Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “LEAD ISOTOPES”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Linking cases of illegal shootings of the endangered California condor using stable lead isotope analysis

Lead poisoning is preventing the recovery of the critically endangered California condor (Gymnogyps californianus) and lead isotope analyses have demonstrated that ingestion of spent lead ammunition is the principal source of lead poisoning in condors. Over an 8 month period in 2009, three lead-poisoned condors were independently presented with birdshot embedded in their tissues, evidencing they had been shot. No information connecting these illegal shooting events existed and the timing of the shooting(s) was unknown. Using lead concentration and stable lead isotope analyses of feathers, blood, and recovered birdshot, we observed that: i) lead isotope ratios of embedded shot from all three birds were measurably indistinguishable from each other, suggesting a common source; ii) lead exposure histories re-constructed from feather analysis suggested that the shooting(s) occurred within the same timeframe; and iii) two of the three condors were lead poisoned from a lead source isotopically indistinguishable from the embedded birdshot, implicating ingestion of this type of birdshot as the source of poisoning. One of the condors was subsequently lead poisoned the following year from ingestion of a lead buckshot (blood lead 556 µg/dL), illustrating that ingested shot possess a substantially greater lead poisoning risk compared to embedded shot retained in tissue (blood lead ∼20 µg/dL). To our knowledge, this is the first study to use lead isotopes as a tool to retrospectively link wildlife shooting events. - Highlights: • We conducted a case-based analysis of illegal shootings of California condors. • Blood and feather Pb isotopes were used to reconstruct the illegal shooting events. • Embedded birdshot from the three condors had the same Pb isotope ratios. • Feather and blood Pb isotopes indicated that the condors were shot in a common event. • Ingested shot causes substantially greater lead exposure compared to embedded shot.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1978

Lead isotope systematics of mare basalt 75075

Uranium, thorium and isotopic lead data are reported for two bulk samples and separated pyroxene, ilmenite and plagioclase from basalt 75075. In a concordia diagram the whole rock, ilmenite and four pyroxene samples define a chord intersecting the concordia curve at approximately 4.25 and 2.8 AE. Three plagioclase samples plot distinctly off the chord. The crystallization age of 75075 is accurately determined at 3.74 AE by Rb-Sr, Sm-Nd and K-Ar measurements from other laboratories. It is not possible to adjust the isotopic composition of initial lead so as to reconcile the U-Pb data with a crystallization age of 3.74 AE. The data therefore indicate some type of post-crystallization disturbance of the U-Pb system that is not detected by the other systems. The 75075 data are one of the few examples of this type of age pattern found on the moon. If the disturbance was a single event, it probably occurred around 2.8 AE ago, the time indicated by the pyroxene, whole rock and ilmenite data.

Chen, J. H.↗
NASA NTRS1974

Lead isotope systematics of some Apollo 17 soils and some separated components from 76501

Isotopic lead data from bulk samples of Apollo 17 soils were analyzed, and they define a chord in a concordia diagram, showing the presence of a component or components containing excess radiogenic lead with Pb-207/Pb-206 equal to about 1.32. The chord is distinctly different from the cataclysm chord, for which Pb-207/Pb-206 is approximately 1.45. Nitric acid analysis of plagioclase indicates lead ages of around 4.35 AE, in agreement with previous findings. Agglutinates from soil 76501,34 show loss of approximately 15% of lead.

Church, S. E.↗
NASA NTRS1977

Lead isotope studies of mare basalt 70017

Uranium, thorium, and isotopic lead data for components of basalt 70017 are reported, and it is found that the whole rock, pyroxene, and ilmenite points in a concordia diagram plot along a chord intersecting the curve at 3.7 and 4.33 eons. The plagioclase data do not seem to lie on this line. The data for 70017 appear to plot along a distinctly different chord in a concordia diagram than do the data for 75055 and 75035, two other Apollo 17 mare basalts. The lead data are in accord with Sm-Nd results. A 3.7 eon crystallization age for 70017 would be consistent with the same kind of parentless lead that is indicated by previous studies of soils and soil breccias from stations at Taurus-Littrow. The Th/U ratio in ilmenite is 2.2, and the concentrations of these two elements are approximately twice those in pyroxene.

