Knowledge Base

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  • IRMS
  • Triple Oxygen Isotopes
  • Diatoms

A calibration of the triple oxygen isotope fractionation in the SiO2–H2O system and applications to natural samples

Z.D. Sharp (1,2), J.A. Gibbons (1), O. Maltsev (1), V. Atudorei (1,2), A. Pack (3), S. Sengupt (1,3), E.L. Shock (4,5) and L.P. Knauth (4)

1) Department of Earth and Planetary Sciences, University of New Mexico, 200 Yale Blvd, Albuquerque, NM 87131, USA, 2) Center for Stable Isotopes, University of New Mexico, 200 Yale Blvd, Albuquerque, NM 87131, USA, 3) Geowissenschaftliches Zentrum, Georg-August-Universität, Goldschmidtstraße 1, D-37073 Göttingen, Germany, 4) School of Earth and Space Exploration, Arizona State University, PO Box 871404, Tempe, AZ 85287-1404, USA, 5) School of Molecular Sciences, Arizona State University, PO Box 871404, Tempe, AZ 85287-1404, USA

Geochimica et Cosmochimica Acta (2016), V186, pp105–119, doi:10.1016/j.gca.2016.04.047

Goal: It is now recognized that variations in the Δ17O of terrestrial materials resulting from purely mass dependent fractionations, though small, have geological significance. In this study, the δ18O and δ17O values of selected low temperature quartz and silica samples were measured in order to derive the quartz-water fractionation–temperature relationship for the three oxygen isotope system. A 18O/16O quartz-water fractionation equation valid for all temperatures was generated from published high temperature exchange experiments and ...

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  • IRMS
  • Nitrogen isotopes
  • Denitrification

Multiyear dual nitrate isotope signatures suggest that N-saturated subtropical forested catchments can act as robust N sinks

Longfei Yu (1), Jing Zhu (1,2), Jan Mulder (1) and Peter Dörsch (1)

1) Department of Environmental Sciences, Norwegian University of Life Sciences, Aas, Norway, 2) Department of Environment and Resources, Guangxi Normal University, Guilin, China

Global Change Biology (2016), doi: 10.1111/gcb.13333

Goal: In forests of the humid subtropics of China, chronically elevated nitrogen (N) deposition, predominantly as ammonium (NH4+), causes significant nitrate (NO3−) leaching from well-drained acid forest soils on hill slopes (HS), whereas significant retention of NO3− occurs in near-stream environments (groundwater discharge zones, GDZ). To aid our understanding of N transformations on the catchment level, we studied spatial and temporal variabilities of concentration and natural abundance (δ15N and δ18O) of nitrate (NO3−) in soil pore water along a hydrological continuum in the N-saturated Tieshanping (TSP) catchment, southwest China. Our data show that effective removal of atmogenic NH4+ and production of NO3− in soils on HS were associated with a significant decrease in δ15N-NO3−, suggesting efficient nitrification despite low soil pH.

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  • IRMS
  • CO2
  • DOC
  • Oxygen Isotopes

An “On-Line” Method for Oxygen Isotope Exchange Between Gas-Phase CO2 and Water

N.P. Levitt (1,2) and C.S. Romanek (3)

1) NASA Astrobiology Institute and Department of Earth and Environmental Sciences, University of Kentucky, USA, 2) NASA Astrobiology Institute and Department of Geoscience, University of Wisconsin-Madison, USA, 3) NASA Astrobiology Institute and Department of Earth and Environmental Sciences, Furman University, USA

Aquatic Geochemistry (2016), V22 (3), pp 253-269, doi: 10.​1007/​s10498-016-9291-5

Goal: An “on-line” mixing system has been developed and evaluated for continuous oxygen isotope exchange between gas-phase CO2 and liquid water. The system is composed of three basic parts: equipment and materials used to introduce water and gas into a mixing reservoir, the mixing and exchange reservoir, and a vessel used to separate gas and water phases exiting the system. A series of experiments were performed to monitor the isotope exchange process over a range of temperatures (5–40 °C) and CO2 partial pressures (202–15,200 Pa).

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  • IRMS
  • NO emission

Aridity and plant uptake interact to make dryland soils hotspots for nitric oxide (NO) emissions

P.M. Homyak (1), J.C. Blankinship (1), K. Marchus (1), D.M. Lucero (2), J.O. Sickman (2) and J.P. Schimel (1)

1) Earth Research Institute and Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, 2) Department of Environmental Sciences, University of California, Riverside, CA 92521

Proceedings of the National Academy of Science in USA (2016), V113 (19), pp2608-2616, doi:10.1073/pnas.1520496113

Goal: Nitric oxide (NO) controls the atmosphere’s oxidative capacity. In soils, NO emissions are thought to be controlled by a tradeoff that develops in response to changes in soil moisture: dry soils limit substrate diffusion, whereas wet soils limit gas diffusivity, such that moist soils favor NO emissions. In drylands, however, NO emissions can be highest when soils are dry and immediately following rewetting. Aridity and vegetation interact to generate unexpected NO emission patterns. The shutdown in plant N uptake during the dry season causes NO emissions to increase, whereas arid conditions concentrate resources in dry soils, stimulating NO pulses upon rewetting. Chemistry governs the rapid initial NO pulse, whereas biological processes control later emissions as microbes recover from drought stress.

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  • IRMS
  • C isotopes
  • DOC
  • Methane cycling

Origin and temporal variability of unusually low δ13C-DOC values in two High Arctic catchments

R.S. Hindshaw (1), S.Q. Lang (2,3), S.M. Bernasconi (3), T.H.E. Heaton (4), M.R. Lindsay (5) and E.S. Boyd (5)

1) Department of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, UK; 2) Department of Earth Sciences, ETH Zürich, Zurich, Switzerland, 3) Department of Earth and Ocean Sciences, University of South Carolina, Columbia, South Carolina, USA, 4) NERC Isotope Geosciences Laboratory, Nottingham, UK, 5) Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, USA

Journal of Geophyiscal Research (2016), V121, pp1073–1085, doi:10.1002/2015JG003303.

Goal: The stable carbon isotopic composition of dissolved organic matter (δ13C-DOC) reveals information about its source and extent of biological processing. Here we report the lowest δ13C-DOC values (−43.8‰) measured to date in surface waters. The streams were located in the High Arctic, a region currently experiencing rapid changes in climate and carbon cycling. Based on the widespread occurrence of methane cycling in permafrost regions and the detection of the pmoA gene, a proxy for aerobic methanotrophs, we conclude that the low δ13C-DOC values are due to organic matter partially derived from methanotrophs consuming biologically produced, 13C-depleted methane. These findings demonstrate the significant impact that biological activity has on the stream water chemistry exported from permafrost and glaciated environments. ..., occurrences of low δ13C-DOC values may be more widespread than previously recognized, with implications for understanding C cycling in these environments.

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  • IRMS
  • Cl and Br Isotopes

Experimental determination of stable chlorine and bromine isotope fractionation during precipitation of salt from a saturated solution

H.G.M. Eggenkamp (1,2,3), M. Bonifacie (3,4), M. Ader (3) and P Agrinier (3)

1) Onderzoek & Beleving, Bussum, The Netherlands; 2) Centro de Petrologia e Geoquímica, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal, 3) Institut de Physique du Globe de Paris, Equipe Géochimie Isotopes Stables, Sorbonne Paris Cité, UMR 7154 CNRS, F-75238 Paris, France, 4) Institut de Physique du Globe de Paris, Observatoire Volcanologique et Sismologique de Guadeloupe, UMS 3454 CNRS, Le Houëlmont, 97113 Gourbeyre Guadeloupe, France

Chemical Geology (2016), V433, pp46–56, doi:10.1016/j.chemgeo.2016.04.009

Goal: In order to better understand the chlorine and bromine stable isotope fractionation that occurs when chloride and bromide salts precipitate from their saturated solutions, we determined experimentally the equilibrium fractionation factors between precipitating pure salt minerals and their coexisting saturated brine at 22 °C. Fractionation factors (expressed as 103lnα(37Cl/35Cl)salt-brine and 103lnα81Br/79Brsalt-brine) obtained for 11 chloride and 7 bromide salts of geological and industrial interest show a relatively largerange of variation (from − 0.31 to + 0.41), with the salt that precipitates having either a lower or a higher isotope ratio than the brine from which they precipitate. A negative fractionation factor indicates that the brine has a larger isotope ratio than the precipitate, a positive factor that the precipitate has a larger isotope ratio.In these measurements the uncertainty is defined as the 1σ standard deviation of replicate determinations.

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  • IRMS
  • C and O isotopes
  • Tooth enamel

Stable isotopes show resource partitioning among the early Late Miocene herbivore community at Rudabánya II: Paleoenvironmental implications for the hominoid, Rudapithecus hungaricus

L.C. Eastham (1), R.S. Feranec (2) and D.R. Begun (1)

1) Anthropology Department, University of Toronto, 19 Russell Street, Toronto, ON, M5S 2S2, Canada, 2) Research and Collections, New York State Museum, 3140 Cultural Education Center, Albany, NY 12230, United States

Palaeogeography, Palaeoclimatology, Palaeoecology (2016), V454, pp161–174, doi:10.1016/j.palaeo.2016.04.036

Goal: Examining how species use and partition resources within an environment can lead to a better understanding of community assembly and diversity. The rich early Late Miocene (early Vallesian) deposits at Rudabánya II (R. II) in northern central Hungary preserve an abundance of forest dwelling taxa, including the hominoid Rudapithecus hungaricus. Here we use the carbon and oxygen stable isotope compositions of tooth enamel carbonate from 10 genera of medium to large-bodied mammals to evaluate resource use and partitioning among the herbivore community, and to reconstruct the paleoenvironment of Rudapithecus. The range of stable carbon and oxygen isotope values (δ13C and δ18O) displayed by the R. II fauna indicates a variable forest environment, which included both open and closed canopy habitats. The relatively low δ13C and δ18O values found in all sampled taxa are consistent with high levels of precipitation and humidity.

