variations in Lead Isotopic Abundances in Sprague-Dawley Rat Tissues: Possible Reason of Formation  

PubMed Central

It has been reported in previous research that the lead isotopic composition of blood, urine and feces samples statistically differed from the given lead sources in Sprague-Dawley (SD) rats. However, the reason for this phenomenon is still unclear. An animal experiment was performed to investigate the lead isotope fractionation in diverse biological samples (i.e., lungs, liver, kidneys, bone) and to explore the possible reasons. SD rats were intratracheally instilled with lead acetate at the concentrations of 0, 0.02, 0.2, and 2 mg/kg body weight. Biological samples were collected for lead isotope analysis using an inductively coupled plasma mass spectrometry (ICP-MS). Significant differences are observed in lead isotope abundances among the diverse biological samples. The lead isotope abundances (206Pb, 207Pb and 208Pb) in diverse biological samples show different degrees and directions of departure from the given lead source. The results suggest that differences in enrichment or depletion capacity for each lead isotope in the various tissues might lead to the variation in lead isotopic abundances in tissues. Moreover, a nonlinear relationship between the blood lead level and the lead isotope abundances in liver and bone is observed. When the whole-blood level is higher than 50 ng/mL, the lead isotopic compositions of biological samples tend to be the same. Thus, the data support the speculation of a fractionation functional threshold. PMID:24587048

Liu, Duojian; Wu, Jing; Ouyang, Li; Wang, Jingyu

2014-01-01

212

Stable isotope analysis of carbon cycling in the Perdido estuary, Florida  

Microsoft Academic Search

Stable carbon isotope (?13C) analysis was used in the Peridido Estuary, Florida U.S. to determine the predominant carbon source that supports the bacterial\\u000a assemblage. Stable carbon isotope values were measured in the suspended particulate matter (SPM), dissolved organic and inorganic\\u000a matter, and bacteria. Stable nitrogen isotope (?15N) ratios were measured in SPM and nitrate to assist in understanding carbon cycling

Richard B. Coffin; Luis A. Cifuentes

1999-01-01

213

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

NASA Astrophysics Data System (ADS)

Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e. equivalent to ~ 8 ng of amino sugar carbon. Our results obtained from ?13C analysis of amino sugars in selected marine sediment samples showed that muramic acid had isotopic imprints from indigenous bacterial activities, whereas glucosamine and galactosamine were mainly derived from organic detritus. The analysis of stable carbon isotopic compositions of amino sugars opens a promising window for the investigation of microbial metabolisms in marine sediments and the deep marine biosphere.

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

2014-01-01

214

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

215

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

NASA Astrophysics Data System (ADS)

Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment, employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e., equivalent to ~8 ng of amino sugar carbon. Compound-specific stable carbon isotopic analysis of amino sugars obtained from marine sediment extracts indicated that glucosamine and galactosamine were mainly derived from organic detritus, whereas muramic acid showed isotopic imprints from indigenous bacterial activities. The ?13C analysis of amino sugars provides a valuable addition to the biomarker-based characterization of microbial metabolism in the deep marine biosphere, which so far has been lipid oriented and biased towards the detection of archaeal signals.

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

2014-09-01

216

Stable carbon isotopes in bivalve shells as a salinity proxy  

NASA Astrophysics Data System (ADS)

Stable carbon isotopes of dissolved inorganic carbon (?13C-DIC) often vary with salinity in estuarine settings. Variations of salinity in estuaries also complicate temperature reconstructions based on oxygen isotope values in biological carbonates. Therefore having a salinity proxy could assist in estuarine temperature reconstruction as well as providing data on freshwater discharge into the estuary. Unfortunately, ?13C values in bivalve shells are potentially influenced by several sources of carbon including DIC, metabolic carbon and sediment pore-water DIC. This study first investigates the influence of these three potential carbon sources in the Manila clam (Ruditapes philippinarum) reared under laboratory conditions and then in the field during a two-year monitoring study. Metabolic carbon remained fairly constant in the laboratory (~12%) and we did not detect any difference between clams living in organic rich sediments and those in sediment free aquaria. There was a strong correlation between ?13C-shell and ?13C-DIC (r2=0.77) indicating that ?13C-shell can be used as a relative salinity indicator. In the field, calculated salinities were within the range of recorded salinities ( 5 salinity units), but there were significant differences between individuals. This study highlights the potential of using ?13C in bivalve shells as a salinity proxy, but also illustrates that large uncertainties are associated with this proxy.

Gillikin, D. P.; Poulain, C.; Mas, R.; Woule Ebongue, V.; Robert, R.; Paulet, Y.; Lorrain, A.

2010-12-01

217

Stable isotope analysis of white paints and likelihood ratios.  

PubMed

Architectural paints are commonly found as trace evidence at scenes of crime. Currently the most widely used technique for the analysis of architectural paints is Fourier Transformed Infra-Red Spectroscopy (FTIR). There are, however, limitations to the forensic analysis of white paints, and the ability to discriminate between samples. Isotope ratio mass spectrometry (IRMS) has been investigated as a potential tool for the analysis of architectural white paints, where no preparation of samples prior to analysis is required. When stable isotope profiles (SIPs) are compared, there appears to be no relationship between paints from the same manufacturer, or between paints of the same type. Unlike existing techniques, IRMS does not differentiate resin samples solely on the basis of modifier or oil-type, but exploits additional factors linked to samples such as geo-location where oils added to alkyd formulations were grown. In combination with the use of likelihood ratios, IRMS shows potential, with a false positive rate of 2.6% from a total of 1275 comparisons. PMID:19606590

Farmer, N; Meier-Augenstein, W; Lucy, D

2009-06-01

218

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

SciTech Connect

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

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

2009-12-01

219

Isotope abundances of solar coronal material derived from solar energetic particle measurements  

Microsoft Academic Search

Coronal isotopic abundances for the elements He, C, N, O, Ne, and Mg are derived from previously published measurements of the isotopic composition of solar energetic particles by first measuring, and then correcting for, the charge-to-mass-dependent fractionation due to solar flare acceleration and propagation processes. The resulting coronal composition generally agrees with that of other samples of solar system material,

R. A. Mewaldt; E. C. Stone

1989-01-01

220

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

221

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

USGS Publications Warehouse

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

Meier, A.L.

1982-01-01

222

Characterizing the Hydrologic Impacts of Mountaintop Mining Using Stable Isotopes  

NASA Astrophysics Data System (ADS)

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

Zegre, N.; McGuire, K. J.

2011-12-01

223

Insights from Stable Isotopic Tracers on Reproductive Allocation under Stress.  

PubMed

Fecundity is affected by changes in the nutritional and energetic environment, as a result of changes in acquisition, assimilation, or allocation of macro-nutrients and micro-nutrients. Stable isotopes of carbon and nitrogen offer a window into the processes underlying these changes. In insects that feed on nectar as adults, carbon isotopes can be used to trace allocation of carbon to eggs from larval (capital) and adult (income) sources. If adults are fed sugar-water, there is no source of nitrogen from the adult diet. Thus, nitrogen isotopes in eggs reflect fractionation of larval nitrogen due to protein catabolism and anabolism. We subjected adult females of two butterfly species, Speyeria mormonia and Colias eurytheme, to dietary restriction (DR), larval female S. mormonia to DR, and adult female S. mormonia to extra flight. Females subjected to extra flight were previously found to eat more as adults and to have a higher resting metabolic rate. As predicted, significantly less carbon obtained by feeding as adults was incorporated into eggs in both species under DR when adult. Speyeria mormonia eggs contained significantly more carbon derived from adult feeding under DR as larvae and when subjected to extra flight as adult females. Again as predicted, eggs from females of both species subjected to DR when adults were enriched for (15)N, suggesting that increased protein catabolism or anabolism generated additional carbon compounds. Speyeria mormonia eggs from females subjected to DR when larvae or to additional flight as adults were depleted for (15)N. The result for DR of larvae suggests minimization of protein catabolism when protein reserves are relatively scarce. The results for flight were not as predicted, and deserve further exploration. In most cases, isotopic signature in eggs changed with females' age. Eggs were progressively more enriched for the carbon signature of adults, consistent with a two-compartment mixing model for the carbon sources of larvae and adults. Eggs laid across the life of a female were progressively depleted for (15)N, followed by stabilization. This could be due to high total investment in eggs early in life, as the results are consistent with those for other growing animals. Overall, these results indicate shifts in allocation of incoming and stored (capital) carbon in response to various environmental stresses. The results for nitrogen suggest hypotheses to be tested concerning nitrogen metabolism under environmental stress. PMID:24920750

Boggs, C L; Niitepld, K

2014-11-01

224

Stable Carbon Isotopes As Indicators of Plant Water Use Efficiency  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

225

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

226

The abundance of the radioactive isotope Al-26 in galactic cosmic rays  

NASA Technical Reports Server (NTRS)

Satellite observations of the isotopic composition of aluminum in low energy cosmic rays (E/M = 200 MeV/amu) have been used to determine the abundance of the unstable isotope Al-26 (T1/2 = 0.87 Myr). The observed abundance ratio, Al-26/Al-27 = 0.036 (+0.037, -0.022), is in good agreement with previous balloon observations and yields a cosmic ray confinement time consistent with values based on the abundance of Be-10.

Wiedenbeck, M. E.

1983-01-01

227

Biodilution of heavy metals in a stream macroinvertebrate food web: Evidence from stable isotope analysis  

Microsoft Academic Search

Analysis of carbon (?13C) and nitrogen (?15N) stable isotopes provides an increasingly important means of understanding the complex trophic structure of macroinvertebrate communities in streams. We coupled a stable isotope approach with a contaminant analysis of six metals (Pb, Ag, Zn, Hg, Cu, As) to trace the accumulation and dilution of metals from an abandoned mine across trophic levels of

Kozo Watanabe; Michael T. Monaghan; Yasuhiro Takemon; Tatsuo Omura

2008-01-01

228

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

Microsoft Academic Search

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

Joel C. Hoffman; Tracey T. Sutton

2010-01-01

229

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

E-print Network

bimodal distribution of stable isotope ratios of carbon (13 C) among plants in tropical regions (15, 16Detecting intraannual dietary variability in wild mountain gorillas by stable isotope analysis University of New York, New York, NY 10016; b New York Consortium in Evolutionary Primatology, New York, NY

Rothman, Jessica M.

230

Strangers in a Strange Land: Stable Isotope Evidence for Human Migration in the Dakhleh Oasis, Egypt  

Microsoft Academic Search

This study utilizes a combination of both stable oxygen and nitrogen isotope ratios to determine migration patterns for a large sample of human remains from the Kellis 2 cemetery (c. ad250) in the Dakhleh Oasis, Egypt. Stable oxygen isotopic analysis has been used to identify potential migrants in several different populations. In this study, the data resultant from the combination

Tosha L. Dupras; Henry P. Schwarcz

2001-01-01

231

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

E-print Network

with the benthic food web whereas A. rostrata showed stronger links to the pelagic food web. While Lepidion eques was classified as a species linking benthic and benthopelagic food webs, both fatty acid and stable isotope dataTrophic position of deep-sea fish--Assessment through fatty acid and stable isotope analyses G

Pierce, Graham

232

Relation of pathways and transit times of recharge water to nitrate concentrations using stable isotopes  

Microsoft Academic Search

Oxygen and hydrogen stable isotope values of precipitation, irrigation water, soil water, and ground water were used with soil-moisture contents and water levels to estimate transit times and pathways of recharge water in the unsaturated zone of a sand and gravel aquifer. Nitrate-nitrogen (nitrate) concentrations in ground water were also measured to assess their relation to seasonal recharge. Stable isotope

Matthew K. Landon; Geoffrey N. Delin; Stephen C. Komor; Charles P. Regan

2000-01-01

233

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

Microsoft Academic Search

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

JOHN I. HEDGES; ALEXANDER VAN GEEN

1982-01-01

234

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

Microsoft Academic Search

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

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

2010-01-01

235

Comparison of sample preparation methods for stable isotope analysis of dissolved sulphate in forested watersheds  

Microsoft Academic Search

Pretreatment methods for measuring stable sulphur (?S) and oxygen (?O) isotope ratios of dissolved sulphate from watersheds have evolved throughout the last few decades. The current study evaluated if there are differences in the measured stable S and O isotope values of dissolved sulphate from forested watersheds when pretreated using three different methods: Method 1 (M1): adsorb sulphate on anion

Phil-Goo Kang; Bernhard Mayer; Myron J. Mitchell

2012-01-01

236

Dietary variation in arctic foxes ( Alopex lagopus )-an analysis of stable carbon isotopes  

Microsoft Academic Search

We used stable carbon isotopes to analyse individual variation in arctic fox diet. We extracted collagen from bones (the lower jaw), and measured stable carbon isotopes. The foxes came from three different localities: Iceland, where both microtines and reindeer are rare; west Greenland, where microtines are absent; and Sweden, where scat analyses showed the primary food to be microtine rodents

Anders Angerbjrn; Pall Hersteinsson; Kerstin Lidn; Erle Nelson

1994-01-01

237

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...

238

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

Microsoft Academic Search

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

Gundula Muldner; Michael P. Richards

239

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

Microsoft Academic Search

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

Gundula Mldner; Michael P. Richards

2005-01-01

240

Spatial analysis of stable isotope data to determine primary sources of nutrition for fish  

Microsoft Academic Search

Carbon and nitrogen stable isotopes were used to determine the ultimate autotrophic sources supporting production of three commercially important fish species over unvegetated mudflats in a subtropical estuary. Mean isotope values over the whole estuary for fish and autotroph sources were modeled to indicate feasible combinations of sources. Variability in isotope values among nine locations (separated by 310km) was then

Andrew J. Melville; Rod M. Connolly

2003-01-01

241

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

E-print Network

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

242

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

Microsoft Academic Search

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

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

2004-01-01

243

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

PubMed Central

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

Bluck, Les; Volmer, Dietrich A.

2013-01-01

244

Using Stable Isotopes to Estimate Trophic Position: Models, Methods, and Assumptions  

Microsoft Academic Search

The stable isotopes of nitrogen (d15N) and carbon (d13C) provide powerful tools for estimating the trophic positions of and carbon flow to consumers in food webs; however, the isotopic signature of a consumer alone is not generally sufficient to infer trophic position or carbon source without an appropriate isotopic baseline. In this paper, I develop and discuss methods for generating

David M. Post

2002-01-01

245

Stable isotope analysis at the molecular level: A new approach for determining the origins of amino acids in the Murchison meteorite  

Microsoft Academic Search

A combined gas chromatography\\/isotope ratio mass spectrometry (GC\\/IRMS) method has been developed that permits the direct stable carbon isotope analysis of N(O)-trifluoroacetylisopropyl esters of individual amino acids and their respective enantiomers at nanomole abundances. Calculation of the original ?13C values of the amino acids is accomplished via a correction for the carbon introduced during the derivatization process. Previous GC\\/IRMS analyses

M. H Engel; S. A Macko; Y Qian; J. A Silfer

1995-01-01

246

Stable isotope analysis in two sympatric populations of bottlenose dolphins Tursiops truncatus : evidence of resource partitioning?  

Microsoft Academic Search

Skin and muscle from 43 bottlenose dolphins (38 juveniles\\/adults, 5 calves) stranded in NW Spain were analysed to determine\\u000a whether stable isotope ratios (?13C and ?15N) could be used to assess dietary variation, habitat segregation and population substructure. Results were compared with\\u000a published stomach contents data. Stable isotope ratios from 17 known prey species were also determined. Isotope ratios of

Ruth Fernndez; Susana Garca-Tiscar; M. Begoa Santos; Alfredo Lpez; Jose A. Martnez-Cedeira; Jason Newton; Graham J. Pierce

2011-01-01

247

Stable nitrogen isotope analysis of amino Acid enantiomers by gas chromatography/combustion/isotope ratio mass spectrometry.  

PubMed

The analysis of the stable nitrogen isotope compositions of individual amino acid stereoisomers through the use of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) is presented. Nitrogen isotopic compositions of single amino acids or of their enantiomers is possible without the labor-intensive and time-consuming preparative-scale chromatographic procedures required for conventional stable isotope analysis. Following hydrolysis and derivatization, single-component isotope analysis is accomplished on nanomole quantities of each of the stereoisomers of an amino acid, utilizing the effluent stream of gas chromatographic separation. Nitrogen isotope fractionation is minimal during acylation of the amino acid, with no additional nitrogen being added stoichiometrically to the derivative. Thus, the isotopic composition of the nitrogen in the derivative is that of the original compound. Replicate stable nitrogen isotope analyses of 11 amino acids, and their trifluoroacetyl (TFA)/isopropyl (IP) ester derivatives, determined by both conventional isotope ratio mass spectrometry (IRMS) and GC/C/IRMS, indicate that the GC procedure is highly reproducible (standard deviations typically 0.3-0.4) and that isotopic differences between the amino acid and its TFA/IP derivative are, in general, less than 0.5. PMID:21639229

Macko, S A; Uhle, M E; Engel, M H; Andrusevich, V

1997-03-01

248

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

Microsoft Academic Search

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

Jonathan Millett; Roger I. Jones; Susan Waldron

2003-01-01

249

Assessing food web dynamics and relative importance of organic matter sources for fish species in two Portuguese estuaries: A stable isotope approach  

Microsoft Academic Search

Stable carbon and nitrogen isotopes (?13C, ?15N) were used to analyse food web dynamics of two of the main estuaries of the Portuguese coast: Tejo and Mira. The ultimate sources of organic matter supporting production of some of the most abundant and commercially important fish species were determined; and seasonal, inter- and intra- estuarine differences in the trophic relations among

Susana Frana; Rita P. Vasconcelos; Susanne Tanner; Cristina Mguas; Maria Jos Costa; Henrique N. Cabral

2011-01-01

250

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

PubMed

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

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

2014-01-01

251

Climatic and physiological controls on the stable isotope composition of modern and ancient Cupressaceae  

NASA Astrophysics Data System (ADS)

Unique and abundant secondary metabolites found in waxes and resins of the Callitroid, Cupressoid, and Taxodioid clades of the Cupressaceae family can be identified and quantified in complex mixtures of sedimentary organic compounds. This unusual feature makes it possible to study relatively simple (taxon-specific) isotope systems back in time across the broad array of environments in which these conifers are found. Work on these systems can potentially provide both robust paleoenvironmental proxies (i.e. for source water ?D and growing season relative humidity) and quantitative probes into the ecophysiology of these plants in modern and ancient environments. Our research focuses on three genera representing environmental end-members of Cupressaceae - Juniperus, Thuja, and Chamaecyparis - (1) across geographic and environmental gradients in the field, and (2) in specific Holocene and late Pleistocene environmental records. The latter research focuses on peat cores from New England and Oregon and fossil packrat middens from the southwestern United States. Modern transects highlight the sensitivity of Cupressaceae to climatic variables. These include both variables during growth (relative humidity, soil moisture, etc.) and variables affecting seasonal and diurnal growth rates (temperature, winter precipitation, insolation, microhabitat, etc.). Work on ancient records has demonstrated the sensitivity of these unique taxon-specific archives to both subtle and dramatic climate shifts during the Pleistocene and Holocene. This work will result in an improved understanding of climatic and physiological controls on the stable isotopic composition of modern and ancient Cupressaceae - and by extension, other arborescent gymnosperms and C3 plants - providing a framework for understanding more complexly sourced organic inputs to sediments, coals, and petroleum prior to the advent of C4 plants. This research also has direct implications for stratigraphic stable isotope studies of gymnosperm markers across the last millenium, the Pleistocene, and important climatic events in the Mesozoic and Tertiary.

