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Journal articles on the topic 'Ca isotopic measurements'

Author: Grafiati

Published: 6 September 2023

Last updated: 31 July 2025

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1

Hillaire-Marcel, Claude, та Christiane Causse. "The Late Pleistocene Laurentide Glacier: Th/U Dating of its Major Fluctuations and δ18O Range of the Ice". Quaternary Research 32, № 2 (1989): 125–38. http://dx.doi.org/10.1016/0033-5894(89)90070-7.

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AbstractDirect information on the isotopic composition and timing of the now-vanished Laurentide glacier can be found in subglacial calcite or in early diagenetic concretions from glaciolacustrine deposits. Th/U isotopic measurements on early diagenetic concretions frome Lake Deschaillons varves (St. Lawrence Lowland, Québec) date the early Wisconsinan major ice advance at ca. 80,000 yr (isotopic stage 5a/4 transition). Significant retreat occurred at ca. 46,000 yr (isotopic stage 3) as indicated by Th/U isochrones on early diagenetic concretions from Lake Gayhurst varves in the Appalachian fo

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Herbert, Timothy D., Rocio Caballero-Gill, and Joseph B. Novak. "A revised mid-Pliocene composite section centered on the M2 glacial event for ODP Site 846." Climate of the Past 17, no. 3 (2021): 1385–94. http://dx.doi.org/10.5194/cp-17-1385-2021.

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Abstract. The composite section from ODP Site 846 has provided key data sets for Pliocene stable isotope and paleoclimatic time series. We document here apparent outliers in previously published data sets for stable isotopes and alkenone-derived sea surface temperature (SST) estimates in the Pliocene interval containing the M2 glaciation (ca. 3.290–3.3 Ma) by tying high-resolution core measurements to a continuous downhole conductivity log. We generate a revised sequence of new stable isotopic and alkenone measurements across the M2 event that correlate well to the revised splices of color ref

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Mennekes, David, Michael Rinderer, Stefan Seeger, and Natalie Orlowski. "Ecohydrological travel times derived from in situ stable water isotope measurements in trees during a semi-controlled pot experiment." Hydrology and Earth System Sciences 25, no. 8 (2021): 4513–30. http://dx.doi.org/10.5194/hess-25-4513-2021.

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Abstract. Tree water uptake processes and ecohydrological travel times have gained more attention in recent ecohydrological studies. In situ measurement techniques for stable water isotopes offer great potential to investigate these processes but have not been applied much to tree xylem and soils so far. Here, we used in situ probes for stable water isotope measurements to monitor the isotopic signatures of soil and tree xylem water before and after two deuterium-labeled irrigation experiments. To show the potential of the method, we tested our measurement approach with 20-year-old trees of th

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Alvarez Caraveo, Blanca, Maxence Guillermic, Alan Downey-Wall та ін. "Magnesium (Mg∕Ca, δ²⁶Mg), boron (B∕Ca, δ¹¹B), and calcium (Ca²⁺) geochemistry of Arctica islandica and Crassostrea virginica extrapallial fluid and shell under ocean acidification". Biogeosciences 22, № 12 (2025): 2831–51. https://doi.org/10.5194/bg-22-2831-2025.

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Abstract. The geochemistry of biogenic carbonates has long been used as proxies to record changing seawater parameters. However, the effect of ocean acidification (OA) on seawater chemistry and organism physiology could impact isotopic signatures and how elements are incorporated into the shell. In this study, we investigated the geochemistry of three reservoirs important for biomineralization – seawater, the extrapallial fluid (EPF), and the shell – in two bivalve species: Crassostrea virginica and Arctica islandica. Additionally, we examined the effects of three ocean acidification condition

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Keller, Kathrin M., Sebastian Lienert, Anil Bozbiyik, et al. "20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models." Biogeosciences 14, no. 10 (2017): 2641–73. http://dx.doi.org/10.5194/bg-14-2641-2017.

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Abstract. Measurements of the stable carbon isotope ratio (δ13C) on annual tree rings offer new opportunities to evaluate mechanisms of variations in photosynthesis and stomatal conductance under changing CO2 and climate conditions, especially in conjunction with process-based biogeochemical model simulations. The isotopic discrimination is indicative of the ratio between the CO2 partial pressure in the intercellular cavities and the atmosphere (ci∕ca) and of the ratio of assimilation to stomatal conductance, termed intrinsic water-use efficiency (iWUE). We performed isotope-enabled simulation

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Leavitt, Steven W., та Robert M. Kalin. "A New Tree-Ring Width, δ13C and 14C Investigation of the Two Creeks Site". Radiocarbon 34, № 3 (1992): 792–97. http://dx.doi.org/10.1017/s0033822200064092.

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We have made isotopic and dendrochronologic measurements on material collected from the Two Creeks site. Radiocarbon dating of outside wood of four logs yielded an average age of 11,760 ± 100 BP, in good agreement with results of Broecker and Farrand (1963) over 25 years ago. The range of 11,640 ± 160 to 11,900 ± 160 BP suggests a period of forest growth of 200–300 years, consistent with a ring-width chronology established by Kaiser (1987). Ring counting of five specimens gave a range of individual tree ages from 110 to 182 years, and width measurements indicate very low year-to-year variation

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Dickinson, Dane, Samuel Bodé та Pascal Boeckx. "System for <i>δ</i><sup>13</sup>C–CO<sub>2</sub> and <i>x</i>CO<sub>2</sub> analysis of discrete gas samples by cavity ring-down spectroscopy". Atmospheric Measurement Techniques 10, № 11 (2017): 4507–19. http://dx.doi.org/10.5194/amt-10-4507-2017.

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Abstract. A method was devised for analysing small discrete gas samples (50 mL syringe) by cavity ring-down spectroscopy (CRDS). Measurements were accomplished by inletting 50 mL syringed samples into an isotopic-CO2 CRDS analyser (Picarro G2131-i) between baseline readings of a reference air standard, which produced sharp peaks in the CRDS data feed. A custom software script was developed to manage the measurement process and aggregate sample data in real time. The method was successfully tested with CO2 mole fractions (xCO2) ranging from < 0.1 to > 20 000 ppm and δ13C–CO2 values from −

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Bownes, Jessica M., Philippa L. Ascough, Gordon T. Cook, Iona Murray, and Clive Bonsall. "Using Stable Isotopes and a Bayesian Mixing Model (FRUITS) to Investigate Diet at the Early Neolithic Site of Carding Mill Bay, Scotland." Radiocarbon 59, no. 5 (2017): 1275–94. http://dx.doi.org/10.1017/rdc.2017.39.

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AbstractWe present δ13C, δ15N, and δ34S measurements on archaeological human and animal bone collagen samples from a shell midden dating to the Neolithic ca. 4000–3500 cal BC, together with measurements on modern fish and shellfish. These data were used in conjunction with the Bayesian mixing model, Food Reconstruction Using Isotopic Transferred Signals (FRUITS), to reconstruct human diet at the site. We demonstrate the importance of using a geographically appropriate faunal baseline in stable isotope paleodietary studies, and suggest that Neolithic individuals at this site consumed up to ca.

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Sangster, D. F., P. M. Outridge, and W. J. Davis. "Stable lead isotope characteristics of lead ore deposits of environmental significance." Environmental Reviews 8, no. 2 (2000): 115–47. http://dx.doi.org/10.1139/a00-008.

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Stable Pb isotopes are increasingly used in environmental science as tracers of natural and anthropogenic Pb sources. This review provides a summary of the recent geological literature concerning Pb isotopes in global Pb ore deposits. The isotopic characteristics of 151 Pb deposits, including 78 20th-century producing mines, have been summarized using the 204Pb-based ratios common to geological science and the 206Pb- and 207Pb-based ratios (i.e., excluding 204Pb) more often employed in environmental studies. A number of current mines, including those exploiting several Australian, Scandinavian

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10

Liu, Yi, Chaoyu Zhang, Jiyi Jiang, et al. "Interaction between Groundwater and Surface Water in the Qujiang River Basin in China: Evidence from Chemical Isotope Measurements." Water 15, no. 22 (2023): 3932. http://dx.doi.org/10.3390/w15223932.

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The Qujiang River Basin is a significant water system located in Zhejiang Province, China, that serves as a primary water source for Quzhou City. For this research, we collected and examined water samples from the Qujiang River Basin. In this study, we collected and analyzed water samples from the Qujiang River Basin and employed a combination of methods, including water balance analysis; Piper trilinear diagram; Gibbs diagram; and environmental tracer techniques, such as hydrochemical and isotopic analysis. These techniques helped us to analyze the spatial distribution patterns and evolutiona

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Rodgers, P., C. Soulsby, S. Waldron, and D. Tetzlaff. "Using stable isotope tracers to assess hydrological flow paths, residence times and landscape influences in a nested mesoscale catchment." Hydrology and Earth System Sciences 9, no. 3 (2005): 139–55. http://dx.doi.org/10.5194/hess-9-139-2005.

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Abstract. δ18O measurements in precipitation and stream waters were used to investigate hydrological flow paths and residence times at nested spatial scales in the mesoscale (233 km2) River Feugh catchment in the northeast of Scotland over the 2001-2002 hydrological year. Precipitation δ18O exhibited strong seasonal variation, which although significantly damped within the catchment, was reflected in stream water at six sampling sites. This allowed δ18O variations to be used to infer the relative influence of soil-derived storm flows with a seasonally variable isotopic signature, and groundwat

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Carignan, Jean, Damien Cardinal, Anton Eisenhauer, et al. "A Reflection on Mg, Cd, Ca, Li and Si Isotopic Measurements and Related Reference Materials." Geostandards and Geoanalytical Research 28, no. 1 (2004): 139–48. http://dx.doi.org/10.1111/j.1751-908x.2004.tb01050.x.

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Hattori, S., S. O. Danielache, M. S. Johnson, et al. "Ultraviolet absorption cross sections of carbonyl sulfide isotopologues OC<sup>32</sup>S, OC<sup>33</sup>S, OC<sup>34</sup>S and O<sup>13</sup>CS: isotopic fractionation in photolysis and atmospheric implications." Atmospheric Chemistry and Physics Discussions 11, no. 7 (2011): 20487–520. http://dx.doi.org/10.5194/acpd-11-20487-2011.