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  • IRMS
  • Gas Bench II
  • Carbon Isotopes
  • Natural waters

Precise δ13C analysis of dissolved inorganic carbon in natural waters using automated headspace sampling and continuous-flow mass spectrometry.

M. E. Torres, A. C. Mix, and W. D. Rugh

College of Oceanic and Atmospheric Sciences, Oregon State University Corvallis, OR 97331-5503, USA

Limnology and Oceanography; Methods (2005), V3 (8), pp349–360, doi: 10.4319/lom.2005.3.349

Goal: A new method is presented for automated measurement of the δ13C of the dissolved inorganic carbon in natural waters, using a Gas Bench-II online with a DELTA XL IRMS. This technique requires a volume (30-500 mL), analyses are rapid (~80 samples/d), and little / no manual preparation is necessary. The flexibility offered by using sample loops of various sizes permits analyses of aliquots containing 2 to 50 μg C. Based on multiple replicate measurements over a 7-week period, the precision of this technique is estimated to be better than ± 0.15‰ (1 sample std. dev.), which is similar to the precision of methods in use. This precision can be improved upon (averaging ± 0.04‰, but generally better than ± 0.07‰) and analyses are monitored against a stock solution of reagent NaHCO3, which remains isotopically stable in powder form. NaHCO3 can be analyzed with traditional acid-digestion methods using dual-inlet mass spectrometry, as well as in dissolved form on the Gas Bench-II.

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  • IRMS
  • O isotopes
  • Life on Mars

Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars

R. Shaheen, A. Abramian, J. Horn, G. Dominguez, R. Sullivan, and Mark H. Thiemens

Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093

Proceedings of the National Academy of Science in USA (2010), V107 (47), pp20213–20218, doi: 10.1073/pnas.1014399107

Goal: Shorted text: The life on Mars debate centers around the source of the globular, micrometer-sized mineral ALH84001 meteorite carbonates; consequently, ident. of Martian processes to form carbonates is critical. A earth and likely martian carbonate formation process is reported (terrestrial aerosol carbonates; 17O excess; 0.4–3.9‰). The unique O-isotopic composition describes the atmos. heterog. chem. reaction on aerosol surfaces. Lab exp. define the transfer of O3 isotopic anomaly to carbonates via H2O2 formation (O3 reacts with surface adsorbed water). This chem. react. scenario provides an explanation for the isotopically anomalous carbonates production. The anomalous H2O2 formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir (producing MIF secondary mineral evaporites). The formation of H2O2 via heterogeneous chemistry on aerosol surfaces reveals an oxidative process in understanding ozone and oxygen chemistry (Mars & Earth).

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  • Delta V Advantage
  • 13C and 18 O
  • Tooth enamel

The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets

A. Zazzo (1), M. Balasse (1), B.H. Passey (2), A.P. Moloney (3), F.J. Monahan (4) and O. Schmidt (5)

1) Muséum national d’Histoire naturelle, Département Ecologie et Gestion de la Biodiversité, USM 303/UMR 7209 du CNRS, “Archéozoologie, Archéobotanique: Sociétés, Pratiques et Environnements”, case postale 56, 55 rue Buffon, F-75231 Paris cedex 05, France, 2) Department of Earth and Planetary Sciences, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA, 3) Teagasc, Grange Beef Research Centre, Dunsany, Co. Meath, Ireland, 4) UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland, 5) UCD School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland

Geochimica et Cosmochimica Acta (2010), V74 (12), pp3571–3586, doi:10.1016/j.gca.2010.03.017

Goal: Shorted text: Quantitative reconstruction of paleodiet carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite (εD–E), as well as timing and duration of the mineralization process. High resolution sampling and stable carbon isotope analysis of breath CO2 following a diet-switch showed that 70–90% of dietary carbon had turned over in < 24 h.The changes in diet were recorded in all molars. Portions of enamel in equilibrium with dietary carbon were used to calculate εD–E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. Our results demonstrate that they can provide useful information about dietary variability if the mineralization process is taken into account.

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  • IRMS
  • Gas Bench II
  • Calibration method for D and O isotopes
  • Water

A simple, practical methodology for routine VSMOW/SLAP normalization of water samples analyzed by continuous flow methods

Steve Nelson

Dept. of Geology, Brigham Young University, Provo, Utah 84602, USA.

