A short-term simulated weathering experiment was performed on two crude oils and two heavy fuel oils under natural conditions to evaluate the effects of natural weathering processes by using gas chromatography mass spectrometry combined with gas chromatography isotopic ratio mass spectrometry. The results of diagnostic ratios of n-alkanes show that only odd to even predominance (OEP1, OPE2) and carbon preference index (CPI) remain stabilized during the 28 d weathering process, but they cannot effectively distinguish the four types of oils. Statistical analyses based on paired sample t-test and principal component analysis (PCA) revealed that stable carbon isotope compositions of n-alkanes in the four studied oils have no significant changes over the weathering time, and that the carbon isotope discrimination (Delta delta C-13) of n-alkanes is , 3 parts per thousand. We have provided evidence that the stable carbon isotope compositions of n-alkanes compared to n-alkanes diagnostic ratios ...

Helichrysum italicum (Roth) G. Don fil. subsp. italicum oils, coming from Sicily and Corsica and growing up, at equal geographical area, at the same edaphic and climatic conditions, were investigated by GC-MS, GC-FID and gas chromatography carbon isotope ratio mass spectrometry (GC-C-IRMS). GC-MS and GC-FID analyses on the oils terpene fraction have evidenced two different compositional finger prints (chemotypes). Investigating the carbon isotope ratio of the main and common terpene compounds, were also highlighted different plants genetic behaviors. The i-stds elaboration has permitted to investigate on the plants genetic changes, taking into account only the secondary biogenetic pathways, in which the terpenes formation occurs ...

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 seat analyses showed the primary food to be microtine rodents and reindeer. The Icelandic samples included foxes from both coastal and inland habitats, the Swedish sample came from an inland area, and the Greenland sample from coastal sites. The spatial variation in the isotopic pattern followed a basic division between marine and terrestrial sources of protein. Arctic foxes from inland sites had delta(13)C values of -21.4 (Ice land) and -20.4 parts per thousand (Sweden), showing typical terrestrial values. Coastal foxes from Greenland had typical marine Values of -14.9 parts per thousand, whereas coastal foxes from Iceland had intermediate values of -17.7 parts per ...

The increasing number of bomb attacks involving improvised explosive devices, as well as the nature of the explosives, give rise to concern among safety and law enforcement agencies. The substances used in explosive charges are often everyday products diverted from their primary licit applications. Thus, reducing or limiting their accessibility for prevention purposes is difficult. Ammonium nitrate, employed in agriculture as a fertiliser, is used worldwide in small and large homemade bombs. Black powder, dedicated to hunting and shooting sports, is used illegally as a filling in pipe bombs causing extensive damage. If the main developments of instrumental techniques in explosive analysis have been constantly pushing the limits of detection, their actual contribution to the investigation of explosives in terms of source discrimination is limited. Forensic science has seen the emergence of a new technology, isotope ratio mass spectrometry (IRMS), that shows promising results. Its very f

Stable carbon isotope analyses of the humin fraction of the soil organic matter were conducted on more than 160 soil profiles from Tikal, Guatemala. The profiles were collected from near areas associated with the earthworks of Tikal; an ancient ditch and parapet construction hypothesized to have formed ancient boundaries of the polity. In addition to the isotope analyses, the physical and chemical characteristics of the horizons were determined. Maize, a C4 plant, formed an integral part of the ancient Maya diet and is the only known C4 plant cultivated by the Maya. Prior to and subsequent to the ancient Maya occupation of Tikal, the landscape was dominated by C3 forest vegetation. Over the centuries C4 plant biomass including rhizodeposition decomposed to form soil organic matter that contains a distinct C4 signature reflecting the vegetation history of the area. Forested areas anciently cleared for agriculture were identified through interpretation of significant isotopic shifts that signaled past

Arı́stegui J, Duarte CM, Agustı́ S, Doval M, Álvarez-Salgado XA, Hansell DA. 2002. Dissolved organic carbon support of respiration in the dark ocean. Science. 298(5600):1967-1967. doi:10.1126/science.1076746.. Boyd PW, Sherry ND, Berges JA, Bishop JKB, Calvert SE, Charette MA, Giovannoni SJ, Goldblatt R, Harrison PJ, Moran SB, et al. 1999. Transformations of biogenic particulates from the pelagic to the deep ocean realm. Deep Sea Res, Part II. 46(11):2761-2792. doi:10.1016/S0967-0645(99)00083-1.. Carter JF, Barwick VJ, editors. 2011. Good practice guide for isotope ratio mass spectrometry. 1st edition. Bristol: FIRMS.. Cavan EL, Trimmer M, Shelley F, Sanders R. 2017. Remineralization of particulate organic carbon in an ocean oxygen minimum zone. Nat Commun. 8(1):1-9. doi:10.1038/ncomms14847.. Cifuentes LA, Sharp JH, Fogel ML. 1988. Stable carbon and nitrogen isotope biogeochemistry in the Delaware estuary: Carbon and nitrogen isotopes. Limnol Oceanogr. 33(5):1102-1115. ...

The major source of carbon to the bacterial community in a seagrass (Thalassia testudinum) dominated region of Lower Laguna Madre, Texas was determined with the isotopic composition of bacterial phospholipid fatty acids. Rough estimates of bacterial abundance were also obtained from total phospholipid fatty acid concentrations. Core samples came from three differing habitat types consisting of a bare area, a transitional area, and a vegetated area. Five depth intervals of 0-0.5 cm, 0.5-2.5 cm, 4.5-6.5 cm, 8.5-10.5 cm, and 18.5-20.5 cm from each core were used for analyses. Bacterial abundance was significantly higher in the vegetated habitat compared with bare or transitional habitats, which showed little difference from one another. The stable carbon isotope ratios ([ð]¹³C) of branched chain fatty acids, iso- and anteiso-15:0 (i&a15:0) found only in bacteria were used to assess carbon utilization. The [ð]¹³C of total organic carbon (TO¹³C) and the ubiquitous fatty acid 16:0 were used as ...

Carbon isotope effects were investigated for the reaction catalyzed by the glycine decarboxylase complex (GDC; EC 2.1.2.10). Mitochondria isolated from leaves of pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) were incubated with glycine, and the CO2 evolved was analyzed for the carbon isotope ratio (delta C-13). Within the range of parameters tested (temperature, pH, combination of cofactors NAD(+), ADP, pyridoxal 5-phosphate), carbon isotope shifts of CO2 relative to the C-1-carboxyl carbon of glycine varied from +14 parts per thousand to -7 parts per thousand. The maximum effect of cofactors was observed for NAD(+), the removal of which resulted in a strong C-12 enrichment of the CO2 evolved. This indicates the possibility of isotope effects with both positive and negative signs in the GDC reaction. The measurement of delta C-13 in the leaves of the GDC-deficient barley ( Hordeum vulgare L.) mutant (LaPr 87/30) plants indicated that photorespiratory carbon isotope fractionation, ...

We investigated the relationships between foliar stable carbon isotope discrimination (Delta), % foliar N, and predawn water potentials ((water potential symbol)pd) and midday stomatal conductance (g(s)) of Larrea tridentata across five Mojave Desert soils with different age-specific surface and sub-surface horizon development and soil hydrologies. We wished to elucidate how this long-lived evergreen shrub optimizes leaf-level physiological performance across soils with physicochemical characteristics that affect the distribution of limiting water and nitrogen resources. We found that in young, coarse alluvial soils that permit water infiltration to deeper soil horizons, % foliar N was highest and Delta, g(s) and psgrpd were lowest, while %N was lowest and Delta, g(s) and (water potential symbol)pd were highest in fine sandy soils; Larrea growing in older soils with well-developed surface and sub-surface horizons exhibited intermediate values for these parameters. Delta showed negative linear

Across a wide range of environmental conditions, forest types and tree species we found carbon isotope ratios of wood to be a strong and reliable indicator of past drought occurrence (Fig. 2a). However, despite this clear physiological signal of drought on δ13C, we only found a weak and context-dependent effect of these same drought events on tree growth (Fig. 2b). Previous studies have suggested that the relationship between carbon isotopes and growth might not be a simple one (Ferrio et al. 2003; Peñuelas et al. 2008; Jansen et al. 2013; Hentschel et al. 2016; Shestakova et al. 2017), but to our knowledge none had explored the relationship across a broad enough range of species and environmental conditions to draw this conclusion robustly. The relatively small declines in growth we observed in response to drought suggest that most European tree species are - on average - able to maintain growth under conditions of low soil water availability.. This is not to say that water availability is ...

TY - JOUR. T1 - Measurement of δ18O and δ2H values of fluid inclusion water in speleothems using cavity ring-down spectroscopy compared with isotope ratio mass spectrometry. AU - Arienzo, Monica M.. AU - Swart, Peter K.. AU - Vonhof, Hubert B.. N1 - Copyright: Copyright 2013 Elsevier B.V., All rights reserved.. PY - 2013/12/15. Y1 - 2013/12/15. N2 - RATIONALE The hydrogen and oxygen isotopic analyses (δ2H and δ18O values) of water trapped within speleothem carbonate (fluid inclusions) have traditionally been conducted utilizing dual-inlet isotope ratio mass spectrometry (IRMS) or continuous-flow (CF)-IRMS methods. The application of cavity ring-down spectroscopy (CRDS) to the δ2H and δ18O analysis of water in fluid inclusions has been investigated at the University of Miami as an alternative method to CF-IRMS. METHODS An extraction line was developed to recover water from the fluid inclusions consisting of a crusher, sample injection port and an expansion volume (either 100 or 50 cm3) ...

Enamel stable carbon isotope analyses were conducted on the large fossil ape Gigantopithecus blacki and an associated mammalian megafauna from Longgudong Cave in Jianshi and Juyuandong Cave in Liuchen

NUCLEAR MAGNETIC RESONANCE IMAGING + NUCLEAR MAGNETIC RESONANCE TOMOGRAPHY (MEDICAL DIAGNOSTICS); NMR-MIKROSKOPIE, NMR-ABBILDUNDSVERFAHREN; CARBON-13 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; NUTRITION + NUTRITIONAL SCIENCE; BONE MARROW (CYTOLOGY, HISTOLOGY); KNOCHENMARK (CYTOLOGIE, HISTOLOGIE); ERNÄHRUNG + ERNÄHRUNGSWISSENSCHAFT; FETTSÄUREN (BIOCHEMIE); FATTY ACIDS (BIOCHEMISTRY); MUSKELZELLEN (CYTOLOGIE, HISTOLOGIE); KOHLENSTOFF-13-KERNRESONANZSPEKTROSKOPIE; KERNSPINRESONANZ-ABBILDUNGSVERFAHREN + KERNSPINRESONANZ-TOMOGRAPHIE (MEDIZINISCHE DIAGNOSTIK); MUSCLE CELLS (CYTOLOGY, HISTOLOGY); NMR MICROSCOPY, NMR ...

TY - GEN. T1 - Carbon isotope signatures and their possible link to upwelling, Middle Mississippian crinoidal-bryozoan carbonates, Illinois Basin. AU - Lasemi, Z.. N1 - hand-typed from author-received information. PY - 2018. Y1 - 2018. KW - ISGS. M3 - Conference contribution. SP - 88. BT - Book of Abstracts. CY - Quebec City, Canada. ER - ...

In this study, we analyzed settling particles collected from March 2011 to February 2012 for long-chain n-alkanes and their stable carbon isotope ratio (δ13C) to investigate sources of terrestrial organic carbon in the Ulleung basin (East Sea). The settling particles were collected with 10 to 17-day intervals at 1000 m and 2300 m water depths. In general, the n-alkanes showed strong odd carbon number predominance at both water depths with higher fluxes of long-chain n-alkanes (C25-C35, 0.4-12.0 μg/m2/day at 1000 m water depth and 0.7-13.6 μg/m2/day at 2300 m water depth) than those of short-chain n-alkanes (C15-C23, 0.04-1.1 μg/m2/day at 1000 m water depth and 0.1-0.9 μg/m2/day at 2300 m water depth). The δ13C signatures of n-C27, n-C29, and n-C31 at 1000 m and 2300 m water depths were -31.0±0.5‰, -32.1±0.4‰, -32.4±0.8‰ and -30.9±0.9‰, -31.7±0.5‰, -32.3±0.4‰, respectively, indicating a large contribution of C3 plant as the main source of n-alkanes. The carbon Preference ...

0057] The presence of 14C, the content of biomaterial, the content of biocarbon or the content of organic carbon of renewable origin of a material is determined on the basis of standards ASTM D 6866 (ASTM D 6866-06) and ASTM D 7026 (ASTM D 7026-04). Standard ASTM D 6866 relates to Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis, whereas standard ASTM D 7026 relates to Sampling and Reporting of Results for Determination of Biobased Content of Materials via Carbon Isotope Analysis. The second standard refers in its first paragraph to the first standard. The first standard describes a test for measuring the 14C/12C ratio of a sample and compares it with the 14C/12C ratio of a reference sample of 100% renewable origin, to give a relative percentage of C of renewable origin in the sample. The standard is based on the same concepts as 14C dating, but without applying dating equations. The ratio thus calculated is designated ...

Scheele, N. and Hoefs, J. (1992): Carbon isotope fractionation between calcite, graphite and CO2 an experimental study , Contrib Mineral Petrol ...

Riebesell, U. (1996): Carbon isotope fractionation by marine phytoplankton , Yigal Allon Kinneret Limnological Laboratory, Tiberias, Israel. Dezember 1996 ...

We present new carbon and oxygen isotope curves from sections in the Bakony Mts. (Hungary), constrained by biostratigraphy and magnetostratigraphy in order to evaluate whether carbon isotopes can provide a tool to help establish and correlate the last system boundary remaining undefined in the Phanerozoic as well provide data to better understand the carbon cycle history and environmental drivers during the Jurassic-Cretaceous interval. We observe a gentle decrease in carbon isotope values through the Late Jurassic. A pronounced shift to more positive carbon isotope values does not occur until the Valanginian, corresponding to the Weissert event. In order to place the newly obtained stable isotope data into a global context, we compiled 31 published and stratigraphically constrained carbon isotope records from the Pacific, Tethyan, Atlantic, and Boreal realms, to produce a new global δ13C stack for the Late Oxfordian through Early Hauterivian interval. Our new data from Hungary is consistent ...

Diverse interpretations have been made of carbon isotope time series in speleothems, reflecting multiple potential controls. Here we study the dynamics of 13C and 12C cycling in a particularly well-constrained site to improve our understanding of processes affecting speleothem δ13C values. The small, tubular Grotta di Ernesto cave (NE Italy) hosts annually-laminated speleothem archives of climatic and environmental changes. Temperature, air pressure, pCO2, dissolved inorganic carbon (DIC) and their C isotopic compositions were monitored for up to five years in soil water and gas, cave dripwater and cave air. Mass-balance models were constructed for CO2 concentrations and tested against the carbon isotope data. Air advection forces winter pCO2 to drop in the cave air to ca. 500 ppm from a summer peak of ca. 1500 ppm, with a rate of air exchange between cave and free atmosphere of approximately 0.4 days. The process of cave ventilation forces degassing of CO2 from the dripwater, prior to any ...

The Waikato Stable Isotope Unit (WSIU) offers precision analyses of isotopes of carbon and nitrogen in biological, geological, and chemical materials by isotope ratio mass spectrometry. Isotopic abundance analysis is carried out on two fully automated Europa Scientific 20/20 isotope analysers. Materials may be submitted as solids, liquids, or gases, for example, for breath analyses. Precision analyses of carbon and nitrogen content in solid or liquid samples are also provided with a LECO TruSpec Carbon/Nitrogen Determinator fitted with an autosampler for liquids.. The WSIU provides commercial analyses and also services the needs of scientists at the University of Waikato and their collaborators, promoting the use of stable isotopes in all branches of research. Staff are highly experienced in the use of stable isotopes, both natural abundance and enriched tracers, particularly in biological and environmental research. In 2006 the WSIU was accredited by the International Atomic Energy Agency for ...

Fossils of many species are common all the way across the landscape, Ambrose said. But this species is missing in action from the east side of the distribution.. Isotopic analysis of teeth found on the site gave a more complete picture of the habitat of the animals that lived and died there, Ambrose said.. The distribution of plant carbon isotope ratios conveniently separates out grasslands from forests, he said. And it also separates out grazing animals, like zebras, from browsing animals that eat the leaves off of trees, like giraffes.. The distribution of the fossil browsers and grazers echoed that of the habitat, he said.. On the west we find lots of Ardipithecus fossils and theyre associated with a lot of woodland and forest animals, he said. And then theres a break; Ardipithecus and most of the monkeys that live in trees disappear, and grass-eating animals become more abundant.. The carbon isotope ratios of the Ardipithecus teeth also tell the story of a woodland creature, he ...

On trouve des séquences de marbre en abondance dans la partie de la Province du Grenville du bouclier canadien traversant de la chaîne des monts Adirondack, vers lOntario, jusque dans les Laurentides, au Québec, sur une distance de 300 km. Dans la région du lac Otter, dans la partie occidentale du Québec, des unités majeures de marbre, de toute évidence des séquences de calcaire à lorigine, contiennent des assemblages de calcite, dolomite, olivine, minéraux du groupe de la humite, pyroxène calcique, amphibole calcique, biotite, graphite, ainsi que serpentine et brucite rétrogrades, tandis que les unités mineures de marbre, dorigine métasomatique, contiennent des assemblages de calcite (rose), pyroxène calcique, amphibole calcique, biotite, grenat, feldspath potassique, scapolite, et titanite. La composition isotopique de loxygène et du carbone dans la calcite des unités majeures de marbre (δ18OVSMOW dans lintervalle entre 28 et 17‰; δ13CPDB-1 dans ...

Håkon Mosby Mud Volcano (HMMV, SW Barents Sea slope, 1280 m) is one of the numerous cold methane-venting seeps existing along the continental margins. Analyses of videoguided core samples revealed extreme differences in the diversity and density of the metazoan meiobenthic communities associated with the different sub-habitats (centre, microbial mats, Pogonophora field, outer rim) of this mud volcano. Diversity was lowest in the sulphidic, microbial mat sediments that supported the highest standing stock, with unusually high densities (11 000 ind. 10 cm-2) of 1 nematode species related to Geomonhystera disjuncta. Stable carbon isotope analyses revealed that this nematode species was thriving on chemosynthetically derived food sources in these sediments. Ovoviviparous reproduction has been identified as an important adaptation of parents securing the survival and development of their brood in this toxic environment. The proliferation of this single species in exclusive association with ...

We measure stable isotope ratios of carbon and nitrogen in organic matrix using conventional isotope ratio mass spectrometers. For a price offer, please contact the corresponding network partner. Animal tissue: --, Dr. Christian C. Voigt at: [email protected] Plant material: --, Dr. Zachary Kayler at: [email protected] Historic samples --, Dr. Ulrich Struck at: [email protected] ...

The Chrono Centre undergo Isotope Ratio Mass Spectrometry (EA-IRMS) using a Thermo Delta V Advantage IRMS machine and accompanying Flash 112 elemental analyser.

This publication was developed by an international group of experts as an integral part of the IAEAs efforts to contribute to the transfer of technology and knowledge in nutrition. Its aim is to assist Member States in their efforts to combat malnutrition by facilitating the use of relevant nuclear techniques. The stable (non-radioactive) isotope technique has been developed to assess intake of human milk in breastfed infants. The practical application of the stable isotope technique, based on analysis of deuterium by Fourier transform infrared spectrometry (FTIR), is presented in this book.. ...

As demonstrated by the chapters in this short course, stable isotope techniques are an important tool in almost every branch of the earth sciences. Central to many of these applications is a quantitative understanding of equilibrium isotope partitioning between substances. Indeed, it was Harold Ureys (1947) thermodynamically based estimate of the temperature-dependence of 18O/16O fractionation between calcium carbonate and water, and a recognition of how this information might be used to determine the temperatures of ancient oceans, that launched the science of stable isotope geochemistry. The approach pioneered by Urey has since been used to estimate temperatures.... ...

All 3795 co-registered samples were analyzed for their soluble major anion content (Cl-, NO3-, SO42-) by ion chromatography (IC) and for trace elements (Na, Mg, Ca, Sr, Cd, Cs, Ba, La, Ce, Pr, Pb, Bi, U, As, Al, S, Ti, V, Cr, Mn, Fe, Co, Cu, Zn) by inductively coupled plasma sector field mass spectrometry (ICP-MS). Major anions were analyzed on a Dionex DX-500 ion chromatograph coupled to a Gilson autosampler, and concentrations are reported in ug/L (ppb). Trace elements analyses were performed with the University of Maine Thermo Electron Element2 ICP-MS coupled to a Cetac Model ASX- 260 autosampler. Isotopes were measured in low and medium resolution (GIVE range ppt-ppq). The ICP-MS samples were acidified to 1% with double-distilled HN03 under a class-100 High Efficiency Particle Air (HEPA) clean bench and allowed to react with the acid for approximately 1 week before being frozen. Approximately every fifth sample (713 total) was analyzed for dD by isotope ratio mass spectrometry (IRMS) using a ...

As most of the uses of plants are intimately linked to their metabolic output or activity, there is a renewed interest in understanding the behavior and regulation of plant metabolic networks. The only direct measure of metabolic activity, and the facet most closely related to biological function, is flux through the metabolic network (Libourel and Shachar-Hill, 2008). There has been a considerable research effort in the last few years to develop and refine methods that allow fluxes in large metabolic networks to be determined. The best established of these methods, steady-state metabolic flux analysis (MFA), involves measuring the redistribution of a supplied stable isotope, usually 13C, at metabolic and isotopic steady state (Ratcliffe and Shachar-Hill, 2006; Allen et al., 2009a). Flux maps of a range of heterotrophic plant cells and tissues have been produced, providing information on the operation of different flux modes (Sriram et al., 2004, 2007; Schwender et al., 2006; Allen et al., ...

STICKSTOFFORGANISCHE UMWELTSCHADSTOFFE; ABBAU, ZERSETZUNG, UMWANDLUNG, PERSISTENZ VON UMWELTSCHADSTOFFEN (UMWELTPROBLEME); TRIAZIN-DERIVATE (PESTIZIDWIRKSTOFFE); REDUKTION (CHEMISCHE REAKTIONEN); PHOTOCHEMISCHE REAKTIONEN (CHEMISCHE REAKTIONEN); ISOTOPIEEFFEKT (CHEMISCHE KINETIK); STICKSTOFF-15-ISOTOP; NITROGEN ORGANIC ENVIRONMENTAL POLLUTANTS; DEGRADATION, DECOMPOSITION, TRANSFORMATION, PERSISTENCE OF POLLUTANTS (ENVIRONMENTAL PROBLEMS); TRIAZINE-DERIVATIVES (PESTICIDE AGENTS); REDUCTION (CHEMICAL REACTIONS); PHOTOCHEMICAL REACTIONS (CHEMICAL REACTIONS); ISOTOPE EFFECT (CHEMICAL KINETICS); NITROGEN-15- ...

The first one is the mineralogical and geochemical investigation of ore and non-ore deposits in Slovakia and elsewhere in the World. Traditional analytical methods (electron probe micro-analysis, X-ray diffraction) are employed to characterize raw and dump materials mineralogically, chemically and structurally. Apart from this, fluid inclusion microthermometry, isotope ratio mass spectrometry combined with thermodynamic modeling are employed to decipher age and formation conditions of raw materials. This approach was applied to genetic studies of polymetallic ore deposits of Central Slovakian volcanics, magnesite, siderite, barite and stibnite deposits in Ore Mountains of Slovakia, and a polymetallic ore deposit in Kosovo. Recently, we are studying genesis of a phosphate deposit in Mozambique ...

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We hypothesize that the rapid onset of the carbon isotope excursion (CIE) at the Paleocene/Eocene boundary (V55 Ma) may have resulted from the accretion of a significant amount of 12C-enriched carbon from the impact of a V10 km comet, an event that would also trigger greenhouse warming leading to the Paleocene/Eocene thermal maximum and, possibly, thermal dissociation of seafloor methane hydrate. Indirect evidence of an impact is the unusual abundance of magnetic nanoparticles in kaolinite-rich shelf sediments that closely coincide with the onset and nadir of the CIE at three drill sites on the Atlantic Coastal Plain. After considering various alternative mechanisms that could have produced the magnetic nanoparticle assemblage and by analogy with the reported detection of iron-rich nanophase material at the Cretaceous/Tertiary boundary, we suggest that the CIE occurrence was derived from an impact plume condensate. The sudden increase in kaolinite is thus thought to represent the redeposition on the

We are investigating how the carbon isotope composition of fossil land plants and fossil organic matter can be used to infer climate change in ancient ecosystems.. M.T. Rabanus-Wallace, M.J. Wooller, G.D. Zazula, E. Shute, A.H. Jahren, P. Kosintsev, J.A. Burns, J. Breen, B. Llamas and A. Cooper. 2017. Megafaunal isotopes reveal role of increased moisture on rangeland during Late Pleistocene extinctions. Nature Ecology & Evolution, 1, 0125, DOI: 10.1038/s41559-017-0215. (view/download pdf). B.A. Schubert% and A.H. Jahren. 2013. Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric CO2 levels. Nature Communications, 4:1653, DOI: 10.1038/ncomms2659. (view/download pdf). A.H. Jahren, B.A. Schubert%, L. Marynowski and J.P. Wilson*. The carbon isotope organic geochemistry of Early Ordovician rocks from the Annascaul Formation, County Kerry. Irish Journal of Earth Sciences, 31: 1-12; doi: 10.3318/IJES.2013.31. (view/download pdf).. G.J. Retallack and A.H. ...

We are investigating how the carbon isotope composition of fossil land plants and fossil organic matter can be used to infer climate change in ancient ecosystems.. M.T. Rabanus-Wallace, M.J. Wooller, G.D. Zazula, E. Shute, A.H. Jahren, P. Kosintsev, J.A. Burns, J. Breen, B. Llamas and A. Cooper. 2017. Megafaunal isotopes reveal role of increased moisture on rangeland during Late Pleistocene extinctions. Nature Ecology & Evolution, 1, 0125, DOI: 10.1038/s41559-017-0215. (view/download pdf). B.A. Schubert% and A.H. Jahren. 2013. Reconciliation of marine and terrestrial carbon isotope excursions based on changing atmospheric CO2 levels. Nature Communications, 4:1653, DOI: 10.1038/ncomms2659. (view/download pdf). A.H. Jahren, B.A. Schubert%, L. Marynowski and J.P. Wilson*. The carbon isotope organic geochemistry of Early Ordovician rocks from the Annascaul Formation, County Kerry. Irish Journal of Earth Sciences, 31: 1-12; doi: 10.3318/IJES.2013.31. (view/download pdf).. G.J. Retallack and A.H. ...

Abstract: We construct an interaction between a (2,0) tensor multiplet in six dimensions and a self-dual string. The interaction is a sum of a Nambu-Goto term, with the tension of the string given by the modulus of the scalar fields of the tensor multiplet, and a non-local Wess-Zumino term, that encodes the electromagnetic coupling of the string to the two-form gauge field of the tensor multiplet. The interaction is invariant under global (2,0) supersymmetry, modulo the equations of motion of a free tensor multiplet. It is also invariant under a local fermionic kappa-symmetry, as required by the BPS-property of the string ...

Natural-abundance 13C nuclear magnetic resonance spectra of ten common nucleotides in neutral, aqueous solutions have been determined and interpreted. The spectra of two of these substances were also determined in acidic solutions, and several of the carbon chemical shifts were found to depend markedly on pH. Within the limited range of concentrations employed, there were observed no carbon chemical-shift changes which could be ascribed to base-stacking or base-pairing phenomena. ...

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Heterogeneous and homogeneous processes in the formation of diamond at low pressures, where diamond is a metastable modification of carbon, are discussed. Data on the kinetics of the growth of diamond from hydrocarbons under conditions which give codeposition with graphite are reported, together with data on the influence of hydrogen on this process and on the resulting fractionation of the stable carbon isotopes. Chemical and plasma-chemical methods of preparing diamond and diamond-like layers are discussed, as well as methods based on the use of atomic and ionic beams. The most recent theoretical and experimental results on the homogeneous formation of diamond in the gas phase are presented ...

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to 1) assess winter habitat dynamics and validate the use of stable carbon isotopes as a measure of ... effects from winter habitat on arrival timing, reproduction, and post-fledging survival, and 3) explore ... carry-over effects between breeding events, molt, and subsequent winter habitat use. Combined, my results .... ...

to 1) assess winter habitat dynamics and validate the use of stable carbon isotopes as a measure of ... effects from winter habitat on arrival timing, reproduction, and post-fledging survival, and 3) explore ... carry-over effects between breeding events, molt, and subsequent winter habitat use. Combined, my results .... ...

We present an advanced system for on-line position-specific carbon isotope analysis. The main limitation of on-line intramolecular isotope ratio measurements has been that optimal pyrolytic fragments are obtained mostly at temperatures where the analyte has not completely reacted. As a result of undetermined isotopic fractionation, the isotopic signatures of the pyrolysis products are not strictly equal to these of the equivalent moieties in the parent molecule. We designed a pyrolytic unit in which both temperature and reaction time are variable parameters, enabling determination of the enrichment factor of the pyrolysis at optimal temperature by construction of a Rayleigh plot. In the case of methyl tert-butyl ether (MTBE) presented here, a pre-pyrolysis fractionation of MTBE leading to a depletion of 0.9 parts per thousand was discovered and the enrichment factor of the optimal pyrolysis reaction was determined at -1.7 parts per thousand. Absolute delta C-13 values of two functional groups ...

0036]The stable carbon isotope ratio (13C/12C) provides a complementary route to source discrimination and apportionment. The 13C/12C ratio in a given biosourced material is a consequence of the 13C/12C ratio in atmospheric carbon dioxide at the time the carbon dioxide is fixed and also reflects the precise metabolic pathway. Regional variations also occur. Petroleum, C3 plants (the broadleaf), C4 plants (the grasses), and marine carbonates all show significant differences in 13C/12C and the corresponding δ 13C values. Furthermore, lipid matter of C3 and C4 plants analyze differently than materials derived from the carbohydrate components of the same plants as a consequence of the metabolic pathway. Within the precision of measurement, 13C shows large variations due to isotopic fractionation effects, the most significant of which for the instant invention is the photosynthetic mechanism. The major cause of differences in the carbon isotope ratio in plants is closely associated with differences ...