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Abstract. We report measurements of the ultraviolet absorption cross sections of OC32S, OC33S, OC34S and O13CS from 195 to 260 nm. The OCS isotopologues were synthesized from isotopically-enriched elemental sulfur by reaction with carbon monoxide. The measured cross section of OC32S is consistent with literature spectra recorded using natural abundance samples. Relative to the spectrum of the most abundant isotopologue, substitution of heavier rare isotopes has two effects. First, as predicted by the reflection principle, the Gaussian-based absorption envelope becomes slightly more narrow and

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Hattori, S., S. O. Danielache, M. S. Johnson, et al. "Ultraviolet absorption cross sections of carbonyl sulfide isotopologues OC<sup>32</sup>S, OC<sup>33</sup>S, OC<sup>34</sup>S and O<sup>13</sup>CS: isotopic fractionation in photolysis and atmospheric implications." Atmospheric Chemistry and Physics 11, no. 19 (2011): 10293–303. http://dx.doi.org/10.5194/acp-11-10293-2011.

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Abstract. We report measurements of the ultraviolet absorption cross sections of OC32S, OC33S, OC34S and O13CS from 195 to 260 nm. The OCS isotopologues were synthesized from isotopically-enriched elemental sulfur by reaction with carbon monoxide. The measured cross section of OC32S is consistent with literature spectra recorded using natural abundance samples. Relative to the spectrum of the most abundant isotopologue, substitution of heavier rare isotopes has two effects. First, as predicted by the reflection principle, the Gaussian-based absorption envelope becomes slightly narrower and blu

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15

Weber, Felix, Christoph Emanuel Düllmann, Vadim Gadelshin, et al. "Probing the Atomic Structure of Californium by Resonance Ionization Spectroscopy." Atoms 10, no. 2 (2022): 51. http://dx.doi.org/10.3390/atoms10020051.

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The atomic structure of californium is probed by two-step resonance ionization spectroscopy. Using samples with a total amount of about 2×1010 Cf atoms (ca. 8.3 pg), ground-state transitions as well as transitions to high-lying Rydberg states and auto-ionizing states above the ionization potential are investigated and the lifetimes of various atomic levels are measured. These investigations lead to the identification of efficient ionization schemes, important for trace analysis and nuclear structure investigations. Most of the measurements are conducted on 250Cf. In addition, the isotope shift

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Nava-Fernandez, Cinthya, Adam Hartland, Fernando Gázquez, et al. "Pacific climate reflected in Waipuna Cave drip water hydrochemistry." Hydrology and Earth System Sciences 24, no. 6 (2020): 3361–80. http://dx.doi.org/10.5194/hess-24-3361-2020.

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Abstract. Cave microclimate and geochemical monitoring is vitally important for correct interpretations of proxy time series from speleothems with regard to past climatic and environmental dynamics. We present results of a comprehensive cave-monitoring programme in Waipuna Cave in the North Island of New Zealand, a region that is strongly influenced by the Southern Westerlies and the El Niño–Southern Oscillation (ENSO). This study aims to characterise the response of the Waipuna Cave hydrological system to atmospheric circulation dynamics in the southwestern Pacific region in order to assure t

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Gupta, Sebanti, John M. Louis, and Robert Tycko. "Effects of an HIV-1 maturation inhibitor on the structure and dynamics of CA-SP1 junction helices in virus-like particles." Proceedings of the National Academy of Sciences 117, no. 19 (2020): 10286–93. http://dx.doi.org/10.1073/pnas.1917755117.

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HIV-1 maturation involves conversion of the immature Gag polyprotein lattice, which lines the inner surface of the viral membrane, to the mature capsid protein (CA) lattice, which encloses the viral RNA. Maturation inhibitors such as bevirimat (BVM) bind within six-helix bundles, formed by a segment that spans the junction between the CA and spacer peptide 1 (SP1) subunits of Gag, and interfere with cleavage between CA and SP1 catalyzed by the HIV-1 protease (PR). We report solid-state NMR (ssNMR) measurements on spherical virus-like particles (VLPs), facilitated by segmental isotopic labeling

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Retzmann, Anika, Dorothy Walls, Kerri Miller, Michael Wieser, Johanna Irrgeher, and Thomas Prohaska. "Assessing the potential of online ICP–MS analysis to optimize Ca/matrix separation using DGA Resin for subsequent isotopic analysis." Monatshefte für Chemie - Chemical Monthly 152, no. 4 (2021): 401–10. http://dx.doi.org/10.1007/s00706-021-02754-2.

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AbstractCa isotopes have gained increasing interest as a diagnostic tool for bone diseases due to the variations in abundances as a consequence of changes in bone-mineral balance. Optimized Ca/matrix separation prior to analysis is a prerequisite for reliable isotope ratio measurements in complex biological matrices such as blood, serum, or urine. The online analysis of analyte/matrix separation by ICP-MS enables direct assessment of elution profiles supporting the optimization process. The integration of transient signals and signal suppression challenge the quantification and interpretation

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Schleinkofer, Nicolai, David Evans, Max Wisshak, et al. "Host-influenced geochemical signature in the parasitic foraminifera <i>Hyrrokkin sarcophaga</i>." Biogeosciences 18, no. 16 (2021): 4733–53. http://dx.doi.org/10.5194/bg-18-4733-2021.

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Abstract. Hyrrokkin sarcophaga is a parasitic foraminifera that is commonly found in cold-water coral reefs where it infests the file clam Acesta excavata and the scleractinian coral Desmophyllum pertusum (formerly known as Lophelia pertusa). Here, we present measurements of the trace element and isotopic composition of these parasitic foraminifera, analyzed by inductively coupled optical emission spectrometry (ICP-OES), electron probe microanalysis (EPMA) and mass spectrometry (gas-source MS and inductively-coupled-plasma MS). Our results reveal that the geochemical signature of H. sarcophaga

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Benaafi, Mohammed, and Abdulaziz Al-Shaibani. "Hydrochemical and Isotopic Investigation of the Groundwater from Wajid Aquifer in Wadi Al-Dawasir, Southern Saudi Arabia." Water 13, no. 13 (2021): 1855. http://dx.doi.org/10.3390/w13131855.

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The Wajid aquifer is considered the main source of water for drinking and irrigation in Wadi Al-Dawasir and Najran, the southern region of Saudi Arabia. This aquifer has been used since the 1960s, and due to the expansion in agricultural activities, the aquifer has been overexploited. The study aims to understand the origin, hydrochemical processes of the groundwater in the shallow unconfined, deep unconfined, and confined parts of the Wajid aquifer in the Wadi Al-Dawasir area. In-situ hydrochemical parameters (pH, temperature, EC, and TDS) were measured in the field, and groundwater samples w

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Biriukov, Denys, Hsiu-Wen Wang, Nikhil Rampal, et al. "The “good,” the “bad,” and the “hidden” in neutron scattering and molecular dynamics of ionic aqueous solutions." Journal of Chemical Physics 156, no. 19 (2022): 194505. http://dx.doi.org/10.1063/5.0093643.

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We characterize a concentrated 7.3 m CaCl2 solution, combining neutron diffraction with chloride isotopic substitution (Cl-NDIS) in null water and molecular dynamics (MD) simulations. We elucidate the solution structure, thermodynamic properties, and extent of ion pairing previously suggested as concentration-dependent and often not observed at lower concentrations. Our Cl-NDIS measurements designate the solvent-shared ion pairing as dominant and the contact ion pairing (CIP) as insignificant even under conditions close to the solubility limit. The MD models parameterized against neutron diffr

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McCulloch, Malcolm, Mike Cappo, James Aumend, and Wolfgang Müller. "Tracing the life history of individual barramundi using laser ablation MC-ICP-MS Sr-isotopic and Sr/Ba ratios in otoliths." Marine and Freshwater Research 56, no. 5 (2005): 637. http://dx.doi.org/10.1071/mf04184.

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Otoliths preserve a continuous geochemical record of its life history, from the earliest natal stage through to adulthood. Using in situ laser ablation (UV) multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) measurements of Sr isotopic compositions together with elemental abundances (Ca, Sr, Ba and Mg), we show how it is possible to characterise the various types of habitats encountered throughout the lifecycle history of individual barramundi. Unlike trace element concentrations, which can be modulated by physiological processes, Sr isotopic compositions of otoliths prov

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Leavitt, Steven, Li Cheng, David Williams, et al. "Soil Organic Carbon Isotope Tracing in Sorghum under Ambient CO2 and Free-Air CO2 Enrichment (FACE)." Land 11, no. 2 (2022): 309. http://dx.doi.org/10.3390/land11020309.

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As atmospheric carbon dioxide concentrations, [CO2Air], continue their uncontrolled rise, the capacity of soils to accumulate or retain carbon is uncertain. Free-air CO2 enrichment (FACE) experiments have been conducted to better understand the plant, soil and ecosystem response to elevated [CO2], frequently employing commercial CO2 that imparts a distinct isotopic signal to the system for tracing carbon. We conducted a FACE experiment in 1998 and 1999, whereby sorghum (C4 photosynthetic pathway) was grown in four replicates of four treatments using a split-strip plot design: (i) ambient CO2/a

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Howes, Ella L., Karina Kaczmarek, Markus Raitzsch, et al. "Decoupled carbonate chemistry controls on the incorporation of boron into <i>Orbulina universa</i>." Biogeosciences 14, no. 2 (2017): 415–30. http://dx.doi.org/10.5194/bg-14-415-2017.

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Abstract. In order to fully constrain paleo-carbonate systems, proxies for two out of seven parameters, plus temperature and salinity, are required. The boron isotopic composition (δ11B) of planktonic foraminifera shells is a powerful tool for reconstructing changes in past surface ocean pH. As B(OH)4− is substituted into the biogenic calcite lattice in place of CO32−, and both borate and carbonate ions are more abundant at higher pH, it was suggested early on that B ∕ Ca ratios in biogenic calcite may serve as a proxy for [CO32−]. Although several recent studies have shown that a direct conne

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Godbillot, Camille, Fabrice Minoletti, Franck Bassinot, and Michaël Hermoso. "Parallel between the isotopic composition of coccolith calcite and carbon levels across Termination II: developing a new paleo-CO<sub>2</sub> probe." Climate of the Past 18, no. 3 (2022): 449–64. http://dx.doi.org/10.5194/cp-18-449-2022.