Mattinson, J. M.↗
NASA NTRS1979

Lead isotope systematics of three Apollo 17 mare basalts

The paper deals with new and more accurate determinations of uranium, thorium, and isotopic lead data for five bulk samples and separate pyroxene, ilmenite, and plagioclase from basalt 71055. In a concordia diagram, the samples suggest a postcrystallization disturbance of the U-Pb systems of the rock. There is no compelling reason, from U-Pb data, to believe that the moon is younger than 4.55 AE.

Tilton, G. R.↗
DOE OSTI2016

Deformation properties of lead isotopes

The deformation properties of a long lead isotopic chain up to the neutron drip line are analyzed on the basis of the energy density functional (EDF) in the FaNDF{sup 0} Fayans form. The question of whether the ground state of neutron-deficient lead isotopes can have a stable deformation is studied in detail. The prediction of this deformation is contained in the results obtained on the basis of the HFB-17 and HFB-27 Skyrme EDF versions and reported on Internet. The present analysis reveals that this is at odds with experimental data on charge radii and magnetic moments of odd lead isotopes. The Fayans EDF version predicts a spherical ground state for all light lead isotopes, but some of them (for example, {sup 180}Pb and {sup 184}Pb) prove to be very soft—that is, close to the point of a phase transition to a deformed state. Also, the results obtained in our present study are compared with the predictions of some other Skyrme EDF versions, including SKM*, SLy4, SLy6, and UNE1. By and large, their predictions are closer to the results arising upon the application of the Fayans functional. For example, the SLy4 functional predicts, in just the same way as the FaNDF{sup 0} functional, a spherical shape for all nuclei of this region. The remaining three Skyrme EDF versions lead to a deformation of some light lead isotopes, but their number is substantially smaller than that in the case of the HFB-17 and HFB-27 functionals. Moreover, the respective deformation energy is substantially lower, which gives grounds to hope for the restoration of a spherical shape upon going beyond the mean-field approximation, which we use here. Also, the deformation properties of neutron-rich lead isotopes are studied up to the neutron drip line. Here, the results obtained with the FaNDF{sup 0} functional are compared with the predictions of the HFB-17, HFB-27, SKM*, and SLy4 Skyrme EDF versions. All of the EDF versions considered here predict the existence of a region where neutron-rich lead isotopes undergo deformations, but the size of this region is substantially different for the different functionals being considered. Once again, it is maximal for the HFB-17 and HFB-27 functionals, is substantially narrower for the FaNDF{sup 0} functional, and is still narrower for the SKM* and SLy4 functionals. The two-neutron drip line proved to be A{sub drip}{sup 2n} = 266 for all of the EDF versions considered here, with the exception of SKM*, for which it is shifted to A{sub drip}{sup 2n}(SKM*) = 272.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Improvements of Nuclear Data Evaluations for Lead Isotopes in Support of Next Generation Lead-Cooled Fast Systems

The neutron evaluation of the isotopes that comprise natural lead were undertaken as a part of DOE-NEUP Project #19-16739. The goal of the project was to update the neutron cross sections to account for new differential measurements and incorporate the most up-to-date physics. Shortcomings in the lead cross sections was made known by several independent reports. The work performed here repeated the simulation of all the “benchmark” validation systems and concluded that the major issue is the scattering cross sections in the major lead isotopes above 100 keV. Re-evaluation of 206,207,208 Pb included both the resolved resonance region and fast region evaluations of the cross sections. Combined these regions cover energies from thermal to 20 MeV. The most drastic improvement is the resolved resonance region evaluation of 208 Pb which is now extended from 1.0 to 1.5 MeV. Parameterization of these resonances in the R-matrix provides a superior reconstruction of not only the experimental cross section but also the scattering distributions via the Blatt-Biedenharn formalism. Fast region evaluations of the three major isotopes were done to include new inelastic experimental data from the neutron Time-of-Flight facility at CERN. The culmination of all the changes to the cross section is a drastic improvement in the scattering kernel as shown in Rensselaer Polytechnic Institute (RPI) Quasi-Differential scattering measurