Variations In Isotopic Abundances Research Articles

Big data and environmental sustainability based integrated framework for isotope hydrology applications in India

Water contains environmental isotopes, which can act as tracers to study the source, origin, and distribution of water in the hydrological cycle. Recently, the environmental isotopes have been widely applied in hydrological investigations and it is established that the spatio-temporal variations in isotopic abundance provide valuable information to enhance the qualitative and quantitative understanding of hydrological processes such as mixing of different flow components and recharge rate, identify origin of water, delineation of groundwater recharge zones, geothermal dynamics, paleo-recharge and many others. Here, a review of case studies is presented to highlight the impact of isotope applications in water resource management in India. Along with a review of studies across India, a study is carried out for the assessment of groundwater interactions using isotopes of water (18O, 2H and 3H) in dry/semi-arid region (Jaipur) and wet/humid region (Guwahati). The major outcome of the study is the formulation of groundwater baseline for Guwahati (post-monsoon in 2017 and 2018: δD= 4.98 δ18O + 7.50) and Jaipur (post-monsoon and pre-monsoon in 2018: δD= 4.85 δ18O – 9.49). The results indicate that tritium has strong negative correlation (R2 = 0.59) with depth in Jaipur, indicating increasing groundwater age with depth. In Guwahati, the tritium shows weak positive (R2= 0.25) relationship which might be because of the presence of sandyclay layers in the shallow zone limiting vertical recharge to aquifer. Moreover, based upon the review and isotope results of the two study sites, a novel integrated framework for isotope hydrology application for India is proposed, incorporating the principles of environmental sustainability, economic efficiency and social equity. The isotopic techniques in hydrological investigations not only complements the traditional methods used in water resource management but also provides new insights and an enhanced understanding of the hydrological systems.

Local vibrational modes of natural isotopes of substitutional oxygen in CdTe

We investigated the localized vibrational modes (LVM) of natural oxygen containing $^{16}$O, $^{17}$O, and $^{18}$O isotopes at a substitutional tellurium site in cadmium telluride using infrared absorption spectroscopy at cryogenic temperatures. The main absorption peak observed at 350 cm$^{-1\, }$was formerly attributed to a fundamental LVM mode ($\nu _{0})$ of oxygen at a tellurium site. The relatively weak absorption peaks observed at 331 cm$^{-1\, }$and 340 cm$^{-1\, }$are assigned as the same $\nu_{0}$ mode of the $^{17}$O and $^{18}$O isotopes, respectively, based on their relative intensities and spectral positions. The spectral positions were confirmed with theoretical calculations using a linear chain model where the peak position at 350 cm$^{-1}$ was taken as the reference for the $^{16}$O isotope. From a least square analysis of the observed peak positions we were able to calculate the force constants from perturbation theory. A Lorentzian line shape analysis of each $\nu_{0}$ absorption peak, considering the effects of isotopic mass and natural abundance variations of the host Cd atoms, was also carried out to further confirm their assignments. Reasonably good line shape fittings were obtained for $\nu _{0}$ modes of all isotopes of oxygen.

Nanoscale Spatially Resolved Mapping of Uranium Enrichment

Spatially resolved analysis of uranium (U) isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving subnanometer-scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography—a three-dimensional nanoscale characterisation technique—we demonstrate unprecedented nanoscale mapping of U isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (~100 nm3) of depleted and low-enriched U alloyed with 10 wt% molybdenum that has different nominal enrichments of 0.20 and 19.75% 235U, respectively. We map enrichment in various morphologies of a U carbide phase, the adjacent γ-UMo matrix, and across interfaces (e.g., carbide/matrix, grain boundary). Results indicate the U carbides were formed during casting, rather than retained from either highly enriched or depleted U feedstock materials. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origins and thermomechanical processing routes.

Development of a non-destructive isotopic analysis method by gamma-ray emission measurement after negative muon irradiation

Variations in isotopic abundance provide useful information for various scientific fields. Herein we performed a feasibility study by non-destructive isotopic analysis of negative muons. We irradiated two lead plate samples, one with the natural isotopic composition and one enriched with 208Pb, with negative muons and observed the gamma rays from 208Tl with a half-life of 3 min generated via muon absorption by 208Pb during muon irradiation. The isotopic abundance of 208Pb in natPb was successfully determined without sample destruction from the gamma ray intensity to be 69%, which agreed well with the mass spectrometry results.