In order to investigate mid-Cretaceous terrestrial climates of low paleolatitudes, Moroccan, Tunisian and Brazilian vertebrate apatites have been analyzed for their oxygen and carbon isotope compositions of phosphates (delta O-18(p)) and carbonates (delta O-18(c), delta C-18(c)). At each site, coexisting theropod dinosaurs, titanosaurid sauropods, pterosaurs, crocodilians, turtles and fish have distinct delta O-18(p) and delta C-18(c) values reflecting their ecologies, diets and foraging environments. Oxygen isotope compositions of surface waters (delta O-18(w)) estimated from turtle and crocodile delta O-18(p) values range from -5.0 +/- 1.0 parts per thousand to -2.4 +/- 1.0 parts per thousand, which do not differ from mean annual rainwater values occurring today under inter-tropical sub-arid to arid climates. High water temperatures ranging from 21 +/- 6 degrees C to 34 +/- 2 degrees C deduced from fish delta O-18(p) values are in agreement with those published for mid-Cretaceous low ...

This article presents an overview of the history of Caribbean archaeological carbon and nitrogen stable isotope studies, a history that is paradoxically notable both for the precociousness of its first appearance and the subsequent dearth of large and meaningful studies. It provides a synopsis of the methodological underpinnings of paleodietary reconstruction by stable isotope analysis and discusses some of the unique challenges encountered in the use of this technique in Caribbean contexts. After reviewing some of the more meaningful studies of Caribbean archaeological materials, the article concludes with some thoughts on future prospects for the use of C and N stable isotope analysis for paleodietary reconstruction in archaeological research in the Caribbean Basin.

TY - GEN. T1 - Stable isotope analysis of breath using the optogalvanic effect. AU - Murnick, Daniel E.. AU - Colgan, M. J.. AU - Lie, H. P.. AU - Stoneback, D.. PY - 1996/1/1. Y1 - 1996/1/1. N2 - 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 ...

1.During infusion of [5-15N]glutamine in patients with gastrointestinal cancer we unexpectedly observed a gradual decrease in time of the appearance rate (Ra) of glutamine in plasma. Here we investigate whether the failure to achieve a plateau isotopic enrichment in plasma is, among other factors, due to incomplete equilibration of the glutamine tracer with the large intramuscular free glutamine pool.. 2.Plasma and intramuscular glutamine enrichment were measured during 6-11 ;h infusions of L-[5-15N]glutamine and L-[1-13C]glutamine in post-absorptive patients admitted to hospital for elective abdominal surgery. L-[1-13C]Leucine and L-[ring-2H5]phenylalanine were infused to measure the proportion of glutamine appearing in plasma directly due to its release from protein.. 3.The glutamine tracer entered muscle, but the rise in intramuscular glutamine enrichment was small, presumably as a result of the enormous size of the intramuscular glutamine pool and the limited speed of entry of glutamine into ...

Sudden pulse-like events of rapidly increasing CO2-efflux occur in soils under seasonally dry climates in response to rewetting after drought. These occurrences, termed Birch effect, can have a marked influence on the ecosystem carbon balance. Current hypotheses indicate that the Birch pulse is caused by rapidly increased respiration and mineralization rates in response to changing moisture conditions but the underlying mechanisms are still unclear. Here, we present data from an experimental field study using straight-forward stable isotope methodology to gather new insights into the processes induced by rewetting of dried soils and evaluate current hypotheses for the Birch-CO2-pulse. Two irrigation experiments were conducted on bare soil, root-free soil and intact vegetation during May and August 2005 in a semi-arid Mediterranean holm oak forest in southern Portugal. We continuously monitored CO2-fluxes along with their isotopic compositions before, during and after the irrigation. d13C ...

We have in our lab a Finnegan 253 isotope ratio mass spectrometer with GC-combustion interface, a Finnegan Delta Plus IRMS with dual inlet and continuous flow GC interfaces, two standalone HP 6890 GCs, and a Pfeiffer quadrupole mass spectrometer. There is also an Ionicon high resolution proton transfer time of flight mass spectrometer (HR-PTRTOFMS) (shared with D. Knopf).. We have two cryogenic vacuum extraction lines for the separation and quantification of specific trace gases, such as isoprene, methanol, carbon monoxide and methane. We have developed our own preconcentration systems for the analysis of selective trace species via continuous flow isotope ratio mass spectrometry (IRMS); this allows us to quantify the isotopic composition of gases from ice core samples (e.g., Mak and Yang, 1998; Wang and Mak, 2010; Wang et al., 2010). We are currently funded to analyze the stable isotopic composition of CO from Antarctic Ice cores (e.g., SPICE), as well as Greenland ice.. We are also involved in ...

Tracer experiments are of concern to wastewater treatment engineers and researchers because of the importance of determining hydraulic regimes and retention times in wastewater treatment units. In this work, a pilot-scale maturation waste stabilisation pond (WSP) was spiked with Rhodamine WT, in order to determine how suspended organic matter would interfere with its performance as a tracer in a domestic wastewater treatment unit which had a high content of suspended algal biomass. A primary maturation pond was spiked in three separate runs with different levels of algae (high, medium and low), with a known amount of Rhodamine WT (20% v/v); the tracer was measured in the pond effluent in real time every 20 min for 3θ (the theoretical retention time, θ = 17 d). Algal biomass was monitored weekly from influent, column and effluent water samples by chlorophyll-a determination. The results show that algal biomass has a strong influence on the behaviour of Rhodamine WT as a tracer and therefore the ...

This study reports the compound specific stable carbon isotope compositions (δ13C) of lignin tetramethylammonium hydroxide (TMAH) chemolysates obtained with gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The possible sources of the errors associated are considered. Off-line (TMAH) thermochemolysis was performed on wood samples and the δ13C values of the chemolysates were compared with the bulk δ13C of the native woods and their Klason lignins. For the four woods investigated, the δ13C values, corrected for derivative carbons added, were spread over a wide range of values, ranging from −40 to −25‰ and were, on average, depleted in 13C by ca. 9‰ relative to the native woods and by ca. 7‰ relative to the Klason lignins. This large variability can be partially attributed to overlapping chromatographic peaks and to the low intensity of some of the peaks. However, isotopic fractionation cannot be ruled out, especially in compounds resulting from CC bond ...

Wendisch, V. F., Peters-Wendisch, P., de Graaf, A. A., Eikmanns, B. J., and Sahm, H. (1996). Anaplerosis in Corynebacterium glutamicum: gene inactivation studies and in vivo 13C-labeling experiments in Beijerinck Centennial, Microbiol Physiology and Gene Regulation, Scheffers, W., and van Dijken, J. eds. (Delft, Netherlands: Delft University Press), 337-338 ...

TY - JOUR. T1 - Determination of coal reactivity during coprocessing using stable isotope mass spectrometry. AU - Bottrell, S. H.. AU - Bartle, K. D.. AU - Louie, P. K K. AU - Taylor, N.. AU - Kemp, W.. AU - Steedman, W.. AU - Wallace, S.. PY - 1991/3. Y1 - 1991/3. N2 - The 13C 12C ratios of fractions with different functionality (saturates, aromatics, polar aromatics and asphaltenes) separated during mild coal-oil coprocessing runs have been determined by stable isotope ratio mass spectrometry on the CO2 produced by quantitative combustion. The proportions of coal-derived carbon in the different fractions can be determined from the difference in natural abundance of 13C between the coal and oil starting materials. The correction of the data for isotope-selective effects between different fractions (based on data from oil-only runs) is discussed. The corrected data support a complex model for the mechanism of coal dissolution, with interactions between the coal reactant and all of the fractions ...

Subjects. NMR studies were performed with eight healthy volunteers (four males and four females; aged 29 ± 6; mean ± SD) at rest after a 12 hr overnight fasting. Informed written consent was obtained from all subjects after the aims and potential risks were explained to them. The protocol was approved by the Yale University School of Medicine Human Investigation Committee.. NMR acquisition. NMR data were acquired on a 2.1 T whole body (1 m bore) magnet connected to a modified Bruker AVANCE spectrometer (Bruker Instruments, Billerica, MA). Subjects remained supine in the magnet with the head lying on top of a home-built radio-frequency NMR probe, consisting of one13C circular coil (8.5 cm diameter) and two 1H quadrature coils for1H acquisitions and decoupling. After tuning, acquisition of scout images, shimming with the FASTERMAP procedure (Shen et al., 1997), and calibration of the decoupling power,13C NMR spectra were acquired for 10 min before and during a 160 min [2-13C] acetate infusion ...

Subjects. NMR studies were performed with eight healthy volunteers (four males and four females; aged 29 ± 6; mean ± SD) at rest after a 12 hr overnight fasting. Informed written consent was obtained from all subjects after the aims and potential risks were explained to them. The protocol was approved by the Yale University School of Medicine Human Investigation Committee.. NMR acquisition. NMR data were acquired on a 2.1 T whole body (1 m bore) magnet connected to a modified Bruker AVANCE spectrometer (Bruker Instruments, Billerica, MA). Subjects remained supine in the magnet with the head lying on top of a home-built radio-frequency NMR probe, consisting of one13C circular coil (8.5 cm diameter) and two 1H quadrature coils for1H acquisitions and decoupling. After tuning, acquisition of scout images, shimming with the FASTERMAP procedure (Shen et al., 1997), and calibration of the decoupling power,13C NMR spectra were acquired for 10 min before and during a 160 min [2-13C] acetate infusion ...

Sulphuric acid is an important factor in aerosol nucleation and growth. It has been shown that ions enhance the formation of sulphuric acid aerosols, but the exact mechanism has remained undetermined. Furthermore some studies have found a deficiency in the sulphuric acid budget, suggesting a missing source. In this study the production of sulphuric acid from SO2 through a number of different pathways is investigated. The production methods are standard gas phase oxidation by OH radicals produced by ozone photolysis with UV light, liquid phase oxidation by ozone, and gas phase oxidation initiated by gamma rays. The distributions of stable sulphur isotopes in the products and substrate were measured using isotope ratio mass spectrometry. All methods produced sulphate enriched in S-34 and we find an enrichment factor (delta S-34) of 8.7 +/- 0.4 parts per thousand (1 standard deviation) for the UV-initiated OH reaction. Only UV light (Hg emission at 253.65 nm) produced a clear non-mass-dependent ...

Cenozoic climates have varied across a variety of time-scales, including slow, unidirectional change over tens of millions of years, as well as severe, geologically abrupt shifts in Earthsclimatic state. Establishing the history of atmospheric carbon dioxide is critical in prioritizing the factors responsible for past climatic events, and integral in positioning future climate change within a geological context. One approach in this pursuit uses the stable carbon isotopic composition of marine organic molecules known as alkenones. The following report represents a summary of the factors affecting alkenone carbon isotopic compositions, the underlying assumptions and accuracy of short- and long-term CO2 records established from these sedimentary molecules, and their implications for the controls on the evolution of Cenozoic climates.. ...

Pyrogenic organic matter (PyOM), the incomplete combustion product of organic materials, is considered stable in soils and represents a potentially important terrestrial sink for atmospheric carbon dioxide. One well-established method of measuring PyOM in the environment is as benzene polycarboxylic acids (BPCAs), a compound-specific method, which allows both qualitative and quantitative estimation of PyOM. Until now, stable isotope measurement of PyOM carbon involved measurement of the trimethylsilyl (TMS) or methyl (Me) polycarboxylic acid derivatives by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). However, BPCA derivatives can contain as much as 150% derivative carbon, necessitating post-analysis correction for the accurate measurement of δ13 C values, leading to increased measurement error. Here, we describe a method for δ13 C isotope ratio measurement and quantification of BPCAs from soil-derived PyOM, based on ion-exchange chromatography (IEC-IRMS). The ...

Lawrence Berkeley National Laboratory. Despite their almost incomprehensibly small size - a diameter about one ten-thousandth the thickness of a human hair - single-walled carbon nanotubes come in a plethora of different species, each with its own structure and unique combination of electronic and optical properties. Characterizing the structure and properties of an individual carbon nanotube has involved a lot of guesswork - until now.. Researchers with the U.S. Department of Energy (DOE)s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have developed a technique that can be used to identify the structure of an individual carbon nanotube and characterize its electronic and optical properties in a functional device.. Using a novel high-contrast polarization-based optical microscopy set-up, weve demonstrated video-rate imaging and in-situ spectroscopy of individual carbon nanotubes on various substrates and in functional devices, says Feng ...

Author: Sealy, Judith et al.; Genre: Journal Article; Published in Print: 2014; Title: Comparison of two methods of extracting bone collagen for stable carbon and nitrogen isotope analysis: Comparing whole bone demineralization with gelatinization and ultrafiltration

Compound-specific isotope analyses are a very promising method for reconstructing aspects of past diets, especially by combining nitrogen and carbon isotope analyses on single amino acids to clearly distinguish aquatic and terrestrial sources of proteins, and to estimate with more precision the contribution of plants in individual diets. Our application of CSIA to two Neandertals has shown that both were high trophic level consumers, with large herbivores being the main protein source. Therefore, there is no reason to invoke myriad dietary interpretations such as the consumption of mushrooms, putrid animal flesh, mammoths, or freshwater fish to explain their high bulk bone collagen nitrogen isotope values of Neandertals in relation to carnivores from the same site. However, we acknowledge that our isotopic study does not rule out the occasional consumption of these foods. Instead, the differing high N values between Neandertals and associated carnivores is likely due to the consumption of ...

Diagenetic overprint to a negative carbon isotope anomaly associated with the Gaskiers glaciation of the Ediacaran Doushantuo Formation in South ChinaDiagenetic overprint to a negative carbon isotope anomaly associated with the Gaskiers glaciation of the Ediacaran Doushantuo Formation in South China ...

Green coffee bean isotopes have been used to trace the effects of different climatic and geological characteristics associated with the Hawaii islands. Isotope ratio mass spectrometry (IRMS) and inductively coupled plasma mass spectrometry ((MC)-ICP-SFMS and ICP-QMS) were applied to determine the isotopic composition of carbon (δ13C), nitrogen (δ15N), sulfur (δ34S), and oxygen (δ18O), the isotope ...

TY - JOUR. T1 - Hepatic gluconeogenesis influences 13C enrichment in lactate in human brain tumors during metabolism of [1,2-13C]acetate. AU - Pichumani, Kumar. AU - Mashimo, Tomoyuki. AU - Vemireddy, Vamsidhara. AU - Kovacs, Zoltan. AU - Ratnakar, James. AU - Mickey, Bruce. AU - Malloy, Craig R.. AU - DeBerardinis, Ralph J.. AU - Bachoo, Robert M.. AU - Maher, Elizabeth A.. PY - 2016/7/1. Y1 - 2016/7/1. N2 - 13C-enriched compounds are readily metabolized in human malignancies. Fragments of the tumor, acquired by biopsy or surgical resection, may be acid-extracted and 13C NMR spectroscopy of metabolites such as glutamate, glutamine, 2-hydroxyglutarate, lactate and others provide a rich source of information about tumor metabolism in situ. Recently we observed 13C-13C spin-spin coupling in 13C NMR spectra of lactate in brain tumors removed from patients who were infused with [1,2-13C]acetate prior to the surgery. We found, in four patients, that infusion of 13C-enriched acetate was associated ...

The sediments that are preserved in estuarine environments (saltmarsh, riverine estuaries, mangrove habitats, lagoons, isolation basins and fjords) contain organic matter that allows investigation of the provenance of that material. These data can then be used specifically to investigate past sea level/land level changes and changes in freshwater flux. Where microfossils are poorly preserved or absent, C/N and δ13C analyses offer an alternative method to deduce environmental histories, but they are especially useful when used in conjunction with a range of other proxies, and when local modern end-member organic variables can be measured to calibrate the sedimentary C/N and δ13C. There are a wide range of C/N-δ13C based carbon studies, here we describe examples of studies in a variety of estuarine environments.. ...

Method and apparatus for providing real-time data indicative of the isotopic composition of formation fluids during drilling. The method includes the steps of: (a) providing a reference fluid having a known isotopic composition in a reference cell; (b) capturing a sample of formation; (c) providing at least one laser beam; (e) passing a beam through the reference fluid, measuring the reference-measurement beam before and after it passes through the reference fluid; (f) and passing a beam through the sample, measuring the beam before and after it passes through the sample, and calculating a first isotope concentration from those measurements. The measurements can provide information relating to the carbon isotopic composition of individual compounds in hydrocarbon gas mixtures, with the individual compounds including methane, ethane, propane, iso- or normal butane, or iso- or normal pentane.

Date: Dec 14, 2017. Author: Ryan De Vooght-Johnson. AICAR is a substance that occurs naturally in the body, but can also be used as a performance-enhancing drug in sports. Scientists from the French Anti-Doping Agency in Paris have developed an improved method for distinguishing natural AICAR from that derived from doping using GC-C-IRMS (gas chromatography, combustion, isotope ratio mass spectrometry).. Read More ...

PANGAEA - Publishing Network for Geoscientific and Environmental Data. (Appendix E) Stable carbon and oxygen isotope composition of Globigerinoides sacculifera of ODP Hole 121-758B. Occurrence Dataset https://doi.org/10.1594/pangaea.759093 accessed via GBIF.org on 2017-12-15 ...

Oecologia, 110, 120-131.. Buchmann, N., Kao, W.-Y., Ehleringer, J., (1997b) Influence of stand structure on carbon-13 of vegetation, soils and canopy air within deciduous and evergreen forests in Utah, United States. Oecologia, 110, 109-119.. Delwiche, C.C., Steyn, P.L., (1970) Nitrogen isotope fractionation in soils and microbial reactions. Environmental Science and Technology, 4(11), 929-935.. Derrien, D., Baldesdent, J., Moral, C., Santaella, C., (2003) Measurement of the 13C/12C ratio of soil-plant individual sugars by gas chromatography/combustion/isotope-ratio mass spectrometry of silylated derivatives. Rapid Communications in Mass Spectrometry, 17, 2626-2631.. Ehleringer, J.R., Field, C.B., Lin, Z.F., Kuo, C.Y., (1986) Leaf carbon isotope ratio and mineral composition in subtropical plants along an irradiance cline. Oecologia, 70, 520-526.. Feng, X., Epstein, S., (1995) Carbon isotopes from arid environments and implications for reconstructing atmospheric ...

Marine sediment slurries enriched for anaerobic, sulfate-reducing prokaryotic communities utilizing glucose and acetate were used to provide the first comparison between stable-isotope probing (SIP) of phospholipid fatty acids (PLFA) and DNA (16S rRNA and dsrA genes) biomarkers. Different 13C-labelled substrates (glucose, acetate and pyruvate) at low concentrations (100 µM) were used over a 7-day incubation to follow and identify carbon flow into different members of the community. Limited changes in total PLFA and bacterial 16S rRNA gene DGGE profiles over 7 days suggested the presence of a stable bacterial community. A broad range of PLFA were rapidly labelled (within 12 h) in the 13C-glucose slurry but this changed with time, suggesting the presence of an active glucose-utilizing population and later development of another population able to utilize glucose metabolites. The identity of the major glucose-utilizers was unclear as 13C-enriched PLFA were common (16:0, 16:1, 18:1ω7, highest ...

Native human mammary MCF-7 adenocarcinoma cells and a subline displaying resistance to 4-hydroperoxycyclophosphamide, the chemically activated form of cyclophosphamide, were grown as multicellular spheroids or on a collagen sponge matrix and perfused for study by 31P and 13C nuclear magnetic resonance spectroscopy. The natural abundance 13C spectrum of the perfused cells exhibits well-resolved resonances due to the intracellular glutathione (GSH). The resistant cell line shows a higher intensity of the GSH 13C resonances, consistent with the increased GSH concentration determined from biochemical assays of extracts. Treatment of the resistant cell line with buthionine sulfoximine selectively diminishes the intensity of the GSH resonances in the 13C nuclear magnetic resonance spectrum.. ...

The ability to switch frequently between browsing and grazing gives elephants an advantage in surviving environmental perturbations, and may help them to survive future environmental change. Previous studies of historical diet patterns of elephants yielded equivocal results. Stable carbon isotope data for Amboseli National Park, Kenya, implied an increased C4 grass intake from the early 1970s to the late 1980s [51], whereas data for Tsavo National Park, Kenya, implied a constant diet regime over 50 years [52]. Our result indicates that such disparity could arise because of the enormous variation that occurs within individuals. Long-term trends would thus be difficult to detect in the absence of continuous diet records such as those used here. Even in this instance, although the result is statistically significant (p = 0.025), the long-term trend of increasing C4 grass consumption is only weakly evident in the ivory δ13Ccollagen series (figure 2). However, the δ13Ccarbonate series depicts a ...

Tardani, D., Reich, M., Roulleau, E., Takahata, N., Sano, Y., Perez-Flores, P., Sanchez-Alfaro, P., Cembrano, J., and Arancibia, G., 2016: Geochimica Et Cosmochimica Acta, v. 184, p. 193-211.. Abstract:. There is a general agreement that fault-fracture meshes exert a primary control on fluid flow in both volcanic/magmatic and geothermal/hydrothermal systems. For example, in geothermal systems and epithermal gold deposits, optimally oriented faults and fractures play a key role in promoting fluid flow through high vertical permeability pathways. In the Southern Volcanic Zone (SVZ) of the Chilean Andes, both volcanism and hydrothermal activity are strongly controlled by the Liquine-Ofqui Fault System (LOFS), an intra-arc, strike-slip fault, and by the Arc-oblique Long-lived Basement Fault System (ALFS), a set of transpressive NW-striking faults. However, the role that principal and subsidiary fault systems exert on magma degassing, hydrothermal fluid flow and fluid compositions remains poorly ...

Understanding of the processes affecting solute transport in flowing water is important for the possibility to predict the evolution with time of polluted stream systems. This thesis presents tracer experiment methodology and model developments for solute transport in streams, with special focus on retention processes and their effect on solute stream transport. Results are presented from a tracer experiment in the Säva Stream, Uppland County, Sweden, where both a conservative (3H as tritiated water) and a reactive (51Cr as trivalent chromium ion) tracer were injected simultaneously. The time and length scales of the experiment were prolonged compared to previous studies, which allowed for new critical tests of different model concepts. It was found that the hyporheic exchange greatly affected the solute transport of both tracers. However, the retention of chromium was significantly more pronounced. About 76% of the injected chromium was lost from the stream water phase directly after the ...

This work offers a well-developed understanding of the mixing process inside Jet- Stirred Reactors (JSRs) with different geometries. Due to the difficulty of manufacturing these JSRs made in quartz, existing JSR configurations were assessed with certain modifications and optimal operating conditions were suggested for each reactor. The effect of changing the reactor volume, the nozzle diameter and shape on mixing were both studied. Two nozzle geometries were examined in this study, a crossed shape nozzle and an inclined shape nozzle. Overall, six reactor configurations were assessed by conducting tracer experiments - using the state-of-art technologies of high-speed cameras and laser absorption spectroscopy- and Computational Fluid Dynamics (CFD) simulations. The high-speed camera tracer experiment gives unique qualitative information - not present in the literature - about the actual flow field. On the other hand, when using the laser technique, a more quantitative analysis emerges with ...