Zinniker, D.; Tipple, B.; Pagani, M.

2007-12-01

252

Stable isotope-based diet reconstructions of Turkana Basin hominins  

PubMed Central

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

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

2013-01-01

253

Stable Isotope Probing of Peat and Forest Floor Amendments  

NASA Astrophysics Data System (ADS)

In Alberta, Canada, land reclamation efforts utilize peat as an organic amendment to help reclaim decommissioned oil sands mine sites to upland boreal forests. This study investigates the rhizosphere microbial communities of two pioneer species, aspen (Populus tremuloides Michx.), a species not known for strong associations with the soil microbial community, and alder (Alnus crispa Ait.), a species well known for mutualism with actinomycetes. Specifically, the objective was to determine how different organic amendments (peat versus forest floor) influenced the rhizosphere microbial communities and how this could be linked to plant growth. Seedlings were grown for 20 weeks in forest floor material, peat, and a combination of both. They were pulse labelled with 13CO2 (g) and subsequently harvested for plant growth measurements. While analysis of plant growth attributes did not indicate any effect of the organic amendment on aspen growth, alder reported significantly less growth in peat treatments. The rhizosphere soils were extracted for compound-specific analysis of ?13C in microbial phospholipid fatty acids. Stable isotope probing showed greater carbon flow between trees and their rhizosphere communities when seedlings were grown in forest floor material.

Quideau, Sylvie; Basse, Mark

2013-04-01

254

Stable isotope studies of nicotine kinetics and bioavailability  

SciTech Connect

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

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

1991-03-01

255

Methylamphetamine synthesized from cold medication as precursor source via two different routes show significantly different stable isotope signatures  

NASA Astrophysics Data System (ADS)

This work exposes the variation in light element stable isotopic abundance values of 13C, 2H and 15N) derived from the analysis of methylamphetamine synthesized via 2 different synthetic routes popular with clandestine laboraties, the Hypophosphorous and the Moscow route. We repeatedly prepared the final product using known clandestine synthetic methods where the precursors, catalysts and reducing agents have themselves been derived from house hold products and commonly available cold medications. Methylamphetamine was prepared from both lab grade pseudoephedrine and pseudoephedrine extracted (using three different solvent systems) from Sudafed, an over-the-counter cold medication widely available in the United Kingdom. Six repetitive batches of the final product were produced in each case to provide within and between batch variations thus yielding a total of 48 samples (24 for each route). We have demonstrated that stable isotope analysis by Isotope Ratio Mass Spectrometry (IRMS) is potentially useful in the comparison and discrimination of batches of methylamphetamine produced for each route and for each precursor depending on the solvent used for extracting the pseudoephedrine starting material. To our knowledge this is the first time multivariate stable isotope analysis has been applied to methylamphetamine samples synthesized from pseudoephedrine extracted from over-the-counter cold medications.

Jayaram, S.; Daeid, N. Nic; Kerr, W. J.; Kemp, H. F.; Meier-Augenstein, W.

2012-04-01

256

Stable isotope analysis indicates a lack of inter- and intra-specific dietary redundancy among ecologically important coral reef fishes  

NASA Astrophysics Data System (ADS)

Parrotfish are critical consumers on coral reefs, mediating the balance between algae and corals, and are often categorised into three functional groups based on adult morphology and feeding behaviour. We used stable isotope analysis (?13C, ?15N) to investigate size-related ontogenetic dietary changes in multiple species of parrotfish on coral reefs around Zanzibar. We compared signatures among species and functional groups (scrapers, excavators and browsers) as well as ontogenetic stages (immature, initial and terminal phase) within species. Stable isotope analysis suggests that ontogenetic dietary shifts occurred in seven of the nine species examined; larger individuals had enriched ?13C values, with no relationship between size and ?15N. The relationship between fish length and ?13C signature was maintained when species were categorised as scrapers and excavators, but was more pronounced for scrapers than excavators, indicating stronger ontogenetic changes. Isotopic mixing models classified the initial phase of both the most abundant excavator ( Chlorurus sordidus) as a scraper and the immature stage of the scraper Scarus ghobban (the largest species) as an excavator, indicating that diet relates to size rather than taxonomy. The results indicate that parrotfish may show similar intra-group changes in diet with length, but that their trophic ecology is more complex than suggested by morphology alone. Stable isotope analyses indicate that feeding ecology may differ among species within functional groups, and according to ontogenetic stage within a species.

Plass-Johnson, J. G.; McQuaid, C. D.; Hill, J. M.

2013-06-01

257

Isotopes in groundwater hydrology  

Microsoft Academic Search

Isotopes in groundwater hydrology give a direct insight into the movement and distribution processes within the aquifer. Groundwater in its natural state contains environmental isotopes and conclusions may be drawn from their abundance variations. The isotopes commonly employed in groundwater investigations are the heavy stable isotopes of the water molecule, deuterium and oxygen-18 and the radioactive isotopes, tritium and carbon-14.

J. L. TERWEY

258

Atmospheric Aerosol Investigation In Vilnius using Stable Carbon Isotopes  

NASA Astrophysics Data System (ADS)

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

Masalaite, Agne; Garbaras, Andrius; Remeikis, Vidmantas

2013-04-01

259

The influence of authigenic clay formation on the mineralogy and stable isotopic record of lacustrine carbonates  

NASA Astrophysics Data System (ADS)

The mineralogical, compositional and stable isotopic variability of lacustrine carbonates are frequently used as proxies for ancient paleoenvironmental change in continental settings, under the assumption that precipitated carbonates reflect conditions and chemistry of ancient lake waters. In some saline and alkaline lake systems, however, authigenic clay minerals, forming at or near the sediment water interface, are a major sedimentary component. Often these clays are rich in Mg, influencing the geochemical budget of lake waters, and are therefore expected to influence the properties of contemporaneous authigenic carbonate precipitates (which may also contain Mg). This paper documents evidence for a systematic feedback between clay mineral and carbonate authigenesis through multiple precessionally driven, m-scale sedimentary cycles in lacustrine oil-shale deposits of the Eocene Green River Formation from the Uinta Basin (NE Utah). In the studied section, authigenic, Mg-rich, trioctahedral smectite content varies cyclically between 9 and 39 wt.%. The highest concentrations occur in oil-shales and calcareous mudstones deposited during high lake level intervals that favored sedimentary condensation, lengthening the time available for clay diagenesis and reducing dilution by other siliciclastic phases. An inverse relation between dolomite percentage of carbonate and trioctahedral smectite abundance suggests the Mg uptake during clay authigenesis provides a first order control on carbonate mineralogy that better explains carbonate mineralogical trends than the possible alternative controls of (1) variable Mg/Ca ratios in lake water and (2) degree of microbial activity in sediments. We also observe that cyclical change in carbonate mineralogy, believed to be induced by clay authigenesis, also causes isotopic covariation between ?13CPDB and ?18OPDB of bulk sediments because of differences in the equilibrium fractionation factors of dolomite and calcite (2 and 2.6%, respectively). This provides an alternative mechanism for the common pattern of isotopic covariation, which is typically attributed to the effect of simultaneous changes in water balance and biological activity on the carbon and oxygen isotopic composition of lake waters. These findings may help improve paleoenvironmental reconstructions based on lacustrine carbonate records by adding to the factors known to influence the mineralogical, compositional and stable isotopic signals recorded by lacustrine carbonates.

Bristow, Thomas F.; Kennedy, Martin J.; Morrison, Keith D.; Mrofka, David D.

2012-08-01

260

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

USGS Publications Warehouse

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

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

2003-01-01

261

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

USGS Publications Warehouse

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

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

2006-01-01

262

Carbon and Sulfur Stable Isotope Records of the Early Paleogene  

NASA Astrophysics Data System (ADS)

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

Dickens, G.; Backman, J.

2012-12-01

263

Soil phosphate stable oxygen isotopes across rainfall and bedrock gradients.  

PubMed

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

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

2012-02-21

264

Retrograde fluids in granulites: Stable isotope evidence of fluid migration  

SciTech Connect

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

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

1991-07-01

265

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

PubMed

Rapid detection of shifts in substrate utilization and energy balance would provide a compelling biofeedback tool for individuals attempting weight loss. As a proof of concept, we tested whether the natural abundance of exhaled carbon stable isotope ratios (breath ?(13)C) reflects shifts between negative and positive energy balance. Volunteers (n=5) consumed a 40% energy-restricted diet for 6 days followed by 50% excess on day 7. Breath was sampled immediately before and 1?h and 2?h after breakfast, lunch and dinner. Exhaled breath ?(13)C values were measured by cavity ring-down spectroscopy. Using repeated measures analysis of variance (ANOVA) followed by Dunnett's contrasts, pre-breakfast breath values on days 2-6 were compared with day 1, and postprandial day 7 time points were compared with pre-breakfast day 7. Energy restriction diminished pre-breakfast breath ?(13)C by day 3 (P<0.05). On day 7, increased energy intake was first detected immediately before dinner (-23.80.6 vs -21.90.7, P=0.002 (meanss.d.)), and breath ?(13)C remained elevated at least 2?h post dinner. In conclusion, when shifting between negative and positive energy balance, breath ?(13)C showed anticipated isotopic changes. Although additional research is needed to determine specificity and repeatability, this method may provide a biomarker for marked increases in caloric intake. PMID:24441037

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

2014-09-01

266

Provenance analysis of Olivella biplicata shell beads from the California and Oregon Coast by stable isotope fingerprinting  

E-print Network

by stable isotope fingerprinting Jelmer W. Eerkens a,*, Gregory S. Herbert b,1 , Jeffrey S. Rosenthal c the potential of stable carbon and oxygen isotopes to source Olivella beads from the Pacific coast. The study Elsevier Ltd. All rights reserved. Keywords: Stable isotopes; California; Oregon; Olivella; Provenance

267

.hnirmil of Mammalogy. 85(5):')95-10()l, 2004 STABLE HYDROGEN ISOTOPE ANALYSIS OF BAT HAIR  

E-print Network

.hnirmil of Mammalogy. 85(5):')95-10()l, 2004 STABLE HYDROGEN ISOTOPE ANALYSIS OF BAT HAIR. Alhiu/uert/ne. NM H7IM. USA fMAB'i United States Geoloi>ical Survey. Stable Isotope and Gas Chemistry. We measured the stable hydrogen isotope ratios ol" bat hair (60,,) and detemiined how these values

268

he stable-hydrogen isotope ratio (D/H or 2H/1H, conventionally expressed as  

E-print Network

, Graham Ekins, Mark Grantham and Andy J. Green Abstract Analysis of the stable-hydrogen isotope content (DT he stable-hydrogen isotope ratio (D/H or 2H/1H, conventionally expressed as D) in bird feathers feathers (showing stable-hydrogen isotope characteristics typical of Siberia) and first-winter feathers

Green, Andy J.

269

Turnover of stable carbon isotopes in the muscle, liver, and breath CO2 of alpacas (Lama pacos)  

E-print Network

2005; Revised 21 February 2006; Accepted 25 February 2006 Stable carbon isotope analysis of animal a single-pool model. Copyright # 2006 John Wiley & Sons, Ltd. Stable isotope analysis is now frequentlyTurnover of stable carbon isotopes in the muscle, liver, and breath CO2 of alpacas (Lama pacos) M

Ehleringer, Jim

270

Feeding Habits of Indian River Lagoon Bottlenose Dolphins Assessed Using Stable Isotope and Fatty Acid Signature Analysis  

E-print Network

Feeding Habits of Indian River Lagoon Bottlenose Dolphins Assessed Using Stable Isotope and Fatty. Recently, the use of naturally occurring carbon and nitrogen stable isotopes has evolved into a powerful for stable isotopic and fatty acid signatures using standard methodologies. Consistent with their different

271

The last GlacialeInterglacial transition in Patagonia, Argentina: the stable isotope record of bulk sedimentary organic matter from Laguna  

E-print Network

. Introduction Stable isotope analysis of bulk organic matter has been widely used in ecological research (eThe last GlacialeInterglacial transition in Patagonia, Argentina: the stable isotope record of bulk Keywords: Stable carbon and nitrogen isotopes Primary productivity Lake sediments South America Last

272

Stable isotope geochemistry of sulfur bearing minerals and clay mineralogy of some soils and sediments in Loot Desert, central Iran  

E-print Network

Stable isotope geochemistry of sulfur bearing minerals and clay mineralogy of some soils Desert Stable isotope geochemistry is a unique technique to study the source of salts in soils and sediments. In the present research, sources of gypsum and other sulfur bearing minerals using stable isotope

Ahmad, Sajjad

273

Assessing Transformation Processes of Organic Compounds Using Stable  

E-print Network

A S C O N I Swiss Federal Institute of Technology (ETH) Zurich Compound-specific stable isotope analysis signatures Compound-specific stable isotope analysis (CSIA) at natural abundance isotope levels opens newAssessing Transformation Processes of Organic Compounds Using Stable Isotope Fractionation T H O M

Gilli, Adrian

274

Stable Water Isotopes as Evaluation Tools for Global Climate Model Simulations of the Amazon Basin Circulation  

Microsoft Academic Search

The isotopic abundances of O-18 and Deuterium over the Amazon are used to constrain simulations of the water cycle in this, the largest river basin in the world. Based on data in the Global Network on Isotopes in Precipitation (GNIP) database, we analyze the simulation of the land surface hydrology and water cycling. Temporal changes between 1965 and 2000 in

K. McGuffie; A. Henderson-Sellers

2003-01-01

275

Stable Isotopes as Validation Tools for Global Climate Model Predictions of the Impact of Amazonian Deforestation  

Microsoft Academic Search

This paper examines changes in isotopic abundances for 18O and deuterium in precipitation over the Amazon basin based on data in the Global Network on Isotopes in Precipitation (GNIP) database from the International Atomic Energy Agency (IAEA)\\/WMO. The analysis is conducted in the context of recent changes (and anticipated future changes) to the land surface hydrology as a result of

A. Henderson-Sellers; K. McGuffie; H. Zhang

2002-01-01

276

Carbon isotopes and light element abundances in carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

A stepped combustion technique was used to measure the abundance of C, N, SO2 and H2O in seven carbonaceous chondrites. Details of the experimental procedures are provided, noting the necessity of adding fresh material at several of the 50 C increments (from 200-1200 C) to compensate for the small sizes of the samples. Samples from the Orgueil, Murchison, Cold Bokkeveld and Murray, Renazzo, Allende and Mokoia meteorites were examined. An extensive tabulation is provided of the elemental releases over various temperature intervals and comparisons are made between the release characteristics observed for the different samples. Emphasis is placed on the types and enrichments of carbon compounds detected and the compositions of the sites where releases occurred.

Halbout, Jerome; Mayeda, Toshiko K.; Clayton, Robert N.

1986-10-01

277

Investigating surface waterwell interaction using stable isotope ratios of water*  

E-print Network

reserved. Keywords: Bank filtration; Hydrogen isotope ratio; Oxygen isotope ratio; Drinking water; Age water quality in a drinking water well, an understanding of the amount of surface water and its travel-floodtraveltimesoflessthan1yearforthissite.Agedatingofonegroundwatersampleusing3 H­3 Hemethods estimated an age longer than 1

278

Lichens and atmospheric sulphur: what stable isotopes reveal  

Microsoft Academic Search

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

Moire A Wadleigh

2003-01-01

279

Extreme changes in stable hydrogen isotopes and precipitation characteristics in a landfalling Pacific storm  

E-print Network

signatures on the resulting precipitation. Notably, precipita- tion with a radar ``brightband'' (BBExtreme changes in stable hydrogen isotopes and precipitation characteristics in a landfalling; published 13 November 2008. [1] With a new automated precipitation collector we measured a remarkable

280

Petrography and Stable Isotopic Trend Associated with Mammoth Hotspring Travertine, Yellowstone National Park, Wyoming  

NASA Technical Reports Server (NTRS)

Active Yellowstone travertines and relict travertines from successively older deposits exhibit a strong linear trend in stable isotopic values indicative of geochemical evolution throughout the course of hotspring activity. Additional information is contained in the original extended abstract.

Guidry, S. A.; Chafetz, H. S.

2002-01-01

281

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...

282

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

E-print Network

This study sought to examine the paleodiet and temporality of a Middle Woodland group from five sites in north central Kansas. This goal was accomplished by submitting 21 samples for stable isotope ratios analysis (SIRA) and 12 samples for bone...

Kauffman, Greg

2013-08-31

283

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

EPA Science Inventory

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

284

Global Climatic and Stable Isotopic Correlations During the Early Permian (Cisuralian)  

E-print Network

and effects of global warming. This study presents new oxygen and carbon stable isotopic data (?18O and ?13C, VPDB) from carefully screened, early Permian brachiopod shells from the Ural Mountains. Using cathodoluminescence (CL) microscopy, 24 specimens were...

Noret, Jordan R.

2009-06-09

285

Stable nitrogen isotope measurements of marine bacterial proteins and nucleic acids: tracers of microbial activity  

E-print Network

Stable nitrogen isotopes ([]15N) can trace elemental cycling in aquatic ecosystems if the enzyme mediated fractionations associated with nutrient uptake and assimilation are negligible or consistently predictable. In this study, bacterial proteins...

Kovacs, Jeffrey Paul

2012-06-07

286

Stable isotopes in biosciences, their measurement and models for amino acid metabolism.  