Nanoscale Spatially Resolved Mapping of Uranium Enrichment in Actinide-Bearing Materials

Spatially resolved analysis of uranium isotopes in small volumes of actinide-bearing materials is critical for a variety of technical disciplines, including earth and planetary sciences, environmental monitoring, bioremediation, and the nuclear fuel cycle. However, achieving sub-nanometer scale spatial resolution for such isotopic analysis is currently a challenge. By using atom probe tomography, a three dimensional nanoscale characterization technique, we demonstrate unprecidented nanoscale mapping of uranium isotopic enrichment with high sensitivity across various microstructural interfaces within small volumes (100 nm3) of depleted and low enriched uranium alloyed with 10 wt % molybdenum with different nominal enrichments of 0.20 and 19.75% 235U respectively. The approach presented here can be applied to study nanoscale variations of isotopic abundances in the broad class of actinide-bearing materials, providing unique insights into their origin and thermo-mechanical processing routes.

Erratum to: Isotope-abundance variations and atomic weights of selected elements: 2016 (IUPAC Technical Report)

Erratum to: Isotope-abundance variations and atomic weights of selected elements: 2016 (IUPAC Technical Report)

Isotope-Abundance Variations and Atomic Weights of Selected Elements: 2016 (IUPAC Technical Report)

Isotope-Abundance Variations and Atomic Weights of Selected Elements: 2016 (IUPAC Technical Report)

13CO/C18O Gradients across the Disks of Nearby Spiral Galaxies

Abstract We use the IRAM Large Program EMPIRE and new high-resolution ALMA data to measure 13CO(1-0)/C18O(1-0) intensity ratios across nine nearby spiral galaxies. These isotopologues of 12CO are typically optically thin across most of the area in galaxy disks, and this ratio allows us to gauge their relative abundance due to chemistry or stellar nucleosynthesis effects. Resolved 13CO/C18O gradients across normal galaxies have been rare due to the faintness of these lines. We find a mean 13CO/C18O ratio of 6.0 ± 0.9 for the central regions of our galaxies. This agrees well with results in the Milky Way, but differs from results for starburst galaxies (3.4 ± 0.9) and ultraluminous infrared galaxies (1.1 ± 0.4). In our sample, the 13CO/C18O ratio consistently increases with increasing galactocentric radius and decreases with increasing star formation rate surface density. These trends could be explained if the isotopic abundances are altered by fractionation; the sense of the trends also agrees with those expected for carbon and oxygen isotopic abundance variations due to selective enrichment by massive stars.

Isotope-Abundance Variations and Atomic Weights of Selected Elements: 2016 (IUPAC Technical Report)

Isotope-Abundance Variations and Atomic Weights of Selected Elements: 2016 (IUPAC Technical Report)

Isotope-abundance variations and atomic weights of selected elements: 2016 (IUPAC Technical Report)

Abstract There are 63 chemical elements that have two or more isotopes that are used to determine their standard atomic weights. The isotopic abundances and atomic weights of these elements can vary in normal materials due to physical and chemical fractionation processes (not due to radioactive decay). These variations are well known for 12 elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, magnesium, silicon, sulfur, chlorine, bromine, and thallium), and the standard atomic weight of each of these elements is given by IUPAC as an interval with lower and upper bounds. Graphical plots of selected materials and compounds of each of these elements have been published previously. Herein and at the URL http://dx.doi.org/10.5066/F7GF0RN2, we provide isotopic abundances, isotope-delta values, and atomic weights for each of the upper and lower bounds of these materials and compounds.

Assessment of international reference materials for isotope-ratio analysis (IUPAC Technical Report)

AbstractSince the early 1950s, the number of international measurement standards for anchoring stable isotope delta scales has mushroomed from 3 to more than 30, expanding to more than 25 chemical elements. With the development of new instrumentation, along with new and improved measurement procedures for studying naturally occurring isotopic abundance variations in natural and technical samples, the number of internationally distributed, secondary isotopic reference materials with a specified delta value has blossomed in the last six decades to more than 150 materials. More than half of these isotopic reference materials were produced for isotope-delta measurements of seven elements: H, Li, B, C, N, O, and S. The number of isotopic reference materials for other, heavier elements has grown considerably over the last decade. Nevertheless, even primary international measurement standards for isotope-delta measurements are still needed for some elements, including Mg, Fe, Te, Sb, Mo, and Ge. It is recommended that authors publish the delta values of internationally distributed, secondary isotopic reference materials that were used for anchoring their measurement results to the respective primary stable isotope scale.