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Abstract. Beyond the pCO2 records provided by ice core measurements, the quantification of atmospheric CO2 concentrations and changes thereof relies on proxy data, the development of which represents a foremost challenge in paleoceanography. In the paleoceanographic toolbox, the coccolithophores occupy a notable place, as the magnitude of the carbon isotopic fractionation between ambient CO2 and a type of organic compounds that these photosynthetic microalgae synthesize (the alkenones) represents a relatively robust proxy to reconstruct past atmospheric CO2 concentrations during the Cenozoic.

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Vardag, S. N., C. Gerbig, G. Janssens-Maenhout та I. Levin. "Estimation of continuous anthropogenic CO<sub>2</sub>: model-based evaluation of CO<sub>2</sub>, CO, δ<sup>13</sup>C(CO<sub>2</sub>) and Δ<sup>14</sup>C(CO<sub>2</sub>) tracer methods". Atmospheric Chemistry and Physics 15, № 22 (2015): 12705–29. http://dx.doi.org/10.5194/acp-15-12705-2015.

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Abstract. We investigate different methods for estimating anthropogenic CO2 using modeled continuous atmospheric concentrations of CO2 alone, as well as CO2 in combination with the surrogate tracers CO, δ13C(CO2) and Δ14C(CO2). These methods are applied at three hypothetical stations representing rural, urban and polluted conditions. We find that, independent of the tracer used, an observation-based estimate of continuous anthropogenic CO2 is not yet feasible at rural measurement sites due to the low signal-to-noise ratio of anthropogenic CO2 estimates at such settings. The tracers δ13C(CO2) a

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Fantle, Matthew S., Heather Tollerud, Anton Eisenhauer, and Chris Holmden. "The Ca isotopic composition of dust-producing regions: Measurements of surface sediments in the Black Rock Desert, Nevada." Geochimica et Cosmochimica Acta 87 (June 2012): 178–93. http://dx.doi.org/10.1016/j.gca.2012.03.037.

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Jones, Sam P., Jérôme Ogée, Joana Sauze, et al. "Non-destructive estimates of soil carbonic anhydrase activity and associated soil water oxygen isotope composition." Hydrology and Earth System Sciences 21, no. 12 (2017): 6363–77. http://dx.doi.org/10.5194/hess-21-6363-2017.

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Abstract. The contribution of photosynthesis and soil respiration to net land–atmosphere carbon dioxide (CO2) exchange can be estimated based on the differential influence of leaves and soils on budgets of the oxygen isotope composition (δ18O) of atmospheric CO2. To do so, the activity of carbonic anhydrases (CAs), a group of enzymes that catalyse the hydration of CO2 in soils and plants, needs to be understood. Measurements of soil CA activity typically involve the inversion of models describing the δ18O of CO2 fluxes to solve for the apparent, potentially catalysed, rate of CO2 hydration. Th

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Rodgers, P., C. Soulsby, S. Waldron, and D. Tetzlaff. "Using stable isotope tracers to identify hydrological flow paths, residence times and landscape controls in a mesoscale catchment." Hydrology and Earth System Sciences Discussions 2, no. 1 (2005): 1–35. http://dx.doi.org/10.5194/hessd-2-1-2005.

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Abstract. δ18O tracer measurements of precipitation and stream waters were used to investigate hydrological flow paths and residence times at nested spatial scales in the mesoscale (233 km2 River Feugh catchment in the northeast of Scotland over the 2001-2002 hydrological year. Precipitation δ18O exhibited strong seasonal variation, which although significantly damped by catchment mixing processes, was reflected in stream water outputs at six sampling sites. This allowed δ18O variations to be used to infer the relative influence of soil-derived storm flows with a seasonally variable isotopic s

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Ganssen, G., F. Peeters, B. Metcalfe, et al. "Quantifying sea surface temperature ranges of the Arabian Sea for the past 20 000 years." Climate of the Past Discussions 6, no. 6 (2010): 2795–814. http://dx.doi.org/10.5194/cpd-6-2795-2010.

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Abstract. The oxygen isotopic composition of planktonic foraminifera tests is one of the widest used geochemical tools to reconstruct past changes of physical parameters of the upper ocean. It is common practice to analyze multiple individuals from a mono-specific population and assume that the outcome reflects a mean value of the environmental conditions during calcification of the analyzed individuals. Here we present the oxygen isotope composition of individual specimens of the surface dwelling species Globigerinoides ruber and Globigerina bulloides from sediment cores in the Western Arabia

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Pearson, Ann, Ann P. Mcnichol, Robert J. Schneider, Karl F. Von Reden, and Yan Zheng. "Microscale AMS 14C Measurement at NOSAMS." Radiocarbon 40, no. 1 (1997): 61–75. http://dx.doi.org/10.1017/s0033822200017902.

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Techniques for making precise and accurate radiocarbon accelerator mass spectrometry (AMS) measurements on samples containing less than a few hundred micrograms of carbon are being developed at the NOSAMS facility. A detailed examination of all aspects of the sample preparation and data analysis process shows encouraging results. Small quantities of CO2 are reduced to graphite over cobalt catalyst at an optimal temperature of 605°. Measured 14C/12C ratios of the resulting targets are affected by machine-induced isotopic fractionation, which appears directly related to the decrease in ion curre

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Tobias, Phillip V., John C. Vogel, H. Dieter Oschadleus, Timothy C. Partridge, and Jeffrey K. McKee. "New Isotopic and Sedimentological Measurements of the Thabaseek Deposits (South Africa) and the Dating of the Taung Hominid." Quaternary Research 40, no. 3 (1993): 360–67. http://dx.doi.org/10.1006/qres.1993.1089.

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AbstractEarlier attempts to date the Taung hominid type specimen of Australopithecus africanus Dart yielded conflicting results. Recent faunal studies pointed to an age of 2.3 myr. Radioisotopic results suggested 1.0 myr. New uranium studies reveal that the Thabaseek (the oldest Taung tufa) was not a closed system and that younger uranium entered the tufa after initial deposition, producing an apparent isotopic age younger than the age of deposition. The Thabaseek isotopic dates provide only a terminus ad quem and this technique is therefore not applicable to the older Taung tufas. Delson's da

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Piotrowska, Natalia, Anna Pazdur, Sławomira Pawełczyk, Andrzej Z. Rakowski, Barbara Sensuła, and Konrad Tudyka. "Human Activity Recorded in Carbon Isotopic Composition of Atmospheric CO2 in Gliwice Urban Area and Surroundings (Southern Poland) in the Years 2011–2013." Radiocarbon 62, no. 1 (2019): 141–56. http://dx.doi.org/10.1017/rdc.2019.92.

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ABSTRACTIn this paper, a record of the 14C and 13C isotope content of atmospheric CO2 for Gliwice is presented for samples collected on a weekly basis in the years 2011–2013. In addition, measurements were performed on the early and late wood from the annual rings of pine trees from five sites located 3–6 km from the atmospheric CO2 sampling point. The concentration of 14C in CO2 samples from the air was much lower relative to the concentration of this isotope in “clean air,” indicating a pronounce Suess effect, with a mean Δ14C lower by ca. 60‰ than Jungfraujoch data when the 15% of the highe

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Thomsen, Mette S., and Steinar Gulliksen. "Reduction of CO2-to-Graphite Conversion Time of Organic Materials for 14C AMS." Radiocarbon 34, no. 3 (1992): 330–34. http://dx.doi.org/10.1017/s0033822200063505.

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Graphite is the most common type of target for 14C accelerator mass spectrometry (AMS). It is readily produced by catalytic reduction of CO2, but the presence of a small amount of impurities (e.g., sulfur compounds) may retard the reaction. We have tested some techniques to find a method that reduces the impurity content of CO2 produced by combustion of organic material. We found that using water during combustion reduces the average time for graphite conversion of CO2 from organic matter from >3 h to ca. 2 h. This is the time for graphite production from CO2 obtained by acid hydrolysis of

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Basu, Sourish, Xin Lan, Edward Dlugokencky та ін. "Estimating emissions of methane consistent with atmospheric measurements of methane and δ¹³C of methane". Atmospheric Chemistry and Physics 22, № 23 (2022): 15351–77. http://dx.doi.org/10.5194/acp-22-15351-2022.

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Abstract. We have constructed an atmospheric inversion framework based on TM5-4DVAR to jointly assimilate measurements of methane and δ13C of methane in order to estimate source-specific methane emissions. Here we present global emission estimates from this framework for the period 1999–2016. We assimilate a newly constructed, multi-agency database of CH4 and δ13C measurements. We find that traditional CH4-only atmospheric inversions are unlikely to estimate emissions consistent with atmospheric δ13C data, and assimilating δ13C data is necessary to derive emissions consistent with both measure

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ITO, Motoo, and Scott MESSENGER. "Thermal metamorphic history of a Ca, Al-rich inclusion constrained by high spatial resolution Mg isotopic measurements with NanoSIMS 50L." Meteoritics & Planetary Science 45, no. 4 (2010): 583–95. http://dx.doi.org/10.1111/j.1945-5100.2010.01038.x.

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Fletcher, I. R., A. L. Maggi, K. J. R. Rosman, and N. J. McNaughton. "Isotopic abundance measurements of K and Ca using a wide-dispersion multi-collector mass spectrometer and low-fractionation ionisation techniques." International Journal of Mass Spectrometry and Ion Processes 163, no. 1-2 (1997): 1–17. http://dx.doi.org/10.1016/s0168-1176(96)04540-5.

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DeCarlo, Thomas M., Michael Holcomb, and Malcolm T. McCulloch. "Reviews and syntheses: Revisiting the boron systematics of aragonite and their application to coral calcification." Biogeosciences 15, no. 9 (2018): 2819–34. http://dx.doi.org/10.5194/bg-15-2819-2018.

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Abstract. The isotopic and elemental systematics of boron in aragonitic coral skeletons have recently been developed as a proxy for the carbonate chemistry of the coral extracellular calcifying fluid. With knowledge of the boron isotopic fractionation in seawater and the B∕Ca partition coefficient (KD) between aragonite and seawater, measurements of coral skeleton δ11B and B∕Ca can potentially constrain the full carbonate system. Two sets of abiogenic aragonite precipitation experiments designed to quantify KD have recently made possible the application of this proxy system. However, while dif

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Pazdur, Anna, Mieczyslaw F. Pazdur, Leszek Starkel, and Joachim Szulc. "Stable Isotopes of Holocene Calcareous Tufa in Southern Poland as Paleoclimatic Indicators." Quaternary Research 30, no. 2 (1988): 177–89. http://dx.doi.org/10.1016/0033-5894(88)90022-1.

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The isotopic composition of oxygen in freshwater calcareous tufa seems to be a sensitive indicator of past climatic changes. Results of measurements of δc18O and δc13C in tufa samples dated with the 14C method are used to reconstruct Holocene climatic changes in southern Poland. Values of δc18O obtained on tufa samples from four sites (Raclawka, Rzerzuŝnia, Trzebienice, Sieradowice) representing different hydrodynamic conditions of tufa sedimentation seem to form a selfconsistent series. These values, with some simplifying assumptions concerning the course of tufa sedimentation, were therefore

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Majzlan, Juraj, Maria Brey-Funke, Alexander Malz, Stefan Donndorf, and Rastislav Milovský. "Fluid evolution and mineralogy of Mn-Fe-barite-fluorite mineralizations at the contact of the Thuringian Basin, Thüringer Wald and Thüringer Schiefergebirge in Germany." Geologica Carpathica 67, no. 1 (2016): 3–20. http://dx.doi.org/10.1515/geoca-2016-0001.

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Abstract Numerous small deposits and occurrences of Mn-Fe-fluorite-barite mineralization have developed at the contact of the Thuringian Basin, Thüringer Wald and Thüringer Schiefergebirge in central Germany. The studied mineralizations comprise the assemblages siderite+ankerite-calcite-fluorite-barite and hematite-Mn oxides-calcite-barite, with the precipitation sequence in that order within each assemblage. A structural geological analysis places the origin of the barite veins between the Middle Jurassic and Early Cretaceous. Primary fluid inclusions contain water vapour and an aqueous phase

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Ganssen, G. M., F. J. C. Peeters, B. Metcalfe, et al. "Quantifying sea surface temperature ranges of the Arabian Sea for the past 20 000 years." Climate of the Past 7, no. 4 (2011): 1337–49. http://dx.doi.org/10.5194/cp-7-1337-2011.

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Abstract. The oxygen isotopic composition of planktonic foraminifera tests is one of the widest used geochemical tools to reconstruct past changes of physical parameters of the upper ocean. It is common practice to analyze multiple individuals from a mono-specific population and assume that the outcome reflects a mean value of the environmental conditions during calcification of the analyzed individuals. Here we present the oxygen isotope composition of individual specimens of the surface-dwelling species Globigerinoides ruber and Globigerina bulloides from sediment cores in the Western Arabia

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Pai, Ashok P., Darren Hillegonds, Primo Lara, Chong-xian Pan, and David Shelton. "Calcium metabolism in patients with castration-resistant prostate cancer: Development of a quantitative urinary assay for extent of bone metastasis." Journal of Clinical Oncology 30, no. 5_suppl (2012): 130. http://dx.doi.org/10.1200/jco.2012.30.5_suppl.130.

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130 Background: In patients with metastatic castration-resistant prostate cancer (CRPC), the degree of perturbation from normal bone turnover provides a strong indication of risk for disease progression, skeletal complications and death. Biomarkers of bone cell function and bone collagen degradation provide an integrated index of the underlying disease for patients with bony metastases, but available bone markers are not precise or accurate. In this study, patients with CRPC with bony metastases will consume a single oral calcium-41 dose and the pharmacokinetics of this will be measured over a

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Uchida, Etsuo, Takumi Yokokura, Sota Niki, and Takafumi Hirata. "Geochemical Characteristics and U–Pb Dating of Granites in the Western Granitoid Belt of Thailand." Geosciences 14, no. 5 (2024): 135. http://dx.doi.org/10.3390/geosciences14050135.

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This paper presents the integration of magnetic susceptibility measurements and whole-rock geochemical compositional and Nd–Sr isotopic ratio analyses for granite samples collected from the Ranong, Lam Pi, Ban Lam Ru, and Phuket granite bodies in the Western Granitoid Belt of Thailand. In addition, U–Pb dating was performed on zircons extracted from the samples. All samples are proper granites based on their mineralogical and geochemical characteristics. Two samples collected from the Lam Pi granite body were classified as magnetite-series and I-type. The remaining granite samples were classif

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Michalska, Danuta, and Andrzej Krzyszowski. "Chronology of multicultural site Sowinki in Greater Poland." Geochronometria 44, no. 1 (2017): 30–39. http://dx.doi.org/10.1515/geochr-2015-0047.

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Abstract Sowinki is a village located 35 km south of Poznań, where archaeological research has revealed the remains of settlement from different archaeological periods, ranging from the Mesolithic (ca. six thousand years BC) to the Late Medieval period (ca. 15th century AD). This area, therefore, provides a record of the history of Greater Poland (Poznań) region, tracing back to about seven and a half thousand years ago. Samples of bones and wood were collected from different features, including mostly cellar pits, refuse pits and grave pits. Eight of the samples, all collected from grave pits

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Ramnarine, R., R. P. Voroney, C. Wagner-Riddle та K. E. Dunfield. "Carbonate removal by acid fumigation for measuring the δ13C of soil organic carbon". Canadian Journal of Soil Science 91, № 2 (2011): 247–50. http://dx.doi.org/10.4141/cjss10066.