PubMed

In order to follow the movement and quantify the metabolic fates of biologically important molecules in vivo, both tracers and kinetic modeling are required. For the study of intermediary metabolism in children, stable isotopically labeled substrates satisfy both the analytical and ethical requirements for tracer use in children. Stable isotope tracers have been proven safe over more than a half-century of use in humans. In addition, mass spectrometric analysis of stable nuclide molecular position and isotopic enrichment in biological molecules is both highly specific and extraordinarily precise. Using stable isotope data to develop models of biological system dynamics in vivo is an essential element of estimating substrate events that take place in cells or organs otherwise inaccessible for ethical sampling in children. Further, modeling is also a critical component in the development and the testing of hypotheses about the structure of the biological system in question and the mechanisms which control its operational parameters. PMID:9266207

Bier, D M

1997-08-01

287

Intra-hair stable isotope analysis implies seasonal shift to salmon in gray wolf diet  

E-print Network

, given its predictability, spatial con- straint, caloric content, and lower potential to inflict injury stable isotopes in ani- mal tissue are related to diet and provide an alternative method to estimate food

Reimchen, Thomas E.

288

Stable isotope probing of chemoautotrophic biomarkers in the Cariaco Basin  

NASA Astrophysics Data System (ADS)

In the redoxcline (250-450 m) of the Cariaco Basin, particulate carbon, nitrogen, and biomass (prokaryote, flagellate, viral) concentrations can be > 2-fold the concentrations found in the upper water column. Chemoautotrophic production is sufficient to meet the carbon demands in the redoxcline, yet local electron donor and acceptor sources are insufficient to account for the energy demands of this chemoautotrophy. Parallel experiments using thiosulfate amendments produced a depth-dependent 4 to 33-fold increase in the 14C fixation rate. We are using stable isotope probing on redoxcline waters incubated with 13C labeled bicarbonate and 15N-ammonium with and without thiosulfate amendments to establish the phylogeny and identify the lipid biomarkers associated with the active chemoautotrophic microbes. In incubations with only H13CO3- (and 15N- ammonium) addition (nr5), fatty acid 16:2 had the highest percent of label uptake (~25%). 16:1, 18:u and 14:1 all had >20% 13C incorporation. Other fatty acids with moderate (5-15%) 13C uptake include 12:0, 14:0 16:0, 18:1?w7. Very low uptake was observed in i-15:0, a15:0; 15:0, 18:1?w9, and 18:0 were all present but did not incorporate detectable 13C. In incubations with thiosulfate added with the H13CO3- (and 15N- ammonium; nr7), the total amount of fatty acids was at least 4x greater. There was also both a shift in the distribution of fatty acids incorporating the label and an increase in the total amount of label incorporation. Fatty acids with >30% 13C include 12:0, 14:1, 14:0, 2 isomers of 16:1, 18:u, and 18:w7. 16:0 also incorporated 13C (~28%). As in nr5, 15:0, a15:0; 15:0, 18:1w9 and 18:0 were all present but showed no 13C enrichment. The labeled fatty acids are consistent with production by sulfur oxidizers. 13C labeled carbon was incorporated into a suite of fatty acids known to be produced by sulfur oxidizers (e.g. Thioploca); production of these lipids also appears to be stimulated with the addition of thiosulfate. On-going work will analyze the phylogenetic affiliations of 13C and 15N labeled DNA, and future experiments will include other potential electron donors and acceptors.

Turich, C.; Taylor, G.; Podlaska, A.; Wakeham, S. G.

2007-12-01

289

Priming effects of biochar elucidated using stable isotope techniques.  

NASA Astrophysics Data System (ADS)

Organic residues are routinely used in tropical agricultural systems; as mulches to reduce water losses and for their fertiliser value. The addition of high N content organic residues to soils has been promoted in tropical countries as a means to achieve sustainable intensification of tropical farming systems and increasing soil organic matter status on infertile low income farms. Improving the nutrient release from these materials could have positive feedback effects in terms of improved food security and increased organic matter return to the soil through improved crop yields. Unfortunately the fertiliser value of most organic residues is such that only 10 -20% of the available nitrogen in the residue is mineralised to plant available nitrogen and taken up by the plant in the first cropping year, dropping to less than 2% in the subsequent years; thus having marginal overall impact on crop yields. Improving the fertiliser benefit of residues by combining them with the biochar addition could lead to significant increases in crop yields, an immediately tangible benefit for farmers. The addition of charcoal in boreal forest systems has been shown to increase the rate of soil organic matter decomposition, suggesting there is a priming effect of a biochar analogue on organic matter decomposition. The priming effect is the increase in soil organic matter (SOM) decomposition rate after the addition of fresh organic matter or other compounds to soil. The implication is that is biochar if addition leads to the loss of native SOM it negates the carbon benefit of adding biochar to soil. However there could also be potential benefits of priming effects of biochar under specific circumstances, for example if biochar addition leads to the priming of freshly added organic matter breakdown it may in turn improve nutrient synchronisation and overall nutrient use efficiency. We conducted a series of experiments conducted in Kenya and Austria using stable isotope tools to look at the priming effects of biochar on the carbon and nitrogen turnover of organic residues added to soils. I will present the finding of these investigations and discuss their implications. Please fill in your abstract text.

Hood-Nowotny, R.; Vanlauwe, B.

2012-04-01

290

LIGHT ISOTOPE ABUNDANCES IN SOLAR ENERGETIC PARTICLES MEASURED BY THE SPACE INSTRUMENT NINA  

E-print Network

LIGHT ISOTOPE ABUNDANCES IN SOLAR ENERGETIC PARTICLES MEASURED BY THE SPACE INSTRUMENT NINA A source of 3He. The presence of such reactions was independently confirmed by the detection of the 2.2 Me was detected by many observers, solar deu- terium and tritium have proved to be very rare and difficult

Morselli, Aldo

291

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

Microsoft Academic Search

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

Tyler B. Coplen; Robert N. Clayton

1973-01-01

292

Combined element (H and C) stable isotope ratios of methane in carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

We have performed the first ever combined-element stable isotopic measurements of extraterrestrial molecules. Methane from two carbonaceous chondrites, Murchison and Cold Bokkeveld, was measured for its hydrogen and carbon isotopic compositions. The combined isotopic composition of meteoritic methane reveals information about the indigenous nature of volatile aliphatic organic matter in meteorites and its probable extraterrestrial source environment. Deuterium enrichments relative to the solar nebula 4.6 Gyr ago reflect a contribution from low-temperature chemical reactions in interstellar space. Similar carbon but different hydrogen isotopic compositions for methane in the two meteorite samples probably represent comparable primary origins but varying levels of secondary processing and exchange with isotopically light hydrogen. Our high precision laboratory-obtained measurements provide valuable reference points for observational spectroscopists undertaking astronomical investigations of the stable isotopic composition of extraterrestrial methane.

Butterworth, Anna L.; Aballain, Olivier; Chappellaz, Jerome; Sephton, Mark A.

2004-01-01

293

Stable isotope analysis of the origins of zooplankton carbon in lakes of differing trophic state  

Microsoft Academic Search

Carbon stable isotope analysis was carried out on zooplankton from 24 United Kingdom lakes to examine the hypothesis that\\u000a zooplankton dependence on allochthonous sources of organic carbon declines with increasing lake trophy. Stable isotope analysis\\u000a was also carried out on particulate and dissolved organic matter (POM and DOM) and, in 11 of the lakes, of phytoplankton isolates.\\u000a In 21 of

Jonathan Grey; Roger I. Jones; Darren Sleep

2000-01-01

294

Using stable-isotope analysis of feathers to distinguish moulting and breeding origins of seabirds  

Microsoft Academic Search

To determine whether stable isotope measurements of bird feathers can be used to identify moulting (interbreeding) foraging\\u000a areas of adult seabirds, we examined the stable-carbon (?13C) and nitrogen (?15N) isotopic composition of feathers of chicks and adults of black-browed albatrosses (Diomedea melanophrys) from Kerguelen Islands, southern Indian Ocean. Albatross chicks are fed primarily fish (75% by mass), the diet being

Yves Cherel; Keith A. Hobson; Henri Weimerskirch

2000-01-01

295

The requirement for accurate diet-tissue discrimination factors for interpreting stable isotopes in sharks  

Microsoft Academic Search

Stable isotopes of nitrogen and carbon (?15N and ?13C) provide an important tool to examine diet, trophic position and movement\\/migration of both aquatic and terrestrial animals.\\u000a Over the past 10years, there have been repeated calls to tighten up basic assumptions when applying stable isotopes, one\\u000a of the most important being the application of accurate, species-specific diet-tissue discrimination factors (DTDFs). Taxa-

Nigel E. HusseyM; M. Aaron MacNeil; Aaron T. Fisk

2010-01-01

296

Stable carbon isotopes as an indicator of petroleum biodegradation in estuarine sediments  

E-print Network

STABLE CARBON ISOTOPES AS AN INDICATOR OF PETROLEUM BIODEGRADATION IN ESTUARINE SEDIMENTS A Thesis by DEBORAH LOUISE HESSE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE May 1994 Major Subject: Oceanography STABLE CARBON ISOTOPES AS INDICATORS OF PETROLEUM BIODEGRADATION IN ESTUARINE SEDIMENTS A Thesis by DEBORAH LOUISE HESSE Submitted to Texas A8 M University in partial fulfillment...

Hesse, Deborah Louise

2012-06-07

297

Determination of 235U isotopic abundance by fission-yield difference method  

NASA Astrophysics Data System (ADS)

Based on neutron activation analysis, a new method was presented for the determination of uranium isotopic abundance, in which fast neutrons generated by T (d, n) 4He were used to induce fission in uranium samples. The exponential relation between different abundances of 235U and the average fission-yield ratios of specific fission products was employed in this method. Taking the fission-yield ratios of specific fission products, such as Y/, Y/, Y/ and Y/ as the subjects of research, the relation curves between the average yield ratios and the 235U isotopic abundance as well as the expressions (Y/Y=f(H0)) for the average yield ratio (Y/Y) as a function of the 235U isotopic abundance (H0) were obtained. To verify the precision and accuracy of this method, 5 tests using each working curve were conducted for simulated samples with a 235U abundance of 72.2%, and the relative standard deviation (RSD) of all tests was less than 2%. Compared to the ? energy spectrum method, the relative error of each measurement result was between 1.11% and 1.66%.

Qiao, Yahua; Zhang, Ming; Yang, Yi; Liu, Shilong; Wu, Jizong; Wang, Bo

2014-03-01

298

Late Quaternary Precipitation Seasonality of SW North America Reconstructed from Stable Isotopes in Fossil Packrat Pellets  

NASA Astrophysics Data System (ADS)

Stable isotopic values of Carbon 13, Nitrogen 15, Oxygen 18, and Deuterium were measured from modern and fossil packrat pellets from throughout the southwestern United States using a gas isotope ratio mass spectrometer. Late Twentieth Century climate observations were extrapolated to the locations of 41 modern pellet reference samples ranging across Arizona, Utah, Nevada, and California, U.S.A. The reference samples demonstrated correlations between the amount and percent of annual precipitation falling in the winter to early spring (December through April) for ?15N, and percent monsoon precipitation (July through September) for ?D. Isotope values were not well correlated with temperature variables. Isotopes of Carbon and Oxygen were poorly correlated with the climate variables investigated, although previous studies have indicated that ?13C often reflects the abundance of CAM species within the middens as packrats usually feed upon either succulent CAM or C3 conifer species. The modern isotopic values were next compared to series of fossil values from the Grand Canyon, AZ, Glen Canyon, UT, Wupatki National Monument, AZ, and Picacho Peak, CA. Fifty to 100 fossil pellets were ground to dust and homogenized to create a sample from each midden deposit. This sample should represent an average from local plants consumed by the packrat over at least several years. The two most complete series of ?D values, from upper and lower elevations within the Grand Canyon, suggested extremely low monsoon percentages from 23.5 to 18.0 ka (full-glacial Wisconsinan), but higher than current values from 13.7 to 13.0 ka (Allerd Period) and from 11.7 to 7.6 ka (early Holocene). The increased monsoon amounts during the Allerd and early Holocene reinforce earlier conclusions based upon plant fossils from these midden series. Fossil series of ?15N values showed fewer clear trends through time. Our results suggest that ?D values from fossil packrat pellets can serve as a valuable complement to plant fossils in reconstructing past precipitation seasonality in the monsoonal deserts of southwestern North America.

Cole, K. L.; Ironside, K.; Cole, E. A.; Fisher, J.

2011-12-01

299

Assessment of the Authenticity of Fruit Spirits by Gas Chromatography and Stable Isotope Ratio Analyses  

Microsoft Academic Search

Winterov R., Mikulkov R., Maz? J., Havelec P. (2008): Assessment of the authenticity of fruit spirits by gas chromatography and stable isotope ratio analyses. Czech J. Food Sci., 26: 368-375. The gas chromatographic (GC) determination of volatile constituents and the determination of 13C\\/12C isotope ratios by isotope ratio mass spectrometry - IRMS analysis as well as SNIF-NMR analysis of (D\\/H)I

Renata WINTEROV; Renata MIKULKOV; Pavel HAVELEC

300

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

Microsoft Academic Search

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

Thomas J. Kwak; Joy B. Zedler

1997-01-01

301

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

E-print Network

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

Zare, Richard N.

302

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

NASA Astrophysics Data System (ADS)

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. Ct (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 (20

Barras, Vaughan; Simmonds, Ian

2010-05-01

303

Feathers as a means of monitoring mercury in seabirds: Insights from stable isotope analysis  

Microsoft Academic Search

Mercury concentrations, together with nitrogen and carbon stable isotope signatures, were determined in body feather samples from northern fulmars Fulmarus glacialis and great skuas Catharacta skua, and in different flight feathers from great skuas. There were no significant relationships between trophic status, as defined using isotope analysis, and mercury concentration in the same feather type, in either species. Mercury concentrations

D. R Thompson; S Bearhop; J. R Speakman; R. W Furness

1998-01-01

304

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...

305

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

SciTech Connect

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

Ruwe, Jr, A H [comp.

1982-10-01

306

Tracking Trophic Interactions in Coldwater Reservoirs Using Naturally Occurring Stable Isotopes  

Microsoft Academic Search

We measured signatures of naturally occurring stable isotopes of carbon (13C) and nitrogen (15N) in important invertebrate and fish taxa in two coldwater reservoirs in Colorado that had different food webs. One reservoir, Lake Granby, contained a large population of an opossum shrimp, Mysis relicta, and the other, Blue Mesa Reservoir, did not. We compared temporal dynamics of isotopic signatures

Brett M. Johnson; Patrick J. Martinez; Jason D. Stockwell

2002-01-01

307

Stable hydrogen isotopic composition of fishes reflects that of their environment  

Microsoft Academic Search

Otolith microchemistry and isotopic analyses have emerged as effective techniques for providing insights into fish environmental history that are difficult to obtain by other means. Stable hydrogen isotope ratio (2H\\/1 Ho r D\\/H, expressed as ?D) is a possible environmental marker that has not been employed in fish provenance research, although it has been applied as a natural tracer of

Gregory W. Whitledge; Brett M. Johnson; Patrick J. Martinez

2006-01-01

308

Stable carbon and oxygen isotopes in Sphagnum fuscum peat from subarctic Canada: Implications for palaeoclimate studies  

Microsoft Academic Search

Stable carbon and oxygen isotope ratios in single plant components in Sphagnum peat have a good potential to reveal environmental changes in peat archives. Two peat profiles, covering the past ?6000years, and a Sphagnum hummock from a discontinuous permafrost area in west central Canada were studied in order to evaluate the effect of decomposition rate on isotope records and to

Pivi Kaislahti Tillman; Steffen Holzkmper; Peter Kuhry; A. Britta K. Sannel; Neil J. Loader; Iain Robertson

2010-01-01

309

CHERNOBYL AS A POPULATION SINK FOR BARN SWALLOWS: TRACKING DISPERSAL USING STABLE-ISOTOPE PROFILES  

Microsoft Academic Search

Stable-isotope profiles of feathers can reveal the location or habitat used by individual birds during the molting period. Heterogeneity in isotope profiles will reflect heterogeneity in molt locations, but also heterogeneity in breeding locations, because spatial heterogeneity in molt locations will be congruent with spatial heterogeneity in breeding locations in species with high connectivity between breeding and molting sites. We

A. P. Mller; K. A. Hobson; T. A. Mousseau; A. M. Peklo

2006-01-01

310

Stable isotope sales: Mound Laboratory customer and shipment summaries, FY 1973  

Microsoft Academic Search

A listing is given of Mound Laboratory's sales of stable isotopes of ; noble gases, carbon, oxygen, and nitrogen, for Fiscal Year 1973. Purchasers are ; listed alphabetically and are divided into domestic and foreign groups. A cross-; reference index by location is included for domestic customers. Cross-referenced ; listings by isotope purchased are included for all customers. (auth)

Stringham

1973-01-01

311

Stable isotope sales: Mound Laboratory customer and shipment summaries, FY1975  

Microsoft Academic Search

A listing is given of Mound Laboratory's sales of stable isotopes of noble gases, carbon, oxygen, nitrogen, and sulfur for Fiscal Year 1975. Purchasers are listed alphabetically and are divided into domestic and foreign groups. A cross reference index by location is included for domestic customers. Cross reference listings by isotope purchased are included for all customers.

Eck

1976-01-01

312

ENRICHED STABLE ISOTOPE TARGET PREPARATION AT THE OAK RIDGE NATIONAL LABORATORY  

SciTech Connect

Since the 1960s the Department of Energy (DOE) Isotope Program, through the Isotope Development Group at the Oak Ridge National Laboratory, has been developing and supplying, among other things, enriched stable isotope targets for nuclear research around the world. This group also maintains and distributes the DOE inventory of enriched stable isotopes. Chemical and pyrochemical techniques are used to prepare enriched stable isotopes from this inventory in the desired chemical form. Metallurgical, ceramic, or vacuum processing methods are then used to prepare the isotopes in a wide range of physical forms from thin films, foils, and coatings to large fabricated shapes to meet the needs of experimenters. Significant characterization capabilities are also available to assist in the preparation and evaluation of these custom materials. This work is part of the DOE Isotope Program, which recently transferred to the Office of Nuclear Physics, DOE Office of Science, resulting in a stronger emphasis on enabling R&D. This presentation will focus on the custom preparation of enriched stable isotope targets and other research materials.

Aaron, W Scott [ORNL] [ORNL; Zevenbergen, Lee [ORNL] [ORNL

2013-01-01

313

Tracking Trophic Interactions in Coldwater Reservoirs Using Naturally Occurring Stable Isotopes  

Microsoft Academic Search

We measured signatures of naturally occurring stable isotopes of carbon (C) and nitrogen (N) in important invertebrate and fish taxa in two coldwater reservoirs in Colorado that had different food webs. One reservoir, Lake Granby, contained a large population of an opossum shrimp, Mysis relicta, and the other, Blue Mesa Reservoir, did not. We compared temporal dynamics of isotopic signatures

Brett M. Johnson; Patrick J. Martinez; Jason D. Stockwell

2002-01-01

314

Magnetic moment measurements - extending isotopic chains beyond the stable elements  

NASA Astrophysics Data System (ADS)

The magnetic moments in many isotopic chains have been systematically measured using the transient field technique on beams of separated isotopes excited in inverse kinematics. Such experiments have provided insight into how the structure of nuclei evolves by successively adding nucleons. Since naturally occurring isotopic chains are relatively short, efforts are underway to make unstable isotopes available. In limited cases the use of an a-particle transfer to beam projectiles has been successfully employed in measurements on unstable nuclei. In this investigation beams of 78Kr and 86Kr were used to measure magnetic moments of excited states in the unstable 82 Sr and 90 Sr nuclei utilizing the transfer of an ? particle from 12 C nuclei in the target.

Kumbartzki, G. J.

2014-09-01

315

Stable-isotope geochronology of the Australian regolith  

SciTech Connect

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

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

1989-12-01

316

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

PubMed

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

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

1990-01-01

317

Origin of petroporphyrins. 2. Evidence from stable carbon isotopes  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

318

Stable carbon and nitrogen isotope enrichment in primate tissues  

Microsoft Academic Search

Isotopic studies of wild primates have used a wide range of tissues to infer diet and model the foraging ecologies of extinct\\u000a species. The use of mismatched tissues for such comparisons can be problematic because differences in amino acid compositions\\u000a can lead to small isotopic differences between tissues. Additionally, physiological and dietary differences among primate\\u000a species could lead to variable

Brooke E. Crowley; Melinda L. Carter; Sarah M. Karpanty; Adrienne L. Zihlman; Paul L. Koch; Nathaniel J. Dominy

2010-01-01

319

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

E-print Network

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

Alan P. Boss

2007-02-02

320

Use of stable isotopic selenium as a tracer to follow incorporation of selenium into selenoproteins  

SciTech Connect

Stable isotopes of selenium (Se) have been used in human studies to measure Se absorption, retention and excretion. The purpose of this study was to examine whether stable Se could also be used to follow the incorporation of Se into selenoproteins and whether selenoproteins are labeled with stable isotopes the same way they are with radioactive Se. Rats fed either a Se-deficient or a high-Se diet were injected with either a radioactive ({sup 75}Se) or a stable isotope of Se ({sup 77}Se), and the liver cytosol was chromatographed on Sephadex G-200. Compared with {sup 75}Se, a greater percentage of {sup 77}Se was incorporated into cytosol, but the distribution and the effect of dietary Se was similar for both isotopes. New Zealand long-eared rabbits were also injected with either {sup 77}Se or {sup 75}Se, and the plasma was chromatographed. More of the {sup 75}Se was incorporated into the plasma, but again the patterns of incorporation were similar for both isotopes. Plasma from a male subject who ingested 60 {mu}g of {sup 77}Se was chromatographed, and the stable Se was detected in column fractions and showed a distribution similar to that observed for rabbit plasma. Finally, a polyacrylamide gel electrophoresis (PAGE) method was developed that allowed loading of sufficient protein to analyze for {sup 77}Se in individual protein fractions. The distribution of {sup 77}Se and {sup 75}Se in rabbit plasma was similar. Human plasma was electrophoresed by a similar method and peaks of 56 and 23 kDa were detected. These data show that stable isotopes of Se can be used for selenoprotein production in the same way as radioactive isotopes. They also show that, when physiological amounts of stable Se are ingested by humans, the isotope can be detected in blood-borne proteins separated by column chromatography and PAGE. 28 refs., 5 figs.

Finley, J.W.; Vanderpool, R.A.; Korynta, E. [Grand Forks Human Nutrition Research Center, ND (United States)

1995-12-01

321

Population-Level Metrics of Trophic Structure Based on Stable Isotopes and Their Application to Invasion Ecology  

PubMed Central

Biological invasions are a significant driver of human-induced global change and many ecosystems sustain sympatric invaders. Interactions occurring among these invaders have important implications for ecosystem structure and functioning, yet they are poorly understood. Here we apply newly developed metrics derived from stable isotope data to provide quantitative measures of trophic diversity within populations or species. We then use these to test the hypothesis that sympatric invaders belonging to the same functional feeding group occupy a smaller isotopic niche than their allopatric counterparts. Two introduced, globally important, benthic omnivores, Louisiana swamp crayfish (Procambarus clarkii) and carp (Cyprinus carpio), are sympatric in Lake Naivasha, Kenya. We applied our metrics to an 8-year data set encompassing the establishment of carp in the lake. We found a strong asymmetric interaction between the two invasive populations, as indicated by inverse correlations between carp abundance and measures of crayfish trophic diversity. Lack of isotopic niche overlap between carp and crayfish in the majority of years indicated a predominantly indirect interaction. We suggest that carp-induced habitat alteration reduced the diversity of crayfish prey, resulting in a reduction in the dietary niche of crayfish. Stable isotopes provide an integrated signal of diet over space and time, offering an appropriate scale for the study of population niches, but few isotope studies have retained the often insightful information revealed by variability among individuals in isotope values. Our population metrics incorporate such variation, are robust to the vagaries of sample size and are a useful additional tool to reveal subtle dietary interactions among species. Although we have demonstrated their applicability specifically using a detailed temporal dataset of species invasion in a lake, they have a wide array of potential ecological applications. PMID:22363724

Jackson, Michelle C.; Donohue, Ian; Jackson, Andrew L.; Britton, J. Robert; Harper, David M.; Grey, Jonathan

2012-01-01

322

Population-level metrics of trophic structure based on stable isotopes and their application to invasion ecology.  

PubMed

Biological invasions are a significant driver of human-induced global change and many ecosystems sustain sympatric invaders. Interactions occurring among these invaders have important implications for ecosystem structure and functioning, yet they are poorly understood. Here we apply newly developed metrics derived from stable isotope data to provide quantitative measures of trophic diversity within populations or species. We then use these to test the hypothesis that sympatric invaders belonging to the same functional feeding group occupy a smaller isotopic niche than their allopatric counterparts. Two introduced, globally important, benthic omnivores, Louisiana swamp crayfish (Procambarus clarkii) and carp (Cyprinus carpio), are sympatric in Lake Naivasha, Kenya. We applied our metrics to an 8-year data set encompassing the establishment of carp in the lake. We found a strong asymmetric interaction between the two invasive populations, as indicated by inverse correlations between carp abundance and measures of crayfish trophic diversity. Lack of isotopic niche overlap between carp and crayfish in the majority of years indicated a predominantly indirect interaction. We suggest that carp-induced habitat alteration reduced the diversity of crayfish prey, resulting in a reduction in the dietary niche of crayfish. Stable isotopes provide an integrated signal of diet over space and time, offering an appropriate scale for the study of population niches, but few isotope studies have retained the often insightful information revealed by variability among individuals in isotope values. Our population metrics incorporate such variation, are robust to the vagaries of sample size and are a useful additional tool to reveal subtle dietary interactions among species. Although we have demonstrated their applicability specifically using a detailed temporal dataset of species invasion in a lake, they have a wide array of potential ecological applications. PMID:22363724

Jackson, Michelle C; Donohue, Ian; Jackson, Andrew L; Britton, J Robert; Harper, David M; Grey, Jonathan

2012-01-01

323

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

Microsoft Academic Search

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

Paul R. Carlson; Joseph Forrest

1982-01-01

324

Stable isotopes applied as water tracers in column and field studies  

Microsoft Academic Search

The stable isotopes deuterium (2H, D) and oxygen 18 (18O) were applied in water for use as tracers in column experiments and in two field studies. Their performance was compared against uranine and was used to characterize saturated and unsaturated water movement and depths of plant water uptake. Deuterium and 18O are completely soluble and chemically and biologically stable. They

Paul Koeniger; Christian Leibundgut; Timothy Link; John D. Marshall

2010-01-01

325

Selenium Concentrations and Stable Isotopic Compositions of Carbon and Nitrogen in the  

E-print Network

Selenium Concentrations and Stable Isotopic Compositions of Carbon and Nitrogen in the Benthic Clam of the Interior U.S. Geological Survey Open-File Report 2010­1252 #12;#12;Selenium Concentrations and Stable://store.usgs.gov Suggested citation: Kleckner, A.E., Stewart, A.R., Elrick, K., and Luoma, S.N., 2010, Selenium

326

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...

327

The use of carbon stable isotope ratios in drugs characterization  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

328

The use of carbon stable isotope ratios in drugs characterization  

SciTech Connect

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

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

2013-11-13

329

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

NASA Astrophysics Data System (ADS)

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

Werner, C.; Schnyder, H.; Cuntz, M.; Keitel, C.; Zeeman, M. J.; Dawson, T. E.; Badeck, F.-W.; Brugnoli, E.; Ghashghaie, J.; Grams, T. E. E.; Kayler, Z. E.; Lakatos, M.; Lee, X.; Mguas, C.; Oge, J.; Rascher, K. G.; Siegwolf, R. T. W.; Unger, S.; Welker, J.; Wingate, L.; Gessler, A.

2012-08-01

330

Fluid inclusion stable isotopes and clumped isotopes thermometry study of Eastern Mediterranean paleoclimate  

NASA Astrophysics Data System (ADS)

Fluid inclusion (FI) stable isotopes and clumped isotopes thermometry provide powerful tools for reconstructing paleoclimates using speleothems. Clumped isotopes thermometry is a unique tool for paleotemperature determination using the mass 47 anomaly (?47), but its application to speleothems is complicated by the occurrence of a kinetic isotope effect (KIE) that accompanies CO2 degassing during carbonate precipitation1. Experimental studies involving the surface precipitation of synthetic calcite2 provide a ?47 thermometer calibration that takes KIE into account and allows its direct application to speleothems. Complementary, the ?Dw and ?18Ow values of speleothem FI provide an important proxy for cave water-rainfall paleo-hydrological conditions, together with the data required for construction of the meteoric water line (MWL) relationship. Until recently the main studied parameter is ?Dw, and the reliability of FI ?18Ow has been questioned because of the possibility of post-depositional isotope exchange with the surrounding calcite. When speleothem calcite ?18Occ is measured, ?47 temperatures allow ?18Ow to be independently calculated using the calcite-water fractionation relationship. Methods for FI analysis using crushing in a helium stream, TC/EA and continuous flow mass spectrometry (Amsterdam system3) enable both ?Dw and ?18Ow to be determined, thus allowing measured ?18Ow values to be compared with those calculated from ?47 temperatures and ?18Occ. We apply these methodologies to paleoclimate study in the Eastern Mediterranean (EM) region during the last 150 ky: in the Soreq Cave from the glacial stage 6 to the last interglacial stage 5e and the last glacial maximum (LGM) to the Holocene, and to the Alpine karst system of the Hermon mountain range (MS) cave4 during the last interglacial and brief warm intervals during the last glacial. Soreq Cave ?47 data show temperature minima at the termination of stage 6 and the LGM, but the LGM temperatures (ca 9 C) were several degrees lower than for glacial stage 6. Both minima were followed by sharp temperature rises into stage 5e and Holocene, respectively. ?47 thermometry of the MS cave speleothems confirm that temperatures rose to several degrees above freezing during brief warming events in the otherwise frozen last glacial at this altitude (2224m). MWL relationships over the last 150 ky using FI ?Dw and calculated ?18Ow suggest that glacial periods are characterized by a MWL closer to that of the global system, whereas interglacial periods in the Soreq cave and warm glacial intervals in the MS cave show higher "d excesses" characteristic of the present day EM region. The MWL relationships of Soreq Cave speleothems in stage 5e are consistent with the 'amount effect' controlling ?18Ow, as found today and in the Holocene5. Comparison of measured with calculated ?18Ow values show that it may also be possible to retrieve accurate values for ?18Ow in suitable speleothems. 1. Affek, H., et al (2008). Geochim. Cosmochim. Acta 72, 5351-5360. 2. Zaarur, S. and Affek, H. In preparation. 3. Vonhof, H., et al. (2006). Rapid Comm. Mass Spectrom. 20, 2553-255. 4. Ayalon et al (2012) In submission. 5. Bar Matthews, M., et al (2003). Geochim. Cosmochim. Acta 67, 3181-3199.

Matthews, A.; Bar-Matthews, M.; Affek, H. P.; Ayalon, A.; Vonhof, H. B.; Zaarur, S.; Burstyn, Y.

2012-04-01

331

Stable isotope analysis of Pacific salmon: insight into trophic status and oceanographic conditions over the last 30 years  

NASA Astrophysics Data System (ADS)

Food web interactions and the response of Pacific salmon to physical processes in the North Pacific Ocean over interannual and interdecadal timescales are explored using naturally occurring stable isotope ratios of carbon ( 13C/ 12C) and nitrogen ( 15N/ 14N). Stable isotope analyses of five species of sexually mature North Pacific salmon from Alaska ( Oncorhynchus spp.) cluster into three groups: chinook salmon ( O. tshawytscha) have the highest values, followed by coho ( O. kisutch), with chum ( O. keta), sockeye ( O. nerka), and pink ( O. gorbuscha) together having the lowest values. Although detailed isotopic data on salmon prey are lacking, there are limited data on relevant prey items from areas in which they are found in high abundance. These data suggest that the characteristics of the sockeye, pink and chum we have analyzed are compatible with their diets including open ocean squid and zooplankton, which are in general agreement with stomach content analyses. Isotope relationships between muscle and scale show consistent relationships for both ?13C ( R2=0.98) and ? 15N ( R2=0.90). Thus, scales, which have been routinely archived for many systems, can be used for retrospective analyses. Archived sockeye salmon scales spanning 1966-1999 from Red Lake, Kodiak Island, Alaska were analyzed for their stable isotope ratios of carbon and nitrogen. The ?15N record displays a decreasing trend of ~3 from 1969-1982 and an increasing trend of ~3 from 1982-1992, while the variations in ?13C are relatively minor. These trends may result from factors such as shifts in trophic level of feeding and/or feeding location, or may originate at the base of the food web via changes in processes such as nutrient cycling or primary productivity. Detailed studies on prey isotopic variability and its controls are needed to distinguish between these factors, and thus to improve the use of stable isotope analysis as a tool to learn more about present and past ecosystem change in the North Pacific and its relation to climatic change.

Satterfield, Franklin R.; Finney, Bruce P.

332

Stable carbon isotope fractionation by sulfate-reducing bacteria  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

333

Photosynthetic fractionation of the stable isotopes of oxygen and carbon  

SciTech Connect

Isotope discrimination during photosynthetic exchange of O[sub 2] and CO[sub 2] was measured using enzyme, thylakoid, and whole cell preparations. Evolved oxygen from isolated spinach thylakoids was isotopically identical (within analytical error) to its source water. Similar results were obtained with Anacystis nidulans Richter and Phaeodactylum tricornutum Bohlin cultures purged with helium. For consumptive reactions, discrimination ([triangle], where 1 + [triangle]/1000 equals the isotope effect, k[sup 16]/k[sup 18] or k[sup 12]/k[sup 13]) was determined by analysis of residual substrate (O[sub 2] or CO[sub 2]). The [triangle] for the Mehler reaction, mediated by ferredoxin or methylviologen, was 15.3[per thousand]. Oxygen isotope discrimination during oxygenation of ribulose-1,5-bisphosphate (RuBP) catalyzed by RuBP carboxylase/oxygenase (Rubisco) was 21.3[per thousand] and independent of enzyme source, unlike carbon isotope dicrimination: 30.3[per thousand] for spinach enzyme and 19.6 to 23[per thousand] for Rhodospirillum rubrum and A. nidulans enzymes, depending on reaction conditions. The [triangle] for O[sub 2] consumption catalyzed by glycolate oxidase was 22.7[per thousand]. Consistent with this, when Asparagus sprengeri Regel mesopyll cells approached the compensation point within a sealed vessel, the [delta][sup 18]O of dissolved O[sub 2] came to a steady-state value of about 21.5[per thousand] relative to the source water. The results provide improved estimates of discrimination factors in several reactions prominent in the global oxygen cycle and indicate that photorespiration plays a significant part in determining the isotopic composition of atmospheric oxygen. 47 refs., 8 figs., 2 tabs.

Guy, R.D. (Carnegie Institution of Washington, Stanford, CA (United States)); Fogel, M.L.; Berry, J.A. (Carnegie Inst. of Washington, Washington, DC (United States))

1993-01-01

334

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

SciTech Connect

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

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

2012-01-03

335

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

SciTech Connect

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

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

2012-01-01

336

Calibrated sulfur isotope abundance ratios of three IAEA sulfur isotope reference materials and V-CDT with a reassessment of the atomic weight of sulfur  

Microsoft Academic Search

Calibrated values have been obtained for sulfur isotope abundance ratios of sulfur isotope reference materials distributed by the IAEA (Vienna). For the calibration of the measurements, a set of synthetic isotope mixtures were prepared gravimetrically from high purity Ag2S materials enriched in32S, 33S, and 34S. All materials were converted into SF6 gas and subsequently, their sulfur isotope ratios were measured

T. Ding; S. Valkiers; H. Kipphardt; P. De Bivre; P. D. P. Taylor; R. Gonfiantini; R. Krouse

2001-01-01

337

Trophic ecology of marine birds and pelagic fishes from Reunion Island as determined by stable isotope analysis  

E-print Network

isotope analysis Jessica Kojadinovic1,2,3, *, Frédéric Ménard4 , Paco Bustamante1 , Richard P. Cosson2-251" DOI : 10.3354/meps07355 #12;ABSTRACT: Stable nitrogen and carbon isotopes were used to investigate and complementary approach to these methods is the measurement of naturally occurring stable isotopes in consumers

Paris-Sud XI, Université de

338

Characterizing the Distribution of Methane Sources and Cycling in the Deep Sea via in Situ Stable Isotope Analysis  

E-print Network

Isotope Analysis Scott D. Wankel,*,, Yi-wen Huang,, Manish Gupta,§ Robert Provencal,§ J. Brian Leen to make in situ geo-referenced measurements of methane concentration and stable isotopic composition (13 and provide the first in situ stable isotope based characterization of the influence of anaerobic methane

Girguis, Peter R.

339

Using Stable Isotope Analysis to Obtain Dietary Profiles From Old Hair: A Case Study From Plains Indians  

E-print Network

Using Stable Isotope Analysis to Obtain Dietary Profiles From Old Hair: A Case Study From Plains been used much more often than hair in stable isotope analysis to infer diet. Published work on hair Station, Texas 77893 KEY WORDS nitrogen; carbon; isotope ratios; mass spectrometry; diet; hair analysis

Kurapov, Alexander

340

Stable water isotope characterization of human and natural impacts on land-atmosphere exchanges in the Amazon Basin  

Microsoft Academic Search

Stable water isotopes have been employed as a means of challenging, validating, and improving numerical models of the Amazon Basin since the 1980s. This paper serves as an exemplar of how characterization of human and natural impacts on surface-atmosphere water exchanges could beneficially exploit stable water isotope data and simulations. Interpretations of Amazonian isotopic data and model simulations are found

K. McGuffie; A. Henderson-Sellers

2004-01-01

341

Stable carbon isotope values document how a Late Holocene expansion in grasslands impacted vertebrates in northwestern Madagascar  

NASA Astrophysics Data System (ADS)

Madagascar is home to some of the world's most distinctive plants and animals. Unfortunately, forest loss and habitat degradation has had a dramatic impact on both floral and faunal communities. Here we use carbon isotope values in radiocarbon-dated bones to examine how the vertebrate community at Anjohibe Cave, northwestern Madagascar, responded to a Late Holocene increase in C4 grass abundance. Our data demonstrate that major changes in the vegetation and animal community are recent phenomena at Anjohibe. Extinct lemurs and hippopotamuses were present until ca. 1500 years ago. These taxa relied exclusively on C3 resources. Locally extirpated fauna were present until 300 years ago. The majority of these species also relied on C3 resources. Their presence strongly suggests that the region surrounding the cave was more wooded than it is now, possibly as recently as 300 years ago. All introduced individuals are modern. Rats (Rattus sp.), shrews (Suncus murinus), and the giant frog Hoplobatrachus cf. tigrinus, have remarkably high carbon isotope values, implicating substantial ingestion of C4 foods. It is possible that grass abundance has increased dramatically in the past 100 years. Alternatively, opportunistically granivorous rats and shrews may selectively consume seeds from C4 grasses. In agreement with previous studies, stable isotope data reveal details of vegetation and faunal turnover in Northwestern Madagascar. Grasses have increased, forest dwelling species have vanished, and introduced taxa are exploiting a novel niche.

Crowley, B. E.; Samonds, K.

2012-12-01

342

Novel and non-traditional use of stable isotope tracers to study metal bioavailability from natural particles  

USGS Publications Warehouse

We devised a novel tracing approach that involves enriching test organisms with a stable metal isotope of low natural abundance prior to characterizing metal bioavailability from natural inorganic particles. In addition to circumventing uncertainties associated with labeling natural particles and distinguishing background metals, the proposed "reverse labeling" technique overcomes many drawbacks inherent to using radioisotope tracers. Specifically, we chronically exposed freshwater snails (Lymnaea stagnalis) to synthetic water spiked with Cu that was 99.4% 65Cu to increase the relative abundance of 65Cu in the snails tissues from 32% to >80%. The isotopically enriched snails were then exposed to benthic algae mixed with Cu-bearing FeAl particles collected from the Animas River (Colorado), an acid mine drainage impacted river. We used 63Cu to trace Cu uptake from the natural particles and inferred their bioavailability from calculation of Cu assimilation into tissues. Cu assimilation from these particles was 44%, indicating that 44% of the particulate Cu was absorbed by the invertebrate. This demonstrates that inorganic particulate Cu can be bioavailable. The reverse labeling approach shows great potential in various scientific areas such as environmental contamination and nutrition for addressing questions involving uptake of an element that naturally has multiple isotopes.

Croteau, Marie-Noele; Cain, Daniel J.; Fuller, Christopher C.

2013-01-01

343

STABLE CHLORINE ISOTOPE ANALYSIS OF CHLORINATED ORGANIC CONTAMINANTS  

EPA Science Inventory

The biogeochemical cycling of chlorinated organic contaminants in the environment is often difficult to understand because of the complex distributions of these compounds and variability of sources. To address these issues from an isotopic perspective, we have measured the, 37Cl...

344

Stable isotope geochemistry of fumaroles: an insight into volcanic surveillance  

NASA Astrophysics Data System (ADS)

In active volcanic environments magmatic water may accumulate in the volcanic-hosted geothermal systems, or, more rarely may reach the surface along deep fractures inside the volcano crater. Knowledge of magmatic contribution to emerging fluids in volcanic active areas is critical to understanding the chemical evolution of the magma, the conditions in which it exists in the crust, and the mechanisms by which it erupts in the crust. The source of volatiles (especially water) is also of interest when eruptions are driven by the expansion of hydrothermal fluids against atmospheric pressure, without the involvement of fresh magma ('hydrothermal' or 'phreatomagmatic' eruptions). In both cases the occurrence of volcanic and/or phreatic activities is likely to be preceded by substantial isotopic and chemical changes in the crater fumarolic systems. H and O isotopic composition of condensed water from crater fumaroles appear to be able to give strong evidence for the existence of magmatic waters in the high-temperature manifestations of the volcanic systems. Isotopic data and specific hydrological models from seven different volcanic systems (Galeras Volcano, Colombia, Kilauea Volcano, Hawaii, Kudryvy Volcano, Kuril volcanic arc, Mt St Helens, USA; Guagua Pichincha, Ecuador; Vulcano island, Italy; the Aegean Volcanic Arc, Greece) are discussed in order to highlight the possibility to use those isotopic parameters in the assessment of the environmental risks of an active volcanic area.

Panichi, C.; La Ruffa, G.

2001-12-01

345

Stable isotope fractionation to investigate natural transformation mechanisms of organic contaminants: principles, prospects and limitations.  

PubMed

Gas chromatography-isotope ratio mass spectrometry (GC-IRMS) has made it possible to analyze natural stable isotope ratios (e.g., (13)C/(12)C, (15)N/(14)N, (2)H/(1)H) of individual organic contaminants in environmental samples. They may be used as fingerprints to infer contamination sources, and may demonstrate, and even quantify, the occurrence of natural contaminant transformation by the enrichment of heavy isotopes that arises from degradation-induced isotope fractionation. This review highlights an additional powerful feature of stable isotope fractionation: the study of environmental transformation mechanisms. Isotope effects reflect the energy difference of isotopologues (i.e., molecules carrying a light versus a heavy isotope in a particular molecular position) when moving from reactant to transition state. Measuring isotope fractionation, therefore, essentially allows a glimpse at transition states! It is shown how such position-specific isotope effects are "diluted out" in the compound average measured by GC-IRMS, and how a careful evaluation in mechanistic scenarios and by dual isotope plots can recover the underlying mechanistic information. The mathematical framework for multistep isotope fractionation in environmental transformations is reviewed. Case studies demonstrate how isotope fractionation changes in the presence of mass transfer, enzymatic commitment to catalysis, multiple chemical reaction steps or limited bioavailability, and how this gives information about the individual process steps. Finally, it is discussed how isotope ratios of individual products evolve in sequential or parallel transformations, and what mechanistic insight they contain. A concluding session gives an outlook on current developments, future research directions and the potential for bridging the gap between laboratory and real world systems. PMID:21038038

Elsner, Martin

2010-11-01

346

Isotopic and elemental abundances of neon nuclei accelerated in solar flares  

Microsoft Academic Search

The relative isotopic abundances of ²°Ne and ²²Ne in seven solar flares were determined from measurements on the satellite IMP 8, yielding the ratio ²°Ne\\/²²Ne=7.7 (+2.3, -1.5) for solar chromospheric matter. This value is in agreement with the ratio for the component Neon-A (the ''primordial'' component) found in carbonaceous chondrites. An elemental abundance ratio Ne\\/O=0.14 +- 0.01 also has been

W. F. Dietrich; J. A. Simpson

1979-01-01

347

Pre-Whaling Genetic Diversity and Population Ecology in Eastern Pacific Gray Whales: Insights from Ancient DNA and Stable Isotopes  

PubMed Central

Commercial whaling decimated many whale populations, including the eastern Pacific gray whale, but little is known about how population dynamics or ecology differed prior to these removals. Of particular interest is the possibility of a large population decline prior to whaling, as such a decline could explain the ?5-fold difference between genetic estimates of prior abundance and estimates based on historical records. We analyzed genetic (mitochondrial control region) and isotopic information from modern and prehistoric gray whales using serial coalescent simulations and Bayesian skyline analyses to test for a pre-whaling decline and to examine prehistoric genetic diversity, population dynamics and ecology. Simulations demonstrate that significant genetic differences observed between ancient and modern samples could be caused by a large, recent population bottleneck, roughly concurrent with commercial whaling. Stable isotopes show minimal differences between modern and ancient gray whale foraging ecology. Using rejection-based Approximate Bayesian Computation, we estimate the size of the population bottleneck at its minimum abundance and the pre-bottleneck abundance. Our results agree with previous genetic studies suggesting the historical size of the eastern gray whale population was roughly three to five times its current size. PMID:22590499

Alter, S. Elizabeth; Newsome, Seth D.; Palumbi, Stephen R.

2012-01-01

348

Pre-whaling genetic diversity and population ecology in eastern Pacific gray whales: insights from ancient DNA and stable isotopes.  

PubMed

Commercial whaling decimated many whale populations, including the eastern Pacific gray whale, but little is known about how population dynamics or ecology differed prior to these removals. Of particular interest is the possibility of a large population decline prior to whaling, as such a decline could explain the ~5-fold difference between genetic estimates of prior abundance and estimates based on historical records. We analyzed genetic (mitochondrial control region) and isotopic information from modern and prehistoric gray whales using serial coalescent simulations and Bayesian skyline analyses to test for a pre-whaling decline and to examine prehistoric genetic diversity, population dynamics and ecology. Simulations demonstrate that significant genetic differences observed between ancient and modern samples could be caused by a large, recent population bottleneck, roughly concurrent with commercial whaling. Stable isotopes show minimal differences between modern and ancient gray whale foraging ecology. Using rejection-based Approximate Bayesian Computation, we estimate the size of the population bottleneck at its minimum abundance and the pre-bottleneck abundance. Our results agree with previous genetic studies suggesting the historical size of the eastern gray whale population was roughly three to five times its current size. PMID:22590499

Alter, S Elizabeth; Newsome, Seth D; Palumbi, Stephen R

2012-01-01

349

Characterizing Atmospheric Teleconnections in the Pliocene Epoch Using Stable Isotopes  

NASA Astrophysics Data System (ADS)

As atmospheric concentrations of CO2 continue to increase due to human activities, it becomes increasingly vital to understand how the hydrologic cycle has responded to warmer global temperatures in the past. The Pliocene climate offers an ideal window into a climate system in equilibrium with current atmospheric pCO2. During the Pliocene, the Southern United States was wetter than modern, an observation in contrast to our current understanding of future warming scenarios, which involve the expansion and poleward migration of the subtropical dry zone. Two distinct hypotheses exist to explain these anomalously wet conditions. The first is that they were a product of Pliocene boundary conditions including lower topography in the Western US. The second is that these conditions were caused by a south-shifted subtropical jet due to a weak zonal temperature gradient in the tropical Pacific, a state characteristic of modern El Nio years. To resolve this question, we seek to characterize atmospheric circulation over the Western US through the Plio-Pleistocene. In order to do this, we analyzed regional isotopic shifts from 4.0 - 1.0 Ma at 5 localities across the Western US measured in pedogenic carbonates. In addition, we compare these isotope profiles to modern observations of seasonal isotopic shifts in precipitation between phases of the El Nio Southern Oscillation (ENSO) at 77 stations across the country measured as part of the United States Network of Isotopes in Precipitation (USNIP). We find that when accounting for seasonality of carbonate precipitation, isotopic shifts across the late Pliocene in all but one locality match modern shifts between El Nio and Neutral phases of ENSO. In addition, isotopic shifts at all localities spanning 4.0 - 1.0 Ma change direction at the Plio-Pleistocene boundary to return to mid-Pliocene values by the mid-Pleistocene. Pleistocene atmospheric circulation is much better constrained over the Western US and, similar to El Nio circulation, involves a deeper Aleutian low and south-shifted subtropical jet. These two independent results support the idea that wet conditions in the Pliocene Southern US can be attributed to a south-shifted subtropical jet controlled by the temperature structure of the Equatorial Pacific. This also suggests that teleconnections between the tropics and mid-latitudes were similar to modern despite a weaker meridional temperature gradient.

Winnick, M. J.; Welker, J. M.; Chamberlain, C. P.

2011-12-01

350

Stable Nitrogen and Carbon Isotope Ratios Indicate Traditional and Market Food Intake in an Indigenous Circumpolar Population123  

PubMed Central

The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yupik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (?15N and ?13C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. First, we analyzed the ?15N and ?13C values of a comprehensive sample of Yupik foods. We found that ?15N values were elevated in fish and marine mammals and that ?13C values were elevated in market foods containing corn or sugar cane carbon. Second, we evaluated the associations between RBC ?15N and ?13C values and self-reported measures of traditional and market food intake (n = 230). RBC ?15N values were correlated with intake of fish and marine mammals (r = 0.52; P < 0.0001). RBC ?13C values were correlated with intake of market foods made from corn and sugar cane (r = 0.46; P < 0.0001) and total market food intake (r = 0.46; P < 0.0001). Finally, we assessed whether stable isotope ratios captured population-level patterns of traditional and market intake (n = 1003). Isotopic biomarkers of traditional and market intake were associated with age, community location, sex, and cultural identity. Self-report methods showed variations by age and cultural identity only. Thus, stable isotopes show potential as biomarkers for monitoring dietary change in indigenous circumpolar populations. PMID:22157543

Nash, Sarah H.; Bersamin, Andrea; Kristal, Alan R.; Hopkins, Scarlett E.; Church, Rebecca S.; Pasker, Renee L.; Luick, Bret R.; Mohatt, Gerald V.; Boyer, Bert B.; O'Brien, Diane M.

2012-01-01

351

Seasonal reliance on nectar by an insectivorous bat revealed by stable isotopes.  

PubMed

Many animals have seasonally plastic diets to take advantage of seasonally abundant plant resources, such as fruit or nectar. Switches from insectivorous diets that are protein rich to fruits or nectar that are carbohydrate rich present physiological challenges, but are routinely done by insectivorous songbirds during migration. In contrast, insectivorous bat species are not known to switch diets to consume fruit or nectar. Here, we use carbon stable isotope ratios to establish the first known case of a temperate bat species consuming substantial quantities of nectar during spring. We show that pallid bats (Antrozous pallidus) switch from a diet indistinguishable from that of sympatric insectivorous bat species in winter (when no cactus nectar is present) to a diet intermediate between those of insectivorous bats and nectarivorous bats during the spring bloom of a bat-adapted cactus species. Combined with previous results that established that pallid bats are effective pollinators of the cardon cactus (Pachycereus pringlei), our results suggest that the interaction between pallid bats and cardon cacti represents the first-known plant-pollinator mutualism between a plant and a temperate bat. Diet plasticity in pallid bats raises questions about the degree of physiological adaptations of insectivorous bats for incorporation of carbohydrate-rich foods, such as nectar or fruit, into the diet. PMID:24276770

Frick, Winifred F; Shipley, J Ryan; Kelly, Jeffrey F; Heady, Paul A; Kay, Kathleen M

2014-01-01

352

High-Sensitivity Stable-Isotope Probing by a Quantitative Terminal Restriction Fragment Length Polymorphism Protocol  

PubMed Central

Stable-isotope probing (SIP) has proved a valuable cultivation-independent tool for linking specific microbial populations to selected functions in various natural and engineered systems. However, application of SIP to microbial populations with relatively minor buoyant density increases, such as populations that utilize compounds as a nitrogen source, results in reduced resolution of labeled populations. We therefore developed a tandem quantitative PCR (qPCR)TRFLP (terminal restriction fragment length polymorphism) protocol that improves resolution of detection by quantifying specific taxonomic groups in gradient fractions. This method combines well-controlled amplification with TRFLP analysis to quantify relative taxon abundance in amplicon pools of FAM-labeled PCR products, using the intercalating dye EvaGreen to monitor amplification. Method accuracy was evaluated using mixtures of cloned 16S rRNA genes, DNA extracted from low- and high-G+C bacterial isolates (Escherichia coli, Rhodococcus, Variovorax, and Microbacterium), and DNA from soil microcosms amended with known amounts of genomic DNA from bacterial isolates. Improved resolution of minor shifts in buoyant density relative to TRFLP analysis alone was confirmed using well-controlled SIP analyses. PMID:22038597

Andeer, Peter; Stahl, David A.

2012-01-01

353

Using stable isotopes to differentiate trophic feeding channels within soil food webs.  

PubMed

The soil is probably the most diverse habitat there is, with organisms ranging in sizes from less than 1?m to several metres in length. However, it is increasingly evident that we know little about the interactions occurring between these organisms, the functions that they perform as individual species, or together within their different feeding guilds. These interactions between groups of organisms and physical and chemical processes shape the soil as a habitat and influence the nature of the soil food web with consequences for the above-ground vegetation and food web. Protists are known as one of the most abundant groups of bacterivores within the soil; however, they are also consumers of a number of other food sources. Even though they are responsible for a large proportion of the mineralisation of bacterial biomass and have a large impact on the C and N cycles within the soil they are regularly overlooked when investigating the complete soil food web. Recently, stable isotopes have been used to determine trophic interactions and here we describe how this technique has been used to highlight linkages between protists and the soil food web. PMID:22299758

Crotty, Felicity V; Adl, Sina M; Blackshaw, Rod P; Murray, Philip J

2012-01-01

354

STABLE ISOTOPES ISSUE Alessandra Fravolini Kevin R. Hultine  

E-print Network

contrasting soil textures (sandy-loam vs. loamy-clay) in semi-desert grassland in southeastern Arizona, USAD), the abundance of 13 C in soluble leaf sugar (d13 C), and percent volumetric soil water content (hv) were, the fraction of pulse water in stem xylem decreased more rapidly on the loamy-clay soil than the sandy

Williams, David G.

355

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

PubMed

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

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

2010-01-01

356

Estimation of soil water evaporative loss after tillage operation using the stable isotope technique  

NASA Astrophysics Data System (ADS)

Application of stable isotopes in soil studies has improved quantitative evaluation of evaporation and other hydrological processes in soil. This study was carried out to determine the effect of tillage on evaporative loss of water from the soil. Zero tillage and conventional tillage were compared. Suction tubes were installed for soil water collection at the depths 0.15, 0.50, and 1.0 m by pumping soil water with a peristaltic pump. Soil water evaporation was estimated using stable isotopes of water. The mean isotopic composition of the soil water at 0.15 m soil depth were -1.15 (?18O) and -0.75 (?D) and were highly enriched compared with the isotopic compositions of the site precipitation. Soil water stable isotopes (?18O and ?D) were more enriched near the surface under zero tillage while they were less negative down the profile under zero tillage. This suggests an occurrence of more evaporation and infiltration under conventional then zero tillage, respectively, because evaporative fractionation contributes to escape of lighter isotopes from liquid into the vapour phase leading to enrichment in heavy isotopes in the liquid phase. The annual evaporation estimated using the vapour diffusion equation ranges from 46-70 and 54-84 mm year-1 under zero and conventional tillage, respectively, indicating more evaporation under conventional tillage compared with zero tillage. Therefore, to reduce soil water loss, adoption of conservation tillage practices such as zero tillage is encouraged.

Busari, M. A.; Salako, F. K.; Tuniz, C.; Zuppi, G. M.; Stenni, B.; Adetunji, M. T.; Arowolo, T. A.

2013-09-01

357

Neutrino scattering off the stable even-even Mo isotopes  

SciTech Connect

Inelastic neutrino-nucleus reaction cross sections are studied focusing on the neutral current processes. Particularly, we investigate the angular and initial neutrino-energy dependence of the differential and integrated cross sections for low and intermediate energies of the incoming neutrino. The nuclear wave functions for the initial and final nuclear states are constructed in the context of the quasi-particle random phase approximation (QRPA) tested on the reproducibility of the low-lying energy spectrum. The results presented here refer to the isotopes Mo{sup 92}, Mo{sup 94}, Mo{sup 96}, Mo{sup 98} and Mo{sup 100}. These isotopes could play a significant role in supernova neutrino detection in addition to their use in double-beta and neutrinoless double-beta decay experiments (e.g. MOON, NEMO III)

Balasi, K. G.; Kosmas, T. S.; Divari, P. C. [Theoretical Physics Section, University of Ioannina, GR 45110 Ioannina (Greece)

2009-11-09

358

Using Stable Isotopes to Trace Microbial Hydrogen Production Pathways  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

359

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

NASA Astrophysics Data System (ADS)

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 (TMOP-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.

Horvth, Anik; Fut, Istvn; Palcsu, Lszl

2014-05-01

360

Determination of stable carbon and hydrogen isotopes of light hydrocarbons  

Microsoft Academic Search

A combined system for the measurement of ¹³C\\/¹²C and D\\/H ratios on light hydrocarbons (C-C) and CO is described. The system is designed for natural gas and sediment gas analyses. It comprises gas chromatographic separation with online combustion of hydrocarbons to CO and HO, reduction of HO to H on zinc in closed ampules, and mass spectrometric determination of isotope

Ingolf. Dumke; Eckhard. Faber; Juergen. Poggenburg

1989-01-01

361

Carbon cycle for Lake Washington - a stable isotope study  

Microsoft Academic Search

The authors investigate the carbon cycle in Lake Washington for the year 1980 using monthly measurements of the dissolved inorganic carbon (DIC) and its ¹³C:¹²C isotopic composition. Mass balances of DIC and its ¹³C:¹²C yield estimates of CO gas exchange rates and net organic carbon production rates. Between 24 June and 13 August, the calculated CO gas invasion rate of

P. D. Quay; S. R. Emerson; B. M. Quay; A. H. Devol

1986-01-01

362

Stable carbon isotopes: Possible clues to early life on mars  

Microsoft Academic Search

Organic and inorganic carbon in terrestrial near-surface environments are characterized by a marked difference in their 13C\\/12C ratios which can be traced back in the Earth's sedimentary record over almost 4 billion years. There is no doublt that the bias in favour of 12C displayed by biogenic matter derives, for the most part, from the isotope-selecting properties of the carbon-fixing

Manfred Schidlowski

1992-01-01

363

Stable carbon and nitrogen isotope enrichment in primate tissues  

PubMed Central

Isotopic studies of wild primates have used a wide range of tissues to infer diet and model the foraging ecologies of extinct species. The use of mismatched tissues for such comparisons can be problematic because differences in amino acid compositions can lead to small isotopic differences between tissues. Additionally, physiological and dietary differences among primate species could lead to variable offsets between apatite carbonate and collagen. To improve our understanding of the isotopic chemistry of primates, we explored the apparent enrichment (?*) between bone collagen and muscle, collagen and fur or hair keratin, muscle and keratin, and collagen and bone carbonate across the primate order. We found that the mean ?* values of proteinaceous tissues were small (?1), and uncorrelated with body size or phylogenetic relatedness. Additionally, ?* values did not vary by habitat, sex, age, or manner of death. The mean ?* value between bone carbonate and collagen (5.61.2) was consistent with values reported for omnivorous mammals consuming monoisotopic diets. These primate-specific apparent enrichment values will be a valuable tool for cross-species comparisons. Additionally, they will facilitate dietary comparisons between living and fossil primates. Electronic supplementary material The online version of this article (doi:10.1007/s00442-010-1701-6) contains supplementary material, which is available to authorized users. PMID:20628886

Carter, Melinda L.; Karpanty, Sarah M.; Zihlman, Adrienne L.; Koch, Paul L.; Dominy, Nathaniel J.

2010-01-01

364

Low stable carbon isotope fractionation by coccolithophore RubisCO  

NASA Astrophysics Data System (ADS)

The 13C/ 12C ratio of carbon compounds is used to identify sources and sinks in the global carbon cycle. However, the relatively enriched 13C content observed for marine organic carbon remains enigmatic. The majority of oceanic carbon is fixed by algae and cyanobacteria via the Calvin-Benson-Bassham cycle, yet isotopic discrimination by the CO 2 fixation enzyme, RubisCO (ribulose 1,5-bisphosphate carboxylase/oxygenase), has only been measured for a single marine cyanobacterium. Different forms of RubisCO occur in different phytoplankton species (overall amino acid identity varying by as much as 75%) and thus may vary in the degree to which they fractionate carbon. Here we measured isotope discrimination by RubisCO from the coccolithophore Emiliania huxleyi, a cosmopolitan species used as a marine algal model .E. huxleyi RubisCO discriminated substantially less ( ? = 11.1) against 13CO 2 than other RubisCO enzymes (18-29), despite having Michaelis-Menten kinetic parameters ( K = 72 ?M; Vmax = 0.66 ?mol min -1 mg -1 protein) similar to those measured for RubisCO enzymes from different organisms. If widespread, decreased isotope discrimination of 13C by phytoplankton RubisCO may be a major factor influencing the enriched 13C content of marine organic carbon. This finding emphasizes the necessity of (a) determining ? values for RubisCOs of other marine phytoplankton and (b) re-evaluation of ?13C values from physiological, environmental, and geological studies.

Boller, Amanda J.; Thomas, Phaedra J.; Cavanaugh, Colleen M.; Scott, Kathleen M.

2011-11-01

365

Stable carbon and nitrogen isotope enrichment in primate tissues.  

PubMed

Isotopic studies of wild primates have used a wide range of tissues to infer diet and model the foraging ecologies of extinct species. The use of mismatched tissues for such comparisons can be problematic because differences in amino acid compositions can lead to small isotopic differences between tissues. Additionally, physiological and dietary differences among primate species could lead to variable offsets between apatite carbonate and collagen. To improve our understanding of the isotopic chemistry of primates, we explored the apparent enrichment (?*) between bone collagen and muscle, collagen and fur or hair keratin, muscle and keratin, and collagen and bone carbonate across the primate order. We found that the mean ?* values of proteinaceous tissues were small (?1), and uncorrelated with body size or phylogenetic relatedness. Additionally, ?* values did not vary by habitat, sex, age, or manner of death. The mean ?* value between bone carbonate and collagen (5.61.2) was consistent with values reported for omnivorous mammals consuming monoisotopic diets. These primate-specific apparent enrichment values will be a valuable tool for cross-species comparisons. Additionally, they will facilitate dietary comparisons between living and fossil primates. PMID:20628886

Crowley, Brooke E; Carter, Melinda L; Karpanty, Sarah M; Zihlman, Adrienne L; Koch, Paul L; Dominy, Nathaniel J

2010-11-01

366

Preliminary mineralogic, fluid inclusion, and stable isotope study of the Mahd adh Dhahab gold mine, Kingdom of Saudi Arabia  

USGS Publications Warehouse

The Mahd adh Dhahab mine, located about 280 km northeast of Jiddah, Kingdom of Saudi Arabia, has yielded more than 2 million ounces of gold from periodic production during the past 3,000 years. A new orebody on the southern side of the ancient workings, known as the South orebody, is being developed by Gold Fields-Mahd adh Dhahab Limited. A suite of samples was collected from the newly exposed orebody for preliminary mineralogic, stable isotope, fluid inclusion, and geochemical studies. The Mahd adh Dhahab deposit is in the carapace of a Proterozoic epizonal rhyolite stock that domed pyroclastic and metasedimentary rocks of the Proterozoic Halaban group. Ore of gold, silver, copper, zinc, tellurium, and lead is associated with north-trending, steeply dipping quartz veins in a zone 1,000 m long and 400 m wide. The veins include an assemblage of quartz-chlorite-pyrite-hematite-chalcopyrite-sphalerite-precious metals, which is similar to the mineral assemblage at the epithermal deposit at Creede, Colorado. The primary ore contains abundant chalcopyrite, sphalerite, and pyrite in addition to a complex precious metal assemblage. Gold and silver occur principally as minute grains of telluride minerals disseminated in quartz-chlorite-hematite and as inclusions in chalcopyrite and sphalerite. Telluride minerals include petzite, hessite, and sylvanite. Free gold is present but not abundant. All of the vein-quartz samples contained abundant, minute inclusions of both low-density, vapor-rich fluids and liquid-rich fluids. Primary fluid inclusions yielded homogenization temperatures of from 110? to 238? C. Preliminary light-stable isotope studies of the sulfide minerals and quartz showed that all of the d34S values are between 1.2 and 6.3 per mil, which is a typical range for hydrothermal sulfide minerals that derive their sulfur from an igneous source. The data-suggest that the sulfide sulfur isotope geochemistry was controlled by exchange with la large sulfur isotope reservoir at depth. The d18O values of all stages of vein quartz in the South orebody range between 8.5 and 11.1 per mil. This range is similar to that for quartz from the North orebody and indicates that the hydrothermal system consisted of dominantly exchanged meteoric water, which was uniform in temperature and d18O content throughout the area during the entire period of mineralization. Lead isotope analyses of two galena samples indicate that the lead in the South orebody is less radiogenic than that from the North orebody and confirm that the lead was derived from oceanic crust approximately 700 Ma ago.

Rye, Robert O.; Hall, W.E.; Cunningham, C.G.; Czamanske, G.K.; Afifi, A.M.; Stacey, J.S.

1983-01-01

367

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

USGS Publications Warehouse

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.

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

2004-01-01

368

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

Microsoft Academic Search

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

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

369

Impact of diazotrophy on N stable isotope signatures of nitrate and particulate organic nitrogen: case studies in the north-eastern tropical Atlantic Ocean  

Microsoft Academic Search

During two independent cruises in the north-eastern tropical Atlantic Ocean, we applied two different approaches to investigate the impact of diazotrophy on nitrogen stable isotope signatures in nitrate and particulate organic nitrogen (PON) of the food-web constituents. The first approach, used during the Poseidon cruise 348 in the Mauritanian upwelling, investigated the long-term influence of diazotrophy on the natural abundance

Nicola Wannicke; Iris Liskow; Maren Voss

2010-01-01

370

Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry  

USGS Publications Warehouse

An anomalous stable hydrogen isotopic fractionation of 4 ??? in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ??2H reproducibility (1?? standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1 ??? to 0.58 ???. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen. ?? This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society.

Coplen, T.B.; Qi, H.

2010-01-01

371

Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry  

USGS Publications Warehouse

An anomalous stable hydrogen isotopic fractionation of 4 in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) ?2H reproducibility (1& sigma; standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1 to 0.58 . This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen

Coplen, Tyler B.; Qi, Haiping

2010-01-01

372

Stable isotope determination of ester and ether methyl moieties in plant methoxyl groups.  

PubMed

Plant methoxyl groups of lignin and pectin have both distinct stable hydrogen isotope (?(2)H) and carbon isotope (?(13)C) values that can be used for studying environmental processes and for investigating the origin and authenticity of biomaterials. Up to now, the reported methods have been applied only to determine isotope values of the bulk plant methoxyl pool. In this work, we have applied several methods to distinguish between stable isotope ratios of methoxyl groups of pectin and the bulk plant methoxyl pool. Our results demonstrate that by applying alkaline hydrolysis to specifically cleave off the ester methyl moiety (pectin-like), we can distinguish ?(2)H and ?(13)C values of the pectin methoxyl pool from the bulk methoxyl pool. No measureable isotope discrimination was observed either during sample preparation or during analytical measurement. Furthermore, using this method, no major isotope difference in either the hydrogen or carbon isotope signature of the methoxyl groups of plant pectin and bulk matter from plant species such as leaves from trees, apples, carrots and potatoes was noted. We show the methanol released during alkaline hydrolysis of plant material and subsequently treated with hydriodic acid to be an excellent procedure to measure specifically and precisely the ?(13)C and ?(2)H isotope values of plant pectin-like methoxyl groups. This method is particularly advantageous when plant matter with a low methoxyl content has to be analysed. PMID:22004278

Greule, Markus; Keppler, Frank

2011-12-01

373

Stable Isotopes James R Ehleringer and Thure E Cerling  

E-print Network

for introduction into the mass spectrometer. The most commonly used approaches involve introducing hydrogen as H2 rationing mass spectrometer. The mass spectrometer consists of a source to ionize the gas, a flight tube which are stable and that do not decay through radioactive pro- cesses over time. Most elements consist

Ehleringer, Jim

374

Identification of Methane, Ethane, and Propane Oxidizing Bacteria at Marine Hydrocarbon Seeps by Stable Isotope Probing  

NASA Astrophysics Data System (ADS)

Hydrocarbon seeps emit substantial amounts of oil and natural gas into the marine environment, where they can be oxidized by microorganisms in the sediment and water column. Here, we used stable isotope probing of DNA and lipid biomarkers to identify the microorganisms actively consuming 13C-labeled natural gas compounds in seep sediment samples. Surface sediment was collected from the Coal Oil Point seep field (offshore Santa Barbara, California, USA) and incubated under aerobic conditions with 13C labeled methane, ethane, or propane for up to 37 days, with sediment sub-samples taken at 3-4 intermediate time points. DNA was extracted from sediment and separated by CsCl density gradient centrifugation. The microbial community in each fraction was profiled using T-RFLP, and bacterial 16S rRNA gene clone libraries were constructed from un-incubated hydrocarbon seep sediment and selected isotopically 'heavy' (13C) and 'light' (12C) gradient fractions from ethane incubations. All clone libraries were dominated by sequences from members of the family Rhodobacteraceae (>25% of sequences) and a diverse group of Gammaproteobacteria, including sequences related to those of methylotrophs and to those of bacteria known to consume the longer-chain alkanes present in crude oil. After 14 days of incubation, the relative abundance of Rhodobacteraceae was higher in 'heavy' fractions from the 13C-ethane incubation than in 'light' fractions, suggesting incorporation of 13C label. The Rhodobacteraceae are very diverse metabolically, but have often been observed in abundance in oil contaminated seawater. Several members of this group have been shown to oxidize longer chain alkanes (C10 or higher), but none have been previously linked to the consumption of the gaseous alkanes ethane, propane, and butane. For the final time point, 13C content of phospholipid fatty acids (PLFA) were also analyzed, showing substantial incorporation of 13C over 37 days. In the methane incubation, approximately 75% of the 13C incorporated into PLFA was found in fatty acids 18:1(6), 16:0, 18:1(8), and 16:1(6), suggesting that both type I and type II methanotrophs were involved in methane oxidation. In the case of ethane, 18:1(6), 18:1(8), and 16:1(6) were also highly labeled (>10% 13C), but composed a much lower fraction of total PFLA than in the methane incubation. Instead, fatty acids anteiso-15:0 and 14:0 accounted for approximately 50% of 13C-ethane incorporated into PLFA, indicating that a different group of organisms was responsible for the bulk of ethane consumption. Additional results from the methane and propane incubations will also be presented.

Redmond, M.; Ding, H.; Friedrich, M. W.; Valentine, D. L.

2008-12-01

375

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

NASA Astrophysics Data System (ADS)

The pelagic food web of the Scotia Sea was studied by analysing natural abundances of nitrogen and carbon stable isotopes of primary producers and pelagic consumers, sampled from the seasonal ice edge in the south to the Antarctic Polar Front in the north. The analysis covered, within a single mid-summer period, particulate organic matter (POM) and 38 taxa, ranging from suspension feeding copepods and salps to omnivorous euphausiids, pelagic fish and higher, land-based predators including fur seals, penguins and flying birds. Spatial variation in ? 15N of POM correlated well with nutrient availability and primary productivity. Latitudinal differences in ? 13C of POM were closely linked to variations in temperature, nutrients and productivity depending on the frontal region sampled. This translated to equivalent (although smaller) regional ? 13C differences among higher trophic levels. The trophic positions of species based on isotope values broadly agreed with previously published dietary data with three important exceptions. First, the carnivorous amphipod Themisto gaudichaudii had anomalously low ? 15N values. Second, Euphausia superba had ? 15N values that were also surprisingly low, considering the abundant literature suggesting its omnivory. Third, the copepod Rhincalanus gigas, considered a suspension feeder, had unexpectedly high ? 15N values rather more in keeping with omnivorous feeding. The consumer ? 15N values ranged from 1.2 (min.) measured in Salpa thompsoni (designated here as trophic level (TL) 2 across all regions) to 15.2 (max.) measured in white-chinned petrels ( Procellaria aequinoctialis, calculated as TL5 relative to the TL2 of salps). Excluding seabirds, the resulting food chain length of 3.7 TL (above POM at TL1) was lower than in most other Southern Ocean and temperate marine pelagic ecosystems. The majority (60%) of vertebrate predators occupied only 1-1.5 trophic levels above the herbivorous suspension feeders such as krill. This indicates the existence of the classic short food chain of POM-suspension feeder-vertebrate predator. However the presence of trophic levels 4 and above indicates the existence of alternative trophic pathways, for example involving myctophid fish or carrion, and that some wide-ranging predators which breed at South Georgia also feed outside the region. This conclusion is supported first by the continuum of ? 15N values between krill, suspension feeding copepods and myctophid fish, and secondly by higher trophic levels in several of the myctophid species in the low-krill region of the northern Scotia Sea, suggesting latitudinal differences in food web structure and food chain length.

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

2012-01-01

376

Environmental Reconstruction of the Arctic middle Eocene using Stable Isotope Analyses of Terrestrial Substrates  

NASA Astrophysics Data System (ADS)

I report on reconstructions of key environmental attributes of the Arctic middle Eocene (circa 45 Ma) using stable isotope analyses of terrestrial substrates from Axel Heiberg Island. The field site, now located in the far north of Canada, was home to extensive forests of deciduous conifers living at approximately 83 degrees North latitude during the middle Eocene. Fossils of these trees and associated soils are known for their spectacular preservation. Here I describe my vision of the middle Eocene Arctic environment, including the lack of polar ice, the high relative humidity, high levels of soil methane production, site temperature, and patterns of seasonality. These estimates were generated from stable isotope studies of oxygen and hydrogen in fossil cellulose, carbon and oxygen in paleosol carbonate and hydrogen within lipid biomarkers. I also report on our recent advances in the understanding of the oxygen isotopic exchange specific to position within the cellulose molecule, and its implications for the interpretation of isotopic analyses of cellulose.

Jahren, A.

2006-05-01

377

Stable isotope-labeling studies in metabolomics: new insights into structure and dynamics of metabolic networks  

PubMed Central

The rapid emergence of metabolomics has enabled system-wide measurements of metabolites in various organisms. However, advances in the mechanistic understanding of metabolic networks remain limited, as most metabolomics studies cannot routinely provide accurate metabolite identification, absolute quantification and flux measurement. Stable isotope labeling offers opportunities to overcome these limitations. Here we describe some current approaches to stable isotope-labeled metabolomics and provide examples of the significant impact that these studies have had on our understanding of cellular metabolism. Furthermore, we discuss recently developed software solutions for the analysis of stable isotope-labeled metabolomics data and propose the bioinformatics solutions that will pave the way for the broader application and optimal interpretation of system-scale labeling studies in metabolomics. PMID:24568354

Chokkathukalam, Achuthanunni; Kim, Dong-Hyun; Barrett, Michael P; Breitling, Rainer; Creek, Darren J

2014-01-01

378

Stable isotope fractionation during ultraviolet photolysis of N2O  

NASA Astrophysics Data System (ADS)

The biogeochemical cycling of nitrous oxide plays an important role in greenhouse forcing and ozone regulation. Laboratory studies of N2O:N2 mixtures irradiated between 193-207 nm reveal a significant enrichment of the residual heavy nitrous oxide isotopomers. The isotopic signatures resulting from photolysis are well modeled by an irreversible Rayleigh distillation process, with large enrichment factors of ?15,18(193 nm) = -18.4,-14.5 per mil and ?15,18(207 nm) = -48.7,-46.0 per mil. These results, when combined with diffusive mixing processes, have the potential to explain the stratospheric enrichments previously observed.

Rahn, Thom; Zhang, Hui; Wahlen, Martin; Blake, Geoffrey A.

379

Stable isotope fractionation during ultraviolet photolysis of N2O  

Microsoft Academic Search

The biogeochemical cycling of nitrous oxide plays an important role in greenhouse forcing and ozone regulation. Laboratory studies of N2O:N2 mixtures irradiated between 193-207 nm reveal a significant enrichment of the residual heavy nitrous oxide isotopomers. The isotopic signatures resulting from photolysis are well modeled by an irreversible Rayleigh distillation process, with large enrichment factors of ?15.18(193nm)=-18.4,-14.5permil and ?15.18(207nm)=-48.7,-46.0permil. These

Thom Rahn; Hui Zhang; Martin Wahlen; Geoffrey A. Blake

1998-01-01

380

Coral mucus stable isotope composition and labeling: experimental evidence for mucus uptake by epizoic acoelomorph worms  

Microsoft Academic Search

Mucus released by scleractinian corals can act as an important energy and nutrient carrier in coral reef ecosystems, and a\\u000a distinct isotopic signature would allow following the fate of this material. This study investigates the natural C and N stable\\u000a isotopic signatures of mucus released by four scleractinian coral genera (Acropora, Fungia, Pocillopora and Stylophora) in comparison with those of

Malik S. Naumann; Christoph Mayr; Ulrich Struck; Christian Wild

2010-01-01

381

TESTING ISOSOURCE: STABLE ISOTOPE ANALYSIS OF A TROPICAL FISHERY WITH DIVERSE ORGANIC MATTER SOURCES  

Microsoft Academic Search

We sampled consumers and organic matter sources (mangrove litter, fresh- water swamp-forest litter, seagrasses, seagrass epiphytes, and marine particulate organic matter (MPOM)) from four estuaries on Kosrae, Federated States of Micronesia for stable isotope (d13C and d34S) analysis. Unique mixing solutions cannot be calculated in a dual- isotope, five-endmember scenario, so we tested IsoSource, a recently developed statistical procedure that

Jonathan P. Benstead; James G. March; Brian Fry; Katherine C. Ewel; Catherine M. Pringle

2006-01-01

382

Microsampling of Fish Otoliths: A Comparison Between DM 2800 and Dremel in Stable Isotope Analysis  

Microsoft Academic Search

This paper describes and compares two microsampling methods, DM 2800 and Dremel, which were used in taking aragonite samples from otolith zones of cod, Gadus morhua, for stable isotope analysis. There were no significant differences between the two sampling methods both in carbon and oxygen isotope ratios (13C\\/12C, 18O\\/16O) and in annual and seasonal otolith zones. The possible finite effect

Yongwen Gao

1999-01-01

383

Using stable isotopes to assess seasonal patterns of avian predation across a terrestrial-marine landscape  

Microsoft Academic Search

In this study, we used the stable isotope ratios 15N\\/14N and 13C\\/12C to clarify the spatial and temporal patterns of small mammal derpredation by wide-ranging raptors across a salt marsh and grassland landscape. To determine whether clear isotope signals existed for the two adjoining habitats, and if these differences could allow for an assessment of the seasonal habitat origins of

Elaine K. Harding; Emiko Stevens

2001-01-01

384

Resource-Consumer Relationships and Baseline Stable Isotopic Signatures of Food Webs in Isolated Wetlands  

Microsoft Academic Search

We examined isolated wetland food webs using stable C and N isotopes to understand resource-consumer relationships and controls\\u000a on baseline isotopic signatures. Marshes were usually more 13C-enriched than cypress savannas and cypress gum swamps. Analysis of coarse particulate organic matter (CPOM) fractions indicated\\u000a that C3 plants contributed the majority of organic matter to isolated wetlands. Individual wetlands of the same

Stephen P. Opsahl; Stephen W. Golladay; Lora L. Smith; Stephanie E. Allums

2010-01-01

385

Activation techniques for the determination of stable isotopes of cerium in blood plasma  

Microsoft Academic Search

Information on the biokinetics of cerium can be obtained directly from humans by using stable isotopes as tracers. Neutron,\\u000a photon and proton activation analysis have all been tested as analytical techniques able to quantify different isotopes of\\u000a the same element in biological fluids. The experimental conditions were optimized for Ce analysis in blood plasma samples.\\u000a The performances of the different

M. C. Cantone; A. Giussani; I. Veronese; B. Candoni; Yu. M. Tsipenyuk; V. I. Firsov; A. L. Kersin

2007-01-01

386

Using ? 13 C stable isotopes to quantify individual-level diet variation  

Microsoft Academic Search

Individual-level diet variation can be easily quantified by gut-content analysis. However, because gut contents are a snapshot\\u000a of individuals feeding habits, such cross-sectional data can be subject to sampling error and lead one to overestimate levels\\u000a of diet variation. In contrast, stable isotopes reflect an individuals long-term diet, so isotope variation among individuals\\u000a can be interpreted as diet variation. Nevertheless,

Mrcio S. Arajo; Daniel I. Bolnick; Glauco Machado; Ariovaldo A. Giaretta; Srgio F. dos Reis

2007-01-01

387

A first look at the distribution of the stable isotopes of silicon in natural waters  

Microsoft Academic Search

The first data on the distribution of the stable isotopes of silicon in marine and freshwater systems are reported. Both marine and riverine ?30Si are more positive than ?30Si of igneous rocks, suggesting isotopic fractionation during weathering and clay formation and\\/or biomineralization. The ?30Si value for dissolved silicic acid from several ocean basins is +1.1 0.3 (n = 69).

Christina L. De La Rocha; Mark A. Brzezinski; Michael J. DeNiro

2000-01-01

388

Linking breeding and wintering grounds of neotropical migrant songbirds using stable hydrogen isotopic analysis of feathers  

Microsoft Academic Search

Recent studies have shown that stable hydrogen isotope ratios (?D) in the tissues of animals often correlate with ?D of local\\u000a precipitation. Here we examined the relationship between ?D in feathers and growing season precipitation for neotropical migrant\\u000a songbirds breeding over a continent-wide isotopic gradient. ?D values were determined on feathers of 140 individuals of 6\\u000a species of wild insectivorous

K. A. Hobson; Leonard I. Wassenaar

1996-01-01

389

Bromine and stable isotopic profiles of formation waters from potash mine-shafts, Saskatchewan, Canada  

Microsoft Academic Search

Sixty-five inflow samples from access shafts were collected at three separate potash mines in order to construct three 1000m deep hydrochemical profiles. Bromine concentrations, and ?D and ?18O stable isotopic compositions, increase with depth in each case. Measured isotopic ratios have not changed in 15+ years since the mine-inflows were first sampled, implying little change in the hydraulic regimes at

G. K. S. Jensen; B. J. Rostron; M. J. M. Duke; C. Holmden

2006-01-01

390

Stable carbon isotope ratios of fatty acids in seagrass and redhead ducks  

Microsoft Academic Search

Fatty acids were extracted from roots and rhizomes of the seagrass, Halodule wrightii, and from subcutaneous fat tissues of eight redhead ducks (Aythya americana) collected either in Texas or South Dakota. Stable carbon isotope ratios (?13C) of individual fatty acids were measured by gas chromatography\\/combustion\\/isotope ratio mass spectrometry (GC\\/C\\/IRMS). In cases where individual fatty acids were not completely resolved by

Beth Trust Hammer; Marilyn L. Fogel; Thomas C. Hoering

1998-01-01

391

Stable isotope composition of Chara rudis incrustation in Lake Jasne, Poland  

Microsoft Academic Search

Stable isotope composition (?13C and ?18O) was analysed in mineral incrustation of Chara rudis and surrounding waters. This macroalga forms dense and extensive charophyte meadows and may significantly contribute to the\\u000a calcium carbonate precipitation and deposition of marl lake sediments. The study aimed to find out if charophyte calcium carbonate\\u000a was precipitated in an isotopic equilibrium with lake water and

M. Pe?echaty; K. Apolinarska; A. Pukacz; J. Krupska; M. Siepak; P. Boszke; M. Sinkowski

2010-01-01

392

Stable-carbon isotope ratios as a measure of marine versus terrestrial protein in ancient diets  

SciTech Connect

The stable-carbon isotope ratios for the flesh of marine and terrestrial animals from Canada's Pacific coast differ by 7.9 +- 0.4 per mil, reflecting the approx. 7 per mil difference between oceanic and atmospheric carbon. This difference is passed on to human consumers. The carbon isotopic values (delta /sup 13/C) for human collagen thus yield direct information on the relative amounts of marine and terrestrial foods in prehistoric diets.

Chisholm, B.S. (Simon Fraser Univ., Burnaby, British Columbia); Nelson, D.E.; Schwarcz, H.P.

1982-06-04

393

Stable Isotope Measurements of Martian Atmospheric CO2 at the Phoenix Landing Site  

Microsoft Academic Search

Carbon dioxide is a primary component of the martian atmosphere and reacts readily with water and silicate rocks. Thus, the stable isotopic composition of CO2 can reveal much about the history of volatiles on the planet. The Mars Phoenix spacecraft measurements of carbon isotopes [referenced to the Vienna Pee Dee belemnite (VPDB)] [delta13CVPDB = -2.5 4.3 per mil (0\\/00)

Paul B. Niles; William V. Boynton; John H. Hoffman; Douglas W. Ming; Dave Hamara

2010-01-01

394

Organic Matter Stable Isotope (? 13 C, ? 15 N) Response to Historical Eutrophication of Lake Taihu, China  

Microsoft Academic Search

We explored the use of carbon and nitrogen isotope ratios (?13C, ?15N) in sediment organic matter as proxy indicators of historical changes in the trophic state of Lake Taihu, the third largest\\u000a freshwater lake in China. Stable isotope signatures in four sediment cores spanning the 20th century were compared with instrumental\\u000a records of lake-water trophic state. The comparative study shows

Jinglu Wu; Lin Lin; Michael K. Gagan; Gerhard H. Schleser; Sumin Wang

2006-01-01

395

Use of stable isotopes to assess king and Spanish mackerel groups  

E-print Network

locations and boundaries between the Gulf of Mexico and Atlantic stocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2 A) An example of depletion along the length of a dorsal fin spine from the tip to the base. B) enrichment from...) off south Texas and south Florida, and depleted in 1SC in Louisiana and north Texas. Furthermore, he found that among offshore resident species of penaeid shrimps and stomatopods, the nitrogen isotope Table 1. Stable isotope differences between...

Roelke, Lynn Ann

2012-06-07

396

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

PubMed

Procedures in our laboratory have always been directed towards complete understanding of all processes involved and corrections needed etc., instead of relying fully on laboratory reference materials. This rather principal strategy (or attitude) is probably not optimal in the economic sense, and is not necessarily more accurate either. Still, it has proven to be very rewarding in its capability to detect caveats that go undiscovered in the standard way of measurement, but that do influence the accuracy or reliability of the measurement procedure. An additional benefit of our laboratory procedures is that it makes us capable of assisting the International Atomic Energy Agency (IAEA) with primary questions like mutual scale assignments and comparison of isotope ratios of the same isotope in different matrices (like delta(18)O in water, carbonates and atmospheric CO(2)), establishment of the (17)O-(18)O relation, and the replenishment of the calibration standards. Finally, for manual preparation systems with a low sample throughput (and thus only few reference materials analysed) it may well be the only way to produce reliable results. PMID:20183228

Meijer, Harro A J

2009-06-01

397

Influence of regional precipitation patterns on stable isotopes in ice cores from the central Himalayas  

NASA Astrophysics Data System (ADS)

Several ice cores have been recovered from the Dasuopu (DSP) Glacier and the East Rongbuk (ER) Glacier in the central Himalayas since the 1990s. Although the distance between the DSP and the ER ice core drilling sites is only ~ 125 km, the stable isotopic record (?18O or ?D) of the DSP core is interpreted in previous studies as a temperature proxy, while the ER core is interpreted as a precipitation proxy. Thus, the climatological significance of the stable isotopic records of these Himalayan ice cores remains a subject of debate. Based on analysis of regional precipitation patterns over the region, we find that remarkable discrepancy in precipitation seasonality between the two sites may account for their disparate isotopic interpretations. At the ER core site, the Indian summer monsoon (ISM) precipitation is dominating due to topographic blocking of the moisture from westerlies by the high ridges of Mt. Qomolangma (Everest), which results in a negative correlation between the ER ?18O or ?D record and precipitation amount along the southern slope of the central Himalayas in response to the "amount effect". At the DSP core site, in comparison with the ISM precipitation, the wintertime precipitation associated with the westerlies is likely more important owing to its local favorable topographic conditions for interacting with the western disturbances. Therefore, the DSP stable isotopic record may be primarily controlled by the westerlies. Our results have important implications for interpreting the stable isotopic ice core records recovered from different climatological regimes of the Himalayas.

Pang, H.; Hou, S.; Kaspari, S.; Mayewski, P. A.

2014-02-01

398

Effect of accumulation rate on water stable isotopes of near-surface snow in inland Antarctica  

NASA Astrophysics Data System (ADS)

changes in water stable isotopes in polar firn were investigated at three sites characterized by different accumulation rates along the East Antarctic ice divide near Dome Fuji. Water stable isotopes, major ion concentrations, and tritium contents of three 2-4 m deep pits were measured at high resolution (2 cm). Temporally, the snow pits cover the past 50 years with snow accumulation rates in the range of 29-41 kg m-2 a-1 around Dome Fuji. Oxygen isotopic profiles in the three pits do not show annual fluctuations, but instead exhibit multiyear cycles. These multiyear cycles are lower in frequency at Dome Fuji as compared with the other two sites. Peaks of water stable isotopes in the multiyear cycles correspond to some ion concentration minima in the pits, although such relationships are not observed in coastal regions. We propose that the extremely low accumulation environment keeps the snow layer at the near surface, which result in postdepositional modifications of isotopic signals by processes such as ventilation and vapor condensation-sublimation. We estimate that oxygen isotopic ratios could be modified by >10 and that the original seasonal cycle could be completely overprinted under the accumulation conditions at Dome Fuji. Moreover, stake measurements at Dome Fuji suggest that the large variability in snow accumulation rate is the cause of the multiyear cycles.

Hoshina, Yu; Fujita, Koji; Nakazawa, Fumio; Iizuka, Yoshinori; Miyake, Takayuki; Hirabayashi, Motohiro; Kuramoto, Takayuki; Fujita, Shuji; Motoyama, Hideaki

2014-01-01

399

Stable isotope evolution and paleolimnology of ancient Lake Creede  

USGS Publications Warehouse

The lacustrine carbonate and travertine (tufa) deposits of ancient Lake Creede preserve a remarkable record of the isotopic evolution of the lake. That record indicates that the ?18O of the lake water, and by analogy its salinity, evolved through evaporation. Limited ans less reliable data on hydrous minerals and fluid inclusions in early diagenetic carbonates indicate that the ?D of the lake waters also evolved through evaporation. The isotope data place restrictions on models of the physical limnology of the lake and its evolution. The closed-basin Lake Creede formed shortly after collapse of the 26.9 Ma Creede caldera. Throughout most of its history it occupied the northern three quarters of the moat between the resurgent dome and wall of the caldera. The Creede Formation was deposited in the basin, dominantly as lacustrine sediments. Travertine mounds interfinger with Creede Formation sediments along the inner and outer margins of the lake basin. An estimated one-half of the original thickness of the Creede Formation has been lost mainly to erosion although scattered remnants of the upper portion remain on the caldera walls. Two diamond core holes (CCM-1 and CCM-2) sampled the uneroded portion of the Creede Formation as part of the U.S. Continental Drilling Program. Volcaniclastic material, including tuff units deposited directly into the lake and ash washed in from the watershed, compose the main lithologies of the Creede Formation. These volcaniclastic strata were produced by episodic ring-fracture volcanism. Lacustrine carbonates make up about 15% of the section sampled by drill core. They occur as 1 mm to 2 cm low-Mg calcite laminar alternating with siliciclastic laminar in scattered intervals throughout the preserved section. The carbonate laminar are accumulations of 5-20 ?m crystallites (microparites) and brine shrimmp fecal pellets (peloids) composed mainly of microparasite particles. Low-Mg calcite also occurs as an early diagenetic replacement of gypsum or ikaite (CaCO3 6H2O) crystals grown displacively in the muds and silts neat the water-sediment interface (rice grains). Other studies indicate that aragonite was the original CaCO3 precipitate forming the microsparite and pelodial laminae and that it converted to calcite suring burual diagenesis. Samples from CCM-2 and nearby outcrop do not appear to have undergone significant isotope exchange during recrystallization. Samples from CCM-1 and nearby outcrop, however, appear to have undergone extensive oxygen isotope exchange with meteoric water-dominated fluids possibly during a local 17.6 Ma hydrothermal event. The ?18-?13C data set produced by microsampling of individual carbonate lamellae and rice grains is exceptional in several aspects and provides important clues concerning the evolution of limnologic structure of the lake and its chemical and isotopic composition. Travertine and ikaite pseudomorphs in travertine deposits extendthe record an additional 330m above the collar of CCM-2. The ?18O values on the CCM-2 samples range from 10.4% to 37.3% and ?13C values range from -10.8% to 9.6%. The data fall into two distinct groups, a covariant group and an invariant group. The covariant group shows a strong negative covariance and a large range of ?18O and ?13C values. The negative covariance is opposite that normally reported for lacustrine carbonates. The large range of ?18O and ?13C values requires that the carbonates precipitated from waters have a large range of temperature and carbon and oxygen isotopic composition. The invariant group has a narrow range of large ?18O values (35% to 2%) and a wide range of ?13C values (-10.8% to 9.6%), indicating precipitation from waters with a narrow range of temperature and ?18O but a wide range of in ?13C of aqueous carbon. The ranges of isotope values for microsparite and peloid samples are virtually identical; two-thirds are in the covariant group. By contrast, the values for almost all rice grain samples are in the in

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

2000-01-01

400

Stable isotope analysis of precipitation samples obtained via crowdsourcing reveals the spatiotemporal evolution of Superstorm Sandy.  

PubMed

Extra-tropical cyclones, such as 2012 Superstorm Sandy, pose a significant climatic threat to the northeastern United Sates, yet prediction of hydrologic and thermodynamic processes within such systems is complicated by their interaction with mid-latitude water patterns as they move poleward. Fortunately, the evolution of these systems is also recorded in the stable isotope ratios of storm-associated precipitation and water vapor, and isotopic analysis provides constraints on difficult-to-observe cyclone dynamics. During Superstorm Sandy, a unique crowdsourced approach enabled 685 precipitation samples to be obtained for oxygen and hydrogen isotopic analysis, constituting the largest isotopic sampling of a synoptic-scale system to date. Isotopically, these waters span an enormous range of values (> 21 for ?(18)O, > 160 for ?(2)H) and exhibit strong spatiotemporal structure. Low isotope ratios occurred predominantly in the west and south quadrants of the storm, indicating robust isotopic distillation that tracked the intensity of the storm's warm core. Elevated values of deuterium-excess (> 25) were found primarily in the New England region after Sandy made landfall. Isotope mass balance calculations and Lagrangian back-trajectory analysis suggest that these samples reflect the moistening of dry continental air entrained from a mid-latitude trough. These results demonstrate the power of rapid-response isotope monitoring to elucidate the structure and dynamics of water cycling within synoptic-scale systems and improve our understanding of storm evolution, hydroclimatological impacts, and paleo-storm proxies. PMID:24618882

Good, Stephen P; Mallia, Derek V; Lin, John C; Bowen, Gabriel J

2014-01-01

401

Stable Isotope Analysis of Precipitation Samples Obtained via Crowdsourcing Reveals the Spatiotemporal Evolution of Superstorm Sandy  

PubMed Central

Extra-tropical cyclones, such as 2012 Superstorm Sandy, pose a significant climatic threat to the northeastern United Sates, yet prediction of hydrologic and thermodynamic processes within such systems is complicated by their interaction with mid-latitude water patterns as they move poleward. Fortunately, the evolution of these systems is also recorded in the stable isotope ratios of storm-associated precipitation and water vapor, and isotopic analysis provides constraints on difficult-to-observe cyclone dynamics. During Superstorm Sandy, a unique crowdsourced approach enabled 685 precipitation samples to be obtained for oxygen and hydrogen isotopic analysis, constituting the largest isotopic sampling of a synoptic-scale system to date. Isotopically, these waters span an enormous range of values (21 for O, 160 for H) and exhibit strong spatiotemporal structure. Low isotope ratios occurred predominantly in the west and south quadrants of the storm, indicating robust isotopic distillation that tracked the intensity of the storm's warm core. Elevated values of deuterium-excess (25) were found primarily in the New England region after Sandy made landfall. Isotope mass balance calculations and Lagrangian back-trajectory analysis suggest that these samples reflect the moistening of dry continental air entrained from a mid-latitude trough. These results demonstrate the power of rapid-response isotope monitoring to elucidate the structure and dynamics of water cycling within synoptic-scale systems and improve our understanding of storm evolution, hydroclimatological impacts, and paleo-storm proxies. PMID:24618882

Good, Stephen P.; Mallia, Derek V.; Lin, John C.; Bowen, Gabriel J.

2014-01-01

402

Stable Carbon Isotope Constraints on the Timing and Magnitude of Phytoplankton Blooms in San Francisco Bay  

NASA Astrophysics Data System (ADS)

Recent work on phytoplankton dynamics in San Francisco Bay (SFB) revealed new seasonal blooms. Historic observations (1978-1998) of chlorophyll a (Chl a) showed an annual pattern of short-lived spring blooms. In 1999, this pattern changed with the appearance of autumnal blooms in addition to the characteristic large vernal blooms. This change was attributed to decreases in bivalve mollusk populations concurrent with increases in macro invertebrate and vertebrate mollusk predators. Previous work, however, suggests that inter-annual variation in phytoplankton biomass is a function of river discharge. These observations suggest phytoplankton abundances in SFB reflect multiple forcing mechanisms and underscore the importance of understanding prehistoric variations in bloom dynamics. Here, we present stable isotope data from the exotic oyster Crassostrea gigas, which record the timing and magnitude of past phytoplankton blooms. These data may be useful for identifying patterns of phytoplankton bloom dynamics prior to instrumental observations. Stable oxygen (?18O) and carbon (?13C) isotope profiles from recent live-collected (2006) specimens of the oyster C. gigas collected in southern SFB were analyzed in conjunction with in situ records of environmental variability (water temperature and ?18Owater calculated from salinity). Their observed ?18Ocarb profiles are characterized by several unique features that correlate with predicted ?18Ocarb values calculated from water temperature and ?18Owater measurements indicating that these oysters were recruited at the end of 2001 or early in 2002. A prominent 1-2 spike characterizes the carbon isotope profile from each of these specimens. These positive excursions most likely reflect a large phytoplankton bloom, during which algae preferentially assimilated 12C, resulting in the enrichment of 13C in the dissolved inorganic carbon (DIC) of seawater. Furthermore, phytoplankton blooms may appear as positive spikes in a shells carbon isotope profile because bivalve shell ?13C, in part, reflects ?13CDIC. Chl a concentrations, collected by the USGS at two locations in southern SFB, show that a large phytoplankton bloom (Chl a >60 mg/m3) occurred in the spring of 2003. These data suggest C. gigas record phytoplankton blooms with Chl a concentrations >60 mg/m3. However, because several smaller blooms (Chl a 10-50 mg/m3) occurred during the lifetime of these individuals, it appears that 60 mg/m3 represents a threshold, below which blooms are not recorded. On the other hand, the inability to observe smaller blooms may reflect limits imposed by sample resolution. This study suggests prehistoric oystersand perhaps other bivalve mollusk speciesthat lived in SFB contain a valuable archive of large phytoplankton blooms. Furthermore, high-resolution sampling approaches may shed light on past smaller scale intra- and inter-annual bloom dynamics.

Goodwin, D.; Roopnarine, P. D.

2010-12-01

403

Molecular and stable carbon isotopic compositions of hopanoids in seep carbonates from the South China Sea continental slope  

NASA Astrophysics Data System (ADS)

The lipid biomarkers of hopanoids in cold seep carbonates from the South China Sea continental slope were investigated by gas chromatography-mass spectrometer (GC-MS) and gas chromatography-isotope ratio-mass spectrometer (GC-ir-MS). The distribution of hopanes/hopenes shows a preference for the biological 17?(H), 21?(H)-over the geological 17?(H), 21?(H)-configuration. This interpretation is in agreement with the strong odd-even preference of long-chain n-alkanes in those samples, suggesting that the ?? hopanes may be the early diagenetic products of biohopanoids and the ??, ?? configurations of hopanes were mainly derived from allochthonous sources contributing to the organic matter of the carbonates. In terms of hopanoid acids, the C30 to C33 17?(H), 21?(H)-hopanoid acids were detected with C32 17?(H), 21?(H)-hopanoid acid being the most abundant. However, there is a significant difference in stable carbon isotopic compostions of the C32 17?(H), 21?(H)-hopanoic acid among samples (-30.7 to -69.8). The ?13C values match well with the carbon isotopic compositions of SRB-derived iso-/anteiso-C15:0 fatty acids in the samples, which strongly depend on the carbon utilization types by microbe. The most abundant compound of hopanols detected in the samples, C30-17?(H), 21?(H)-hopanol, may be a good indicator of diagenetic product of type I methanotrophs. The molecular and carbon isotopic compositions of hopanoids demonstrate clearly that there is a combination contribution of both SRB and type I or type X methanotrophs to the source organism in the seep carbonates from the South China Sea continental slope.

Guan, Hongxiang; Sun, Yongge; Mao, Shengyi; Zhu, Xiaowei; Wu, Nengyou

2014-10-01

404

A Computational Framework for High-Throughput Isotopic Natural Abundance Correction of Omics-Level Ultra-High Resolution FT-MS Datasets  

PubMed Central

New metabolomics applications of ultra-high resolution and accuracy mass spectrometry can provide thousands of detectable isotopologues, with the number of potentially detectable isotopologues increasing exponentially with the number of stable isotopes used in newer isotope tracing methods like stable isotope-resolved metabolomics (SIRM) experiments. This huge increase in usable data requires software capable of correcting the large number of isotopologue peaks resulting from SIRM experiments in a timely manner. We describe the design of a new algorithm and software system capable of handling these high volumes of data, while including quality control methods for maintaining data quality. We validate this new algorithm against a previous single isotope correction algorithm in a two-step cross-validation. Next, we demonstrate the algorithm and correct for the effects of natural abundance for both 13C and 15N isotopes on a set of raw isotopologue intensities of UDP-N-acetyl-D-glucosamine derived from a 13C/15N-tracing experiment. Finally, we demonstrate the algorithm on a full omics-level dataset. PMID:24404440

Carreer, William J.; Flight, Robert M.; Moseley, Hunter N. B.

2013-01-01

405

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

PubMed Central

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 ?13C 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

Stanley, Steven M.

2010-01-01

406

Use of Stable Isotopes to Investigate Keratin Deposition in the Claw Tips of Ducks  

PubMed Central

Stable isotopes derived from the claws of birds could be used to determine the migratory origins of birds if the time periods represented in excised sections of claws were known. We investigated new keratin growth in the claws of adult female Lesser Scaup (Aythya affinis) by estimating the equilibration rates of stable isotopes (?13C, ?15N, and ?2H) from the breeding grounds into 1 mm claw tips. We sampled birds on their breeding ground through time and found that it took approximately 33.5 months for isotope values in most claw tips to equilibrate to isotope values that reflected those present in the environment on their breeding grounds. Results from this study suggest that isotopes equilibrate slowly into claw tips of Lesser Scaup, suggesting isotopes could potentially be used to determine the wintering grounds of birds. We suggest using controlled feeding experiments or longitudinal field investigations to understand claw growth and isotopic equilibration in claw tips. Such information would be valuable in ascertaining whether claw tips can be used in future studies to identify the migratory origins of birds. PMID:24282563

Hopkins, John B.; Cutting, Kyle A.; Warren, Jeffrey M.

2013-01-01

407

National uses and needs for separated stable isotopes in physics, chemistry, and geoscience research  

SciTech Connect

Present uses of separated stable isotopes in the fields of physics, chemistry, and the geosciences have been surveyed to identify current supply problems and to determine future needs. Demand for separated isotopes remains strong, with 220 different nuclides having been used in the past three years. The largest needs, in terms of both quantity and variety of isotopes, are found in nuclear physics research. Current problems include a lack of availability of many nuclides, unsatisfactory enrichment of rare species, and prohibitively high costs for certain important isotopes. It is expected that demands for separated isotopes will remain roughly at present levels, although there will be a shift toward more requests for highly enriched rare isotopes. Significantly greater use will be made of neutron-rich nuclides below A = 100 for producing exotic ion beams at various accelerators. Use of transition metal nuclei for nuclear magnetic resonance spectroscopy will expand. In addition, calibration standards will be required for the newer techniques of radiological dating, such as the Sm/Nd and Lu/Hf methods, but in relatively small quantities. Most members of the research community would be willing to pay considerably more than they do now to maintain adequate supplies of stable isotopes.

Zisman, M.S.

1982-01-01

408

Use of stable isotopes to investigate keratin deposition in the claw tips of ducks.  

PubMed

Stable isotopes derived from the claws of birds could be used to determine the migratory origins of birds if the time periods represented in excised sections of claws were known. We investigated new keratin growth in the claws of adult female Lesser Scaup (Aythya affinis) by estimating the equilibration rates of stable isotopes (? (13)C, ? (15)N, and ? (2)H) from the breeding grounds into 1 mm claw tips. We sampled birds on their breeding ground through time and found that it took approximately 3-3.5 months for isotope values in most claw tips to equilibrate to isotope values that reflected those present in the environment on their breeding grounds. Results from this study suggest that isotopes equilibrate slowly into claw tips of Lesser Scaup, suggesting isotopes could potentially be used to determine the wintering grounds of birds. We suggest using controlled feeding experiments or longitudinal field investigations to understand claw growth and isotopic equilibration in claw tips. Such information would be valuable in ascertaining whether claw tips can be used in future studies to identify the migratory origins of birds. PMID:24282563

Hopkins, John B; Cutting, Kyle A; Warren, Jeffrey M

2013-01-01

409

Monitoring water stable isotope composition in soils using gas-permeable tubing and infrared laser absorption spectroscopy  

NASA Astrophysics Data System (ADS)

The water stable isotopologues 1H2H16O and 1H218O are powerful tracers of processes occurring in nature. Their slightly different masses as compared to the most abundant water isotopologue (1H216O) affect their thermodynamic (e.g. during chemical equilibrium reactions or physical phase transitions with equilibration) and kinetic (liquid and vapor phases transport processes and chemical reactions without equilibration) properties. This results in measurable differences of the isotopic composition of water within or between the different terrestrial ecosystem compartments (i.e. sub-soil, soil, surface waters, plant, and atmosphere). These differences can help addressing a number of issues, among them water balance closure and flux partitioning from the soil-plant-atmosphere continuum at the field to regional scales. In soils particularly, the isotopic composition of water (?2H and ?18O) provides qualitative information about whether water has only infiltrated or already been re-evaporated since the last rainfall event or about the location of the evaporation front. From water stable isotope composition profiles measured in soils, it is also possible, under certain hypotheses, to derive quantitative information such as soil evaporation flux and the identification of root water uptake depths. In addition, water stable isotopologues have been well implemented into physically based Soil-Vegetation-Atmosphere Transfer models (e.g. SiSPAT-Isotope; Soil-Litter iso; TOUGHREACT) and have demonstrated their potential. However, the main disadvantage of the isotope methodology is that, contrary to other soil state variables that can be monitored over long time periods, ?2H and ?18O are typically analyzed following destructive sampling. Here, we present a non-destructive method for monitoring soil liquid water ?2H and ?18O over a wide range of water availability conditions and temperatures by sampling and measuring water vapor equilibrated with soil water using gas-permeable polypropylene tubing and a cavity ring-down laser absorption spectrometer. By analyzing water vapor ?2H and ?18O sampled with the tubing from a fine sand for temperatures ranging between 8-24 C, we demonstrate that (i) our new method is capable of monitoring ?2H and ?18O in soils online with high precision and, after calibration, also with high accuracy, (ii) our sampling protocol enabled detecting changes of ?2H and ?18O following non-fractionating addition and removal of liquid water and water vapor of different isotopic compositions, and (iii) the time needed for the tubing to monitor these changes is compatible with the observed variations of ?2H and ?18O in soils under natural conditions.

Rothfuss, Youri; Vereecken, Harry; Brggemann, Nicolas

2013-04-01

410

Drivers of precipitation stable oxygen isotope variability in an alpine setting, Snowy Mountains, Australia  

NASA Astrophysics Data System (ADS)

archives that preserve a stable isotopic signature are routinely used to reconstruct palaeoenvironmental conditions. Isotopic values of precipitation are known to be influenced by factors such as the amount and type of precipitation, moisture pathway, landscape and terrain factors, and processes associated with precipitation formation and deposition. This study investigates oxygen isotopic variability using real-time rain and snow precipitation data from a moderate altitude (<2250 m above sea level), Southern Hemisphere alpine environment, where the causes of isotopic variability are largely unknown. Previous research at Global Network of Isotopes in Precipitation sites skewed toward rain precipitation, low-altitude, predominantly coastal locations identified amount effects as the dominant explanation of isotopic variability in southern Australia. This study based on within- and between-event real-time sampling finds that the origin of moisture and terrain effects are the dominant cause of isotopic variability in this alpine region, with little evidence of amount effects. Rainfall that originated from similar Southern Ocean latitudes showed a consistent (moderate) isotopic signature (?18O -6.5 to -8). Depleted isotopic signatures are associated with prefrontal activity and intense circulation such as east coast lows. Localized thunderstorms have a more neutral isotopic signature. A windward to leeward depletion (-0.5 ?18O) and an elevation impact (-0.5 ?18O 100 m-1) were found also. These results have significant implications for understanding atmospheric drivers of isotopic variability from which oxygen isotope-based palaeoclimate reconstruction is informed in regions with complex topography and geographically diverse moisture pathways such as the Australian Alps.

Callow, Nik; McGowan, Hamish; Warren, Loredana; Speirs, Johanna

2014-03-01

411

Grasland Stable Isotope Flux Measurements: Three Isotopomers of Carbon Dioxide Measured by QCL Spectroscopy  

NASA Astrophysics Data System (ADS)

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 Swit