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Stable Isotope Fractionation

Stable Isotope Fractionation

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Stable isotope fractionation refers to the process by which different isotopes of an element are separated or distributed unevenly during physical, chemical, or biological processes, leading to variations in their relative abundances. This phenomenon is used in various scientific fields to trace environmental changes, metabolic pathways, and geological processes.
lightbulbAbout this topic
Stable isotope fractionation refers to the process by which different isotopes of an element are separated or distributed unevenly during physical, chemical, or biological processes, leading to variations in their relative abundances. This phenomenon is used in various scientific fields to trace environmental changes, metabolic pathways, and geological processes.

Key research themes

1. How can mass spectrometric and nuclear reaction techniques enhance precision in stable isotope analysis of trace elements and isotopes?

Precise and accurate measurement of stable isotopes at micro to ultra-trace levels is critical for advancing fields ranging from geochemistry to nuclear physics and environmental sciences. This research theme focuses on development, optimization, and validation of analytical methodologies—primarily nuclear reaction-based activation analysis and various mass spectrometry techniques including MC-ICP-MS and laser-ablation coupled mass spectrometry—to improve sensitivity, specificity, and reproducibility in stable isotope determinations, especially when sample quantities are limited or matrix complexity is high. Enhancing methodological rigor allows isotope ratios to be used more effectively as tracers in complex systems and expands the scope of isotope applications.

Microanalysis of the stable isotopes of oxygen by means of nuclear reactions
by david samuel

2021, Analytical Chemistry

Key finding: This paper pioneered the use of nuclear reactions such as 18O(p,α)15N and related reactions for the microanalysis of oxygen isotopes, enabling determination of extremely small quantities of stable oxygen isotopes with... Read more
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Determination of Precise and Accurate 5 1 V ⁄ 5 0 V Isotope Ratios by Multi-Collector ICP-MS, Part 2: Isotopic Composition of Six Reference Materials plus the Allende Chondrite and Verification Tests
by Sune Nielsen

2016

Key finding: This study developed a robust chemical separation and MC-ICP-MS protocol for precise measurements of stable vanadium isotopes across complex matrices (including meteorites), validating stability and reproducibility with a... Read more
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IsoFishR: An application for reproducible data reduction and analysis of strontium isotope ratios (87Sr/86Sr) obtained via laser-ablation MC-ICP-MS
by Justin Glessner

2023, PloS one

Key finding: The development of IsoFishR provides a standardized open-source tool for reducing and analyzing laser-ablation MC-ICP-MS data specific to 87Sr/86Sr isotopic ratios, incorporating rigorous procedures for interference... Read more
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Ion source development for the GSI on-line isotope separator
by Dieter Schardt

2021, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Key finding: This article reports the development of high-temperature and ultra-high-temperature ion sources (e.g., FEBIAD-F) optimized for online isotope separators at GSI, enabling efficient ionization and separation of exotic... Read more
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A new double spike method for the determination of mass-dependent Te isotope compositions of meteorites and terrestrial materials by MC-ICP-MS
by Barry Coles

2024, Journal of Analytical Atomic Spectrometry

Key finding: This study introduced a novel 120Te-128Te double spike MC-ICP-MS methodology coupled with optimized chemical separations for accurate and precise mass-dependent Te isotope analyses of terrestrial and meteoritic samples. The... Read more
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2. What are the causes and implications of kinetic and equilibrium isotope fractionation effects in natural and anthropogenic carbonate systems and biological contexts?

Stable isotope fractionation in carbonates and biological materials is influenced by a complex interplay of kinetic, equilibrium, and environmental factors. This theme encompasses investigations into the mechanistic origins, environmental dependencies, and applied implications of isotope fractionations—especially for oxygen, carbon, nitrogen, and sulfur isotopes—in contexts ranging from carbonate precipitation under high-pH anthropogenic conditions to isotope signals reflecting human diseases. Understanding these processes is critical for reconstructing paleoenvironments, diagnosing pathologies, and interpreting isotopic records influenced by both enzymatic and abiotic reactions.

Non-Linear Clumped Isotopes from DIC Endmember Mixing and Kinetic Isotope Fractionation in High pH Anthropogenic Tufa
by Christopher M Holdsworth

2023, Minerals

Key finding: This study demonstrated that carbonates precipitated rapidly in high pH (>10), low temperature (<20°C) anthropogenic alkaline waters record significant kinetic isotope effects, notably in ∆47 clumped isotope values, deviating... Read more
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Stable Isotope Abundance and Fractionation in Human Diseases
by Régis Hankard

2022, Metabolites

Key finding: This review synthesized evidence that metabolic deregulations in human diseases cause measurable shifts in natural stable isotope abundance (e.g., 13C, 15N, 18O) in various biological samples (tissues, hair, plasma) due to... Read more
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Multi-factorial in vivo stable isotope fractionation: causes, correlations, consequences and applications
by Roland A Werner

2015, Isotopes in environmental and health studies

Key finding: The paper provides a comprehensive framework for interpreting stable isotope fractionation in living systems, showing that in vivo fractionations on H, C, N, O, and S isotopes are governed by kinetic and thermodynamic effects... Read more
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Experimental determination of stable chlorine and bromine isotope fractionation during precipitation of salt from a saturated solution
by Magali Ader

2024, Chemical Geology

Key finding: Experimental measurements of chlorine and bromine stable isotope fractionation during salt precipitation from saturated solutions revealed variable equilibrium fractionation factors (10^3 lnα) ranging from −0.31 to +0.41,... Read more
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3. How can stable isotope applications be optimized through software standardization and uncertainty management in the measurement and calibration of isotope ratios?

Achieving reproducible, accurate stable isotope data requires standardized computational frameworks for data reduction, analysis, and uncertainty evaluation, particularly in complex or time-resolved isotopic measurements. Additionally, precise uncertainty propagation and adherence to international normalization standards underpin reliable calibration of measurements against reference materials. This theme focuses on software solutions for harmonizing isotope data workflows, best practices in reference material use, calibration curve construction, and uncertainty quantification to ensure data comparability across laboratories and improve confidence in isotopic interpretations across scientific fields.

IsoFishR: An application for reproducible data reduction and analysis of strontium isotope ratios (87Sr/86Sr) obtained via laser-ablation MC-ICP-MS
by Justin Glessner

2023, PloS one

Key finding: IsoFishR standardizes the data reduction of laser-ablation 87Sr/86Sr measurements, includes rigorous correction methods, and provides tools for noise filtration and visualization, enhancing reproducibility and comparability... Read more
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A guide for proper utilisation of stable isotope reference materials
by Wolfram Meier-Augenstein

2022, Isotopes in Environmental and Health Studies

Key finding: This guide critically examines widespread flawed practices in calibration and normalization of stable isotope δ-values, emphasizing the principle of identical treatment of samples and reference materials. It provides... Read more
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Some pitfalls in the uncertainty evaluation of isotope delta reference materials
by Manfred Gröning

2025, Accreditation and Quality Assurance

Key finding: The paper identifies common violations of the Guide to the Expression of Uncertainty in Measurement (GUM) principles in evaluating uncertainties of isotope delta reference materials, notably where combined standard... Read more
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Related Topics

  • Stable Carbon and Oxygen Isotopes
  • Stable Isotope Stratigraphy
  • Travertine and Tufa formation
  • Stable-isotope probing
  • Stable isotope hydrology
  • History of Frontiers
  • Compound Specific Stable Isotopes
  • Oxygen Isotopes

    • All papers in Stable Isotope Fractionation

    Comparison of the Quaternary travertine sites in the Denizli extensional basin based on their depositional and geochemical data
    by River Shen

    2013, Sedimentary Geology

    In the Denizli Basin (Turkey), located in the western Anatolian extensional province, travertine and tufa deposition has been an ongoing process for at least 600,000 years. Travertine bodies, which are 30 to 75 m thick and each covers... more
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    Stable isotope geochemical study of Pamukkale travertines: New evidences of low-temperature non-equilibrium calcite-water fractionation
    by Sándor Kele and 
    1 more
    István Fórizs