What drives the accumulation of amyloid in the brains of Alzheimer patients? There are just two possibilities: overproduction of amyloid-β (Aβ) peptides, or insufficient clearance. Overproduction is at fault in inherited forms of Alzheimer disease, when mutations in the amyloid precursor protein (APP) or presenilins (PS) boost formation of amyloidogenic Aβ1-42. But in sporadic AD, even the most basic knowledge of Aβ dynamics has been lacking.. But that may soon change. For the first time, researchers have been able to measure the production and clearance of Aβ peptides in the central nervous system of human volunteers. In a clinical research tour de force, Randall Bateman, David Holtzman, and colleagues at Washington University School of Medicine in St. Louis, Missouri, used stable carbon isotope labeling and mass spectrometry analysis of Aβ from the CSF of normal human volunteers to quantify protein turnover. Surprisingly, they found that Aβ is made and degraded very rapidly in healthy ...

Various experiments involving the measurement of new, regenerated and total productivity using 15N and 13C tracers were carried out in the Bay of Bengal (BOB) and in the Arabian Sea. Results from 15N tracer experiments indicate that nitrate uptake can be underestimated by experiments with incubation time > 4 hours. Indirect evidence suggests pico- and nano-phytoplankton, on their dominance over microphytoplankton, can also influence the f-ratios. Difference in energy requirement for assimilation of different nitrogen compounds decides the preferred nitrogen source during the early hours of incubation. Variation in light intensity during incubation also plays a significant role in the assimilation of nitrogen. Results from time course experiments with both 15N and 13C tracers suggest that photoinhibition appears significant in BOB and the Arabian Sea during noon. A significant correlation has been found in the productivity values obtained using 15N and 13C tracers.. ...

Gas chromatography-isotope ratio mass spectrometry (GC-IRMS) has made it possible to analyze natural stable isotope ratios (e.g., 13C/12C, 15N/14N, 2H/1H) of individual organic contaminants in environmental samples. They may be used as fingerprints to infer contamination sources, and may demonstrate, and eve Journal of Environmental Monitoring Top Cited Papers 2009 and 2010

In South Australia and many other places, there is evidence for only two Cryogenian glaciations. The older one, known as Sturtian, occurred about 720 million years ago, and the younger, known as Marinoan, occurred about 630 million years ago. The new radiometric date from South China suggests that the Nantuo glaciation in South China must be equivalent to the Marinoan glaciation in South Australia. This is also confirmed by similar stable carbon isotopes, mineral deposits (including sedimentary barite, which is featured on the cover of the May 2004 issue of Geology), and other unusual sedimentary structures. But the exact age of the Changan and Tiesiao glacial deposits is still up in the air. There are two possibilities, Xiao says. Either they represent two pulses within a long Sturtian glaciation, or they record two discrete ice ages in South China, only one of which is recorded in South Australia by the Sturtian glacial deposit ...

Carbon dioxide from fossil fuels and deforestation carries a distinctive isotopic signature, which marks the movement of man-made CO2 through the atmosphere and carbon reservoirs (soils, biomass, and oceans). This movement of carbon, as seen in both carbon isotope data and bulk CO2 data, reveals complexity in the carbon cycle. Discrepancies between the datasets imply the active exchange of carbon between the atmosphere and carbon reservoirs. More than 85% of anthropogenic CO2 emissions, as tagged by carbon isotopes, do not remain in the atmosphere, but are absorbed by carbon reservoirs. However, some of the anthropogenic carbon in the atmosphere is exchanged for natural carbon from carbon reservoirs, so that atmospheric CO2 concentration is maintained at a level equivalent to about 44% of cumulative annual CO2 emissions over the long term. The size of carbon reservoirs is estimated at more than 7 times the volume of carbon present in the atmosphere, based on a dilution calculation of ...

Soil erosion and associated sediment transfer are among the major causes of aquatic ecosystem and surface water quality impairment. Through land use and agricultural practices, human activities modify the soil erosive risk and the catchment connectivity, becoming a key factor of sediment dynamics. Hence, restoration and management plans of water bodies can only be efficient if the sediment sources and the proportion attributable to different land uses are identified. According to this aim, we applied two approaches, namely compound-specific isotope analysis (CSIA) of long-chain fatty acids (FAs) and triterpenoid biomarker analysis, to a eutrophic lake, Lake Baldegg, and its agriculturally used catchment (Switzerland). Soils reflecting the five main land uses of the catchment (arable lands, temporary and permanent grasslands, mixed forests, orchards) were subjected to CSIA. The compound-specific stable isotope δ13C signatures clearly discriminate between potential grasslands (permanent and ...

To investigate the scale, and to determine the origin of the nitrogen isotope heterogeneity (source vs. fractionation during diamond-formation) shown for populations of mantle diamonds we have determined multiple δ13C-δ15N values and nitrogen abundances from 14 monocrystalline (MCDs) and 25 polycrystalline diamonds (PCDs) using step-wise oxidation gas sourced mass spectrometry. These data show that the heterogeneity shown for carbon and nitrogen isotope values from single diamond samples presented here is typically ,5‰ and ,8‰ respectively, both of which are comparable to the standard deviation for the mean mantle δ13C and δ15N values (±3 and ±4‰). However, there are samples that show much larger heterogeneities for δ13C and δ15N values (≤ 23‰ and ≤ 33‰ respectively), which cannot be generated by equilibrium stable isotope fractionation during, or prior to diamond-formation. These data suggest that isotopic heterogeneity may be present within the diamond-forming fluid on ...

The abundance of different isotopes in a system are usually reported as isotope ratio R or more commonly in the delta notation relative to the isotope ratio of reference material (see Chapter 2) where HA is the amount of heavy isotope in the system, LA the amount of the light isotopes, and Rstd the isotope ratio of the reference material. Since variations of isotope ratios are often small, the 5-values are usually expressed on a per mill scale by multiplication with 1000. For example a value of.... ...

books.google.comhttps://books.google.com/books/about/Radioactive_Tracer_Technique_for_Tool_We.html?id=zH8yAAAAMAAJ&utm_source=gb-gplus-shareRadioactive Tracer Technique for Tool Wear Studies ...

3H]Thymidine Incorporation Studies. Thymidine incorporation studies were performed with cells grown in 35-mm culture dishes. The cells were labeled by the addition of methyl-[3H]thymidine (1 μCi/ml) to the medium, and the reactions were stopped after 1 h. The medium was drawn off, and the cells were rinsed twice with ice-cold phosphate-buffered saline (PBS). The cultures were then fixed with ice-cold 5% trichloracetic acid overnight at 4°C, after which the cells were extracted as previously described (Guo and Reiners, 2000). A second replicate set of nonfixed dishes was treated with 0.25% trypsin-EDTA to estimate cell numbers. [3H]Thymidine was detected by scintillation counting and expressed as disintegration per minute per 103 cells.. Assessment of Apoptosis. The effects of HET0016 to induced apoptosis in 9L cells were examined by fluorescence-activated cell sorting analysis after the cells were labeled with an annexin V-fluorescein isothiocyanate (FITC) antibody (Sigma Chemical, St. Louis, ...

Stable isotope ratios of hydrogen and oxygen are widely used in hydrology, biology, chemistry, environmental sciences, food and drug authentication,

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Previous attempts to evaluate age-at-weaning from nitrogen isotope data are reviewed and shown to suffer from two faults: treating the process of weaning as an event, and estimating weaning age without accounting for the influence of growth on the bodys nitrogen isotope ratios. In particular Schurrs (J. Archaeol. Sci. 24, 919-927, 1997) mathematical model for isotopic changes during weaning, is shown to use functions appropriate only for modelling an instantaneous switch in diet whilst maintaining a constant body weight.. This paper develops an improved model which takes account of the effect of changing body mass and an extended weaning period on the trajectory of isotopic change within juveniles. The model includes typical growth patterns for human infants, and a function which represents a gradual shift from sole dependence on the mothers milk to complete weaning. These are incorporated into isotope mass balance equations, which are then solved numerically. Comparison with longitudinal ...

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