Variations in lead isotopic abundances in Sprague-Dawley rat tissues: possible reason of formation.

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

Recent Progress in Presolar Grain Studies.

Presolar grains are stardust that condensed in stellar outflows or stellar ejecta, and was incorporated in meteorites. They remain mostly intact throughout the journey from stars to the earth, keeping information of their birthplaces. Studies of presolar grains, which started in 1987, have produced a wealth of information about nucleosynthesis in stars, mixing in stellar ejecta, and temporal variations of isotopic and elemental abundances in the Galaxy. Recent instrumental advancements in secondary ion mass spectrometry (SIMS) brought about the identification of presolar silicate grains. Isotopic and mineralogical investigations of sub-μm grains have been performed using a combination of SIMS, transmission electron microscopy (TEM) and focused ion beam (FIB) techniques. Two instruments have been developed to study even smaller grains (∼50 nm) and measure isotopes and elements of lower abundances than those in previous studies.

Si ISOTOPE HOMOGENEITY OF THE SOLAR NEBULA

The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in 29Si/28Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of 29Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the calcium–aluminum-rich inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

INTERSTELLAR DUST PROPERTIES OF M51 FROMAKARIMID-INFRARED IMAGES

The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in 29Si/28Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of 29Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the Calcium-Aluminum-rich Inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

Measurement of Isotope Abundance Variations in Nature by Gravimetric Spiking Isotope Dilution Analysis (GS-IDA)

Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

Stable Nitrogen and Carbon Isotope Ratios Indicate Traditional and Market Food Intake in an Indigenous Circumpolar Population 3

The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yup'ik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (δ15N and δ13C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. First, we analyzed the δ15N and δ13C values of a comprehensive sample of Yup'ik foods. We found that δ15N values were elevated in fish and marine mammals and that δ13C values were elevated in market foods containing corn or sugar cane carbon. Second, we evaluated the associations between RBC δ15N and δ13C values and self-reported measures of traditional and market food intake (n = 230). RBC δ15N values were correlated with intake of fish and marine mammals (r = 0.52; P < 0.0001). RBC δ13C values were correlated with intake of market foods made from corn and sugar cane (r = 0.46; P < 0.0001) and total market food intake (r = 0.46; P < 0.0001). Finally, we assessed whether stable isotope ratios captured population-level patterns of traditional and market intake (n = 1003). Isotopic biomarkers of traditional and market intake were associated with age, community location, sex, and cultural identity. Self-report methods showed variations by age and cultural identity only. Thus, stable isotopes show potential as biomarkers for monitoring dietary change in indigenous circumpolar populations.

Isotopic Ag–Cu–Pb record of silver circulation through 16th–18th century Spain

Estimating global fluxes of precious metals is key to understanding early monetary systems. This work adds silver (Ag) to the metals (Pb and Cu) used so far to trace the provenance of coinage through variations in isotopic abundances. Silver, copper, and lead isotopes were measured in 91 coins from the East Mediterranean Antiquity and Roman world, medieval western Europe, 16th-18th century Spain, Mexico, and the Andes and show a great potential for provenance studies. Pre-1492 European silver can be distinguished from Mexican and Andean metal. European silver dominated Spanish coinage until Philip III, but had, 80 y later after the reign of Philip V, been flushed from the monetary mass and replaced by Mexican silver.

Story one: Chemists want you to know that atomic weights aren't constant: Revisions reflect variations in abundances of isotopes

Science NewsVolume 179, Issue 3 p. 5-6 In the News Story one: Chemists want you to know that atomic weights aren't constant: Revisions reflect variations in abundances of isotopes Rachel Ehrenberg, Rachel EhrenbergSearch for more papers by this author Rachel Ehrenberg, Rachel EhrenbergSearch for more papers by this author First published: 20 January 2011 https://doi.org/10.1002/scin.5591790304AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume179, Issue329 January 2011Pages 5-6 RelatedInformation

Environmental and Biomedical Applications of Natural Metal Stable Isotope Variations

Metal stable isotopes are now being used to trace metal contaminants in the environment and as indicators of human systemic function where metals play a role. Stable isotope abundance variations provide information about metal sources and the processes affecting metals in complex natural systems, complementing information gained from surrogate tracers, such as metal abundance ratios or biochemical markers of metal metabolism. The science is still in its infancy, but the results of initial studies confirm that metal stable isotopes can provide a powerful tool for forensic and biomedical investigations.