    2011, Sedimentary …

    Stable carbon and oxygen isotope compositions of various bedrock samples from the Denizli Basin for comparison with travertines. Table 7
    Fig. 13. Stable carbon and oxygen isotope compositions of various bedrock samples from the Denizli Basin. See Table 7 for rock types The Mg/Ca ratio of thermal water (which is increasing along the downstream sections) has an effect on the formation of aragonite (Leitmeier, 1915; Folk, 1994) and according to Fischbeck and Miiller (1971) the aragonite precipitation becomes significant when the Mg/Ca ratio is ~2.9. During the study of the Hungarian Egerszal6k travertine Kele et al. (2008a) found that aragonite-bearing samples have higher Sr abundance than aragonite-free ones, while Ishigami and Suzuki (1977) observed the same behaviour in Japanese travertines. The reason for this is that aragonite hosts more Sr relative to calcite (Gaetani and Cohen, 2006). This kind of Sr-preference cannot be observed at Pamukkale, because of the low (1-5%) aragonite concentration of travertines. At the Jandarma-section the measured Mg/Ca ratio ranges from 0.3 to 0.5, while the water temperature is below 40 °C, thus, these observations confirm the above statements. In the Denizli Basin both thermogene travertines (e.g. Pamukkale) and meteogene calcareous tufa (e.g. Giiney) occur (e.g. Filiz, 1984; Ozku et al., 2002; Horvatinti¢ et al., 2005; Ozkul et al., 2009). Based on He and C isotope analyses Giileg et al. (2002, 2005) pointed out that the high CO, pressure in the spring waters of Pamukkale derives mainly from mantle source, whereas Filiz (1984) concluded that the CO2 content of the Pamukkale Hot Springs derives from magmatic sources. Uysal et al. (2007) observed significantly positive 6'3C values (4.7 to 5.8%o) at the Pamukkale geothermal field on some fissure ridge vein travertines and suggested a thermogenic origin for the CO. According to Uysal et al. (2009) in the case of fissure ridge travertines the possible cause for the positive 5'3C values can be the non-equilibrium fractionation during quick degassing of the dissolved CO, gas (rich in !*C) during seismic strain cycles. However, our measurements showed (Fig. 13) that the recently forming terraced-slope travertine of Pamukkale has also significantly positive 5'°C values, thus, it is not necessary to assume non-equilibrium fractionation during the formation of fissure ridge travertine and consequently, 5!?C,,avertine Can be used to determine the origin of CO.
    Fig. 12. Downstream variation in the concentration of Sr, F, Mn, Ba in water samples collected along the Pamukkale Jandarma MM-section Since the EC value of thermogene waters varies normally in the 1- 10mScm7! range (Pentecost, 2005), based on its EC values (2.3- 2.4 mS cm7') the Pamukkale waters are of thermogene origin. At the Jandarma MM-section the positive correlations between the EC values, Ca, free CO2, TDS concentrations and pH values and gradual downstream decrease of dissolved Ca2* and HCO3 (and Ca/Mg ratio) (Table 2 and 4, Fig. 10) are the consequence of the continuous CO, outgassing and travertine deposition. With the progressive removal of '7CO;, the highest 8'?Cravertine Values (11-12%. PDB) were measured at the farthest point (442.5 m) from the Jandarma spring orifice. The only exception is the Pk-4 sample with 8'°C as high as 11.3%. (PDB) (Table 2), which formed on an artificial concrete dam above the travertine slope, where bacterial mats were observed and these organisms can locally remove isotopically light CO2 (Guo and Riding, 1994). At the short Beltes-2 and Karahayit, Kirmizi Su sections the downstream increase of 8) Chravertine Values was much smaller (from 5.2 to 6.6%. and from 5.1 to No close relationship can be observed between the depositional environments and geochemical composition of travertines. The presence of phosphorous in the samples collected at the lower part of the Jandarma Pk-section is connected to the plants and organic matter (Table 6). The downstream decrease of Sr, F, Mn and Ba
    Fig. 5. A) Downstream section indicating the sampling points at Karahayit, Kirmizi Su; B) Red travertine mound at Karahayit; C) Green microbial mats around the outlet of Karahayit, Kirmizi Su thermal well.
    Fig. 16. Fractionation of oxygen isotopes between calcite and water vs. the measured temperature (based on Fig. 46 of Pentecost, 2005 and Fig. 17 of Kele et al., 2008a) in the investigated temperature range (grey background). Besides the samples collected along the downstream sections of Pamukkale and Karahayit, other hot spring travertine occurrences around the world are shown together with the calculated equilibrium curve and the travertine curve presented in Kele et al. (2008a). Data of Gonfiantini et al.(1968), Friedman (1970), Turi (1986), Chafetz and Lawrence (1994), Fouke et al. (2000) and Coplen (2007) were used for comparison. Calcite-water equilibrium curve is shown based on the equation of Friedman and O'Neil (1977). Data from Grossman and Ku (1986) and Zhou and Zheng (2006).
    Fig. 4. Photo and cross-section of the Pamukkale Beltes-2-spring downstream section. A) Outlet of the Beltes-2 spring; B) Closed concrete channel conducts the water from thi Beltes-2 spring towards the terraced-slope; C) Opened channel above the major terraced slope environment of Pamukkale; D) Flow path of the water on the proximal slope of th Pamukkale, Beltes-2 section. Altitudes of the sampling points and distances between them are presented in Table 2.
    Fig. 14. Stable isotopic composition of the Pamukkale springs. GMWL = Global Meteoric Water Line (Craig, 1961), LMWL = Local Meteoric Water Line
    Fig. 1. Birds's eye view of the Pamukkale Range-front travertine indicating the downstream section of the Jandarma- and Beltes-2 springs. Earlier studies of the Denizli travertines generally focused on Pamukkale and on the hydrogeology, geothermal potential and chemistry of Pamukkale thermal waters (Gékalp, 1971; Sentiirk et al., 1971; Kogak, 1976; Canik, 1978; Ekmekci et al., 1995a,b; Gdkgéz, 1995; G6ékgéz and Filiz, 1998; Simsek et al., 2000). Filiz (1984), who first published stable isotopic data of Pamukkale Hot Springs, concluded that the CO, content of the spring waters came from magmatic resources. Altunel and Hancock (1993a, b) classified the Pamukkale travertines according to their morphology, while Altunel (1994) and Hancock and Altunel (1997) investigated the relationship between active fissuring, faulting and travertine deposition and presented some U/Th age data from the fissure ridge travertines. Cakur (1999) described the Balkayasi, Yenice, Gdlemezli and Pamukkale travertines and interpreted their structural attributes, paying particular attention to the fault zone. Ozkul et al. (2002) described different lithofacies types from recent and old travertines in the Denizli Basin, determined their local depositional environments, and presented some stable isotope data from various locations. In recent years, new geochemical and U-series dating studies
    Elemental composition of Pamukkale travertines collected downstream at the Jandarma-spring section (date of sampling: 7 November 2007). Table 6 travertine is the Pk-5 sample located at the highest point of the travertine slope showing low 513C (6.1%. PDB) and 8!80 (— 10.7%. PDB) values, whereas the last Pk-13 travertine sample, located at the end of the downstream section has the highest 6!°C (11.7%c) and 6!8O (—9.1%0) values. The shift in the 6'3C values (+ 5.6%.) is significantly higher than the downstream change in the 5!80 values (+ 1.6%) (Table 2). At the Beltes-2 section (Fig. 5) the 5'3C and 5!80O values increased downstream from 5.2 to 6.6%. and from — 11.2 to — 10.1%., the section, whereas the Pb concentration decreases downstream (Table 6).
    Fig. 3. Photo and cross-section of the Pamukkale Jandarma-spring downstream section. Sampling points, distances and elevations are also shown. There are five major thermal springs at Pamukkale above the terraced slope-travertine (360-366 m asl), namely the Ozel idare, inciralti, Beltes-1, Beltes-2, and Jandarma springs, which are located along a major, NW-SE trending fault (Fig. 2). The Cukurbag spring is located at the foot of the terraced slope on the plain. The total annual In situ measurements of some physicochemical features of thermal waters were completed at all sampling points. T, pH, Eh, and electric conductivity (EC) measurements were carried out using HACH sension 2 and HACH-LANGE HQ4OD instruments. The free COz and
    Physicochemical parameters and stable isotopic composition of thermal water samples collected from the major thermal springs of Pamukkale. The parameters were measured directly at the outlets of springs.
    Fig. 15. Stable isotopic composition of the water samples collected along the Pamukkale Pk- and MM-sections. In this paper we present oxygen isotope data from actively forming travertines and from their parent waters along downstream sections to study the physical-chemical processes governing the calcite-water oxygen isotope fractionation during travertine deposition in the 13.3 °C to 51.3 °C temperature range. In all downstream sections investigated so far, deviation from the equilibrium calcite-water fractionation was observed to be the highest around the vents and this deviation decreases with increasing distance from the spring orifice (Fig. 16), thus, the A(caicite-water) Values converge to the equilibrium curve. At the Pamukkale Jandarma spring section the A(caicite-water) values (measured apparent in Table 8, Fig. 16) intersect the equilibrium curve, showing A caicite-water) Values lower than at equilibrium conditions. However, at the Pamukkale Beltes-2 spring At the outlets of the Pamukkale springs the dissolved inorganic carbon in the thermal water at the measured pH = 6.1 is in the form of
    Physicochemical parameters and stable oxygen and hydrogen isotope composition of thermal water samples and stable carbon and oxygen isotope compositions of travertines collected along downstream sections at the Jandarma- and Beltes-2 springs of Pamukkale and at the Kirmizi Su section of Karahayit.
    Fig. 9. A) Pisolith samples (Pk-5/b) taken from the bottom of a terrace pool at the Pamukkale Jandarma section. Photomicrographs are taken from the same sample and directly fron the centre of a pisoid (B) using different enlargements. C) The centre of the pisoid consists of micritic aggregates (pelmicritic texture; dark areas), which is surrounded by branchin; sparry calcite crystals (D). E) SEM images are taken from the Pk-5/b sample showing clumps of calcite sheets and rhombohedrons, with presumably bacterial filaments (F).
    Fig. 7. Thin-section photomicrographs of travertines collected along the Pamukkale Jandarma-section showing the characteristic crystal types. A) Feather crystals of calcite show crystallographic branching. B) Alternating layers of pale sparitic clumps, divided by dark micritic laminae (Pk-4 sample). C) Branching sparite crystals of the Pk-8 sample and enlarged view of a single crystal from the same sample showing side branches perpendicular to the main crystal orientation (D). E) Feather crystals from the Pk-11 sample, which was taken from a crystalline crust sample collected on the proximal slope. F) Layers of sparitic crystals are divided by dark micritic laminae (Pk-12 sample). Layered texture of crystalline crust samples collected at the end of the proximal slope (Pk-12, G) and at the distal slope (Pk-13, H).
    Calculations of the apparent and modelled A(calcite-water) fractionations using the water temperature and 6'°O water data measured at the downstream sections of Pamukkale Karahayit (Tiirkey) and Egerszal6k (Hungary, Kele et al., 2008a) and using the equations of Friedman and O'Neil (1977) and Kim and O'Neil (1997). The A(HCO3 —water fractionations were calculated using the equation of Halas and Wolacewicz (1982). * (Based on Halas and Wolacewicz, 1982).
    Fig. 8. Pisolites at the bottom of a terrace pool (A) and microterrace pools (B) Recently forming coated bubbles (C) and paper thin rafts (D) cover the water surface around t! Cukurba§ spring. E) Pisolites are frequent deposits below the cascades of the proximal slope. F) Encrusted leaf of Nerium oleander on the distal slope.
    Fig. 6. Photographs of the major depositional subenvironments and facies occurring at Pamukkale, together with the sampling points. A) Outlet of the Jandarma-spring; B) Artificial channel system and lake (C) located above the terraced slope part of the section. D) Wood pavement and a dam separates the channel from the travertine slope. E) View of wide terrace pools covering the top of the slope. F) Cascade on the top of the proximal slope. G) and H) Proximal and distal slopes with no terrace pools at the lower part of the slope
    Fig. 10. A) Correlation between Eh and pH of water samples collected along the downstream sections of Pamukkale and Karahayit. B) Bivariation plot of Eh values and free COz content of water samples collected along the Pamukkale Jandarma MM-section. C) Bivariation plot of EC values and Ca concentration of water samples collected along the Pamukkale Jandarma MM-section. D) Downstream decrease of free CO2 content of the thermal water along the Jandarma, MM-section.
    Fig. 2. A) Simplified regional tectonic map of the eastern Mediterranean region (modified from Fig. 1 of Uysal et al., 2009). B) and C) Geological map and stratigraphy of the Denizli Basin-fill (based on Simsek, 1984; Sun, 1990; Alcicek, 2007; Alcicek et al., 2007; Alcicek, 2010).
    Mineralogical composition of the travertines collected at Pamukkale and Karahayit (date of sampling: 7 November 2007 and 7 May 2009 at Pamukkale, and 7 May 2007 at Karahayit * No travertine observed. Table 5
    Elemental composition of Pamukkale thermal water collected downstream at the Jandarma-spring (MM-section; date of sampling: 13 August 2008). Table 4
    Fig. 11. Oxygen and carbon isotopic compositions of travertine samples collected from the downstream sections of Pamukkale and Karahayit (data included in Table 2). (date o sampling: 7 November 2007 and 7 May 2009 at Pamukkale, and 7 May 2007 at Karahayit).
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    Tin isotope fingerprints of ore deposits and ancient bronze
    by Daniel Berger and 
    3 more
    Bianka Nessel
    Ernst Pernicka
    Carolin Frank

    2017, The tinworking landscape of Dartmoor in a European context - Prehistory to 20th century. Papers presented at a conference in Tavistock, Devon, 6-11 May 2016 to celebrate the 25th anniversary of the DTRG

    The sources and origin of tin, and the dispersion of bronze technology in the 3rd and 2nd millennium BC, are the central research topics of our multi-disciplinary research project, funded by an Advanced Grant of the European Research... more
    The Tinworking Landscape of Dartmoor in a European Context: Prehistory to 20th Century Figure 2 Results of experimental reduction of stannic oxide in the laboratory: Reduction with (a) carbon monoxide, (b) potassium cyanide, (c) sodium carbonate, (d) copper and (e) cupric oxide.
    The Tinworking Landscape of Dartmoor in a European Context: Prehistory to 20th Century Figure 1 Map showing major and minor tin resources in Eurasia, the region of the earliest tin bronzes and the areas of the objects analysed by our research group. 1 — Cornwall/Devon; 2 — German/Bohemian Erzgebirge; 3 — Bretagne; 4 — Iberian Peninsula; 5 — Western and Eastern Afghanistan 6 — Uzbekistan; 7 — Tadzhikistan; 8 — Kazakhstan.
    The tin isotopic analyses (TIA) were performed with a Thermo Scientific Neptune Plus MC-ICP- MS, equipped with nine Faraday Cups. Tin has ten isotopes covering a mass range of 12amu between masses 112 and 124. The measurement of the seven high mass Sn isotopes (1'°Sn, !!7Sn, ''8Sn, !!°Sn, 20Sn, 'Sn, '4Sn) was preferred, because they have the highest abundances, which helps to attain data with the highest analytical precision. This mass range also fits more closely to that of Sb (121-123) which was used for mass bias correction. Samples were run in a blank-standard-blank-sample-blank- standard bracketing setup. The calculation of the isotope ratios, the mass bias correction using the exponential law (Russell et al. 1978; Baxter et al. 2006) and 6-value calculations, were done off-line with Excel spreadsheets. The data will be given with the conventional delta notation where rrors during mass fractionation correction.
    lin Isotope Fingerprints of Ore Deposits and Ancient Bronze Briigmann et al. Figure 3a Average isotopic composition (6'°*'’Sn) of the tin metal and bronze obtained by reduction of synthetic cassiterite with five reduction methods applied in the laboratory (grey area defines the true isotopic composition of the sample).
    Figure 3b Average isotopic composition (6'°“'”Sn) of the tin metal and bronze obtained by smelting in the field with cassiterite from two different ore deposits on the Iberian Peninsula. Experiment #1 and #2 were done in crucibles, whereas experiment #3 was carried out without one. Incomplete reduction during experiment #3 caused large isotopic variation. Open symbols represent the composition of tin metal; filled symbols are the isotopic composition of the cassiterite reduced in the laboratory with the KCN reduction method. Error bars represent 2 standard deviations of the mean.
    The Tinworking Landscape of Dartmoor in a European Context: Prehistory to 20th Century Figure 4 Box-Whiskers diagram showing the variation of the 6'°“'?"Sn ratio in tin ore deposits from the Saxon-Bohemian Erzgebirge and from Cornwall and Devon in southern England as well as in EBA bronze objects belonging to the Unétice culture in Central Germany and to the Early Dynastic II and the Akkadian Periods of Mesopotamia. Yellow lines represent the median values, blue dots the averages of the isotope distributions. Data of tin ore deposits from Marahrens (unpublished); Data of Mesopotamian objects from Frank (unpublished).
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    Isotopic discrimination in the Double-crested Cormorant (Phalacrocorax auritus)
    by Elizabeth Craig and 
    1 more
    Brian Dorr
    The diet-tissue discrimination factor is the amount by which a consumer’s tissue varies isotopically from its diet, and is therefore a key element in models that use stable isotopes to estimate diet composition. In this study we measured... more
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    Factors Controlling Carbon and Hydrogen Isotope Fractionation During Biosynthesis of Lipids by Phototrophic Organisms
    by N. Pedentchouk