Rapid Communications in Mass Spectrometry (2000), V14 (12), pp1044-6, doi:10.1002/1097-0231(20000630)

Goal: Normalization of stable isotope data is important for meaningful inter-laboratory comparisons of data, especially for waters. As a result, large, systematic errors may arise in continuous flow applications without correction, whereas normalization to the VSMOW/SLAP scale can facilitate inter-laboratory comparison and can be accomplished by a simple procedure. Delta values for these standards, as analyzed, are plotted against the calibrated values and a linear regression is performed. The resulting equation is applied to unknown samples to achieve the normalization. The one-sigma [1sigma] standard deviation for replicate samples by this normalization method using a Gas Benchll should be

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  • IRMS
  • Gas Bench II
  • 18O-isotope equilibration
  • CO2 in sparkling beverages

Gas Bench/isotope ratio mass spectrometry: a carbon isotope approach to detect exogenous CO2 in sparkling drinks

Ana I. Cabañero, Tamar San-Hipólito and Mercedes Rupérez

Laboratorio Arbitral Agroalimentario. Ministerio de Agricultura, Pesca y Alimentación, Crta. Coruña Km 10.700, 28023 Madrid. Spain

Rapid Communications in Mass Spectrometry (2007), V21, pp3323–3328, doi: 10.1002/rcm.3212

Goal: A new procedure for the determination of carbon dioxide (CO2) 13C/12C isotope ratios, using direct injection into a Gas Bench/isotope ratio mass spectrometry system, has been developed to improve isotopic methods devoted to the study of the authenticity of sparkling drinks. It has been demonstrated that the addition of C4 sugar to semi-sparkling wine (aguja) and industrial CO2 addition to sparkling wine (cava) or water can be detected. The new procedure has advantages over existing methods in terms of analysis time and sample treatment. In addition, it is the first isotopic method developed that allows 13C/12C determination directly from a liquid sample without previous CO2 extraction. No significant isotopic fractionation was observed nor any influence by secondary compounds present in the liquid phase.

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  • IRMS
  • Gas Bench II
  • Hydrogen Isotopes
  • Fruit Juice and Wine

Automated H2/H2O Equilibration for δD Determination on Aqueous Samples Using Thermo Scientific Gas Bench II

Alexander Duhr, Andreas Hilkert

Thermo Fisher Scientific, Bremen, Germany

AN30049

Goal: The measurement of the D/H ratio of water is one of the most important pplications of isotope ratio massspectrometers. Very diverse applications, ranging from studies of variations in natural abundance in the hydrologic cycle to authenticity control of beverages or the use of D-enriched tracers in human and animal metabolic studies, demand a general analytical solution, which provides high precision/ high accuracy/high throughput analysis of D/H in an enormous range of aqueous substrates. With the Gas Bench II, water samples > 200 μL can be routinely analyzed with a precision and accuracy < 1 ‰.

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  • IRMS
  • Gas Bench II
  • 18O-Equilibration
  • Water, Fruit Juice and Wine

18O-Equilibration on Water, Fruit Juice and Wine

Andreas Hilkert, Hairigh Avak,

Thermo Fisher Scientific, Bremen, Germany

AN30048

Goal: The measurement of the 18O/16O ratio of water is one of the most important applications of isotope ratio mass spectrometry. The measurement of the 18O/16O ratio of water is one of the most important applications of isotope ratio mass spectrometry.In CO2-water equilibration, a small amount of CO2 in the headspace of a sample vial is isotopically equilibrated with the water entrained in a liquid sample. The very small amount of CO2 in the headspace ensures complete transfer of the 18O information during equilibration (CO2/H2O < 1:3000). With the Gas Bench II, water samples < 200 μl or less can be routinely analyzed to a precision and accuracy of < 0.06 ‰.

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  • IRMS
  • Gas Bench II
  • δ18O and δ13C
  • Carbonate materials
  • Small samples sizes

δ18O and δ13C Determination of Carbonates

Alexander Duhr, Andreas Hilkert

Thermo Fisher Scientific, Bremen, Germany

AN30050

Goal: The Thermo Scientific Gas Bench II with the Carbonate-Option, an autosampler assisted sample preparation and loop injection interface, offers a fast and flexible alternative using modern continuous flow technology coupling to the ThermoScientific isotope ratio mass spectrometers DELTA V Advantage, DELTA V Plus and 253 Plus. The Gas Bench II in carbonate mode uses the principle of individual acid baths. Laboratories have shown that at least 80 samples per day (including 14 standards for quality control) can be processed in routine operation. An overall precision of 0.08 ‰ for δ18O and of 0.06 ‰ for δ13C or better has been achieved and accurate measurements of samples containing in excess of 100 μg of carbonate.