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Ramnarine, R., Voroney, R. P., Wagner-Riddle, C. and Dunfield. K. E. 2011. Carbonate removal by acid fumigation for measuring the δ 13 C of soil organic carbon. Can. J. Soil Sci. 91: 247–250. Complete removal of carbonates from calcareous soil samples is critical for accurate measurement of the quantity and isotopic signature (δ13C) of soil organic carbon (SOC). Carbonates confound SOC and δ13C measurements because they have δ13C values ranging from −10‰ to +2‰, whereas those of soil organic carbon range from −27‰ to −13‰, depending on the source of plant residues. Commonly used methods for re

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Simon, S. A., P. Labarca, and R. Robb. "Activation by saccharides of a cation-selective pathway on canine lingual epithelium." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 256, no. 2 (1989): R394—R402. http://dx.doi.org/10.1152/ajpregu.1989.256.2.r394.

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Responses of isolated canine lingual epithelium in an Ussing chamber to D-glucose and fructose reveal events associated with taste transduction. With the use of isotopic flux studies, together with ion substitution and pharmacological and voltage clamp measurements, it was found that the stimulation of ion transport by D-glucose arises from an increase in the influx of cations through a cation-selective pathway. This influx of cations is completely inhibited by 0.1 mM amiloride. The stimulation of transport by fructose in 0.05 M KCl and by D-glucose in 0.05 M RbCl was also inhibited by amilori

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Guehl, J. M., G. Aussenac, J. Bouachrine, et al. "Sensitivity of leaf gas exchange to atmospheric drought, soil drought, and water-use efficiency in some Mediterranean Abies species." Canadian Journal of Forest Research 21, no. 10 (1991): 1507–15. http://dx.doi.org/10.1139/x91-211.

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The responses of CO2 assimilation rate (A), transpiration rate (E), and leaf conductance (g) to increasing leaf to air water vapor concentration difference (ΔW) were investigated (i) using excised shoots from mature trees of Abiesalba, Abiescephalonica, Abiesmarocana, and Abiesnordmanniana and (ii) in situ on a mature tree of Abiesbornmulleriana. Gas-exchange responses to increasing soil drought were also studied in plants of A. bornmulleriana, A. cephalonica, and Cedrusatlantica. Stable carbon isotope composition measurements were carried out on annual growth rings of A. bornmulleriana to est

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Ballantyne, A. P., J. Brahney, D. Fernandez, C. L. Lawrence, J. Saros, and J. C. Neff. "Biogeochemical response of alpine lakes to recent changes in dust deposition." Biogeosciences Discussions 7, no. 6 (2010): 8723–61. http://dx.doi.org/10.5194/bgd-7-8723-2010.

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Abstract. The deposition of dust has recently increased significantly over some regions of the western US. Here we explore how changes in dust deposition have affected the biogeochemistry of two alpine watersheds in Colorado, US. We first reconstruct recent changes in the mass accumulation rate of sediments and then we use isotopic measurements in conjunction with a Bayesian mixing model to infer that approximately 95% of the inorganic fraction of lake sediments is derived from dust. Elemental analyses of modern dust indicate that dust is enriched in Ca, Cr, Cu, Mg, Ni, and in one watershed, F

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Ballantyne, A. P., J. Brahney, D. Fernandez, C. L. Lawrence, J. Saros, and J. C. Neff. "Biogeochemical response of alpine lakes to a recent increase in dust deposition in the Southwestern, US." Biogeosciences 8, no. 9 (2011): 2689–706. http://dx.doi.org/10.5194/bg-8-2689-2011.

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Abstract. The deposition of dust has recently increased significantly over some regions of the western US. Here we explore how changes in dust deposition have affected the biogeochemistry of two alpine watersheds in Colorado, US. We first reconstruct recent changes in the mass accumulation rate of sediments and then we use isotopic measurements in conjunction with a Bayesian mixing model to infer that approximately 95% of the inorganic fraction of lake sediments is derived from dust. Elemental analyses of modern dust indicate that dust is enriched in Ca, Cr, Cu, Mg, Ni, and in one watershed, F

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Carbone, S., T. Onasch, S. Saarikoski, et al. "Characterization of trace metals with the SP-AMS: detection and quantification." Atmospheric Measurement Techniques Discussions 8, no. 6 (2015): 5735–68. http://dx.doi.org/10.5194/amtd-8-5735-2015.

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Abstract. A method to detect and quantify mass concentrations of metals by the Aerodyne Soot Particle – Aerosol Mass Spectrometer (SP-AMS) was developed and evaluated in this study. The generation of monodisperse Regal black (RB) test particles with trace amounts of 13 different metals (Na, Al, Ca, V, Cr, Fe, Mn, Ni, Cu, Zn, Rb, Sr and Ba) allowed the determination of the relative ionization efficiency of each metal (RIEmeas). The ratio RIEtheory / RIEmeas presented values larger than the unity for Na, Rb, Ca, Sr and Ba due to the thermal surface ionization (TSI) on the surface of the RB parti

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