    2018, Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate, Handbook of Hydrocarbon and Lipid Microbiology

    The analysis of carbon and hydrogen stable isotope ratios of lipids from natural products is an integral component of research in Earth sciences. The isotopic composition of lipids from algae and higher plants can be linked with various... more
    Factors Controlling Carbon and Hydrogen Isotope Fractionation During. .. knowledge regarding individual pathways and mechanisms that affect stable isotope signatures of lipid biomarkers and their precursors is beyond the scope of this chapter. (Interested readers will be guided to key original and review publications.) Rather, the focus is on the broad picture that shows the hierarchy of controls on the isotopic composition of lipids derived from algal and higher plant sources.
    Factors Controlling Carbon and Hydrogen Isotope Fractionation During. . Alkenones, long-chain (C37—C39) polyunsaturated alkyl ketones, are by far the most commonly used algal lipids in paleoenvironmental studies. They are synthesized by only a small number of haptophyte species (Volkman et al. 1980; Marlowe et al. 1984) and are used as a proxy for sea surface temperature (Brassell et al. 1986) and paleo-pCO, levels (Pancost and Pagani 2006). They are diagenetically robust and relatively easy to prepare for GC separation and can be readily analyzed by GC- IRMS. They are one of the main targets for investigating the role of various external and internal factors controlling '*C/ "C and*H/'H compositions of algal lipids. Steroids are another group of algal lipids that have been investigated for their isotopic composition. Even though they can be diagnostic of specific taxa, e.g., dinosterol as a biomarker for dinoflagellates (Robinson et al. 1984), and are well pnreserved in the sedimentary record. thev are easily isomerized and can create
    Fig. 4 Research questions to be addressed in the future. This is not an exhaustive list of questions that need to be addressed — mainly a compilation of the key issues based on the reviewed literature. Yellow color indicates questions that refer to both algae and higher plants, brown to algae, and green to higher plants Factors Controlling Carbon and Hydrogen Isotope Fractionation During. .
    Table 1 Differences in the isotopic composition (net isotopic fractionation) of lipids relative to biomass carbon; the units are in per mil. Extracted, expanded, and redrawn from Chikaraishi (2014)
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    Sulfidic anoxia in the oceans during the Late Ordovician mass extinctions – insights from molybdenum and uranium isotopic global redox proxies
    by Emma Hammarlund

    2021, Earth-Science Reviews

    This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will... more
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    Variable Tl, Pb, and Cd concentrations and isotope compositions of enstatite and ordinary chondrites—Evidence for volatile element mobilization and decay of extinct 205 Pb
    by Barry Coles

    2017, Meteoritics &amp; Planetary Science

    100 µl H 2 O Resin cleaning 1300 µl 6 M HCl Cleaning & conversion to Clform 600 µl 0.5 M HCl Resin cleaning 300 µl 3 M HCl Resin equilibration Sample in ~500 µl 3 M HCl Sample loading 100 µl 3 M HCl Elute matrix 1500 µl 0.5 M HCl Elute... more
    Table S8. Estimated mass fractions of meteoritic Pb in the samples (finet-pp) and key paramters that constrain the estimates (a) Values without () are from the literature; see Table S7 for sources. Calculations for samples without published U, Th data are based on the mean U and Th concentrations determined for ECs and OCs in Table $7, as shown in (). (b) Pb concentration and isotope data are from this study. (c) The fret-pp Values denote the estimated fraction of meteoritic Pb in the samples, calculated as described in the text, constrained by parameters shown in this table, whereby the stated concentrations of U and Th are assumed to have uncertainties of +25% and +15% for the ECs and 35% and +20% for the OCs (see Table $7). Given these uncertainties, the estimates are assigned f,,,.:.p, = 0 if numerical results are within 4% (absolute) of 0. Solver calculations for samples marked with an * were optimized using 2°°Pb/?Pb and 2°7Pb/?™Pb only, most likely because the samples featured unusual Th/U ratios (see text).
    The mean U, Th concentrations and Th/U ratios of enstatite and ordinary chondrites were calcualted using the quoted means of individual meteorites, when several results were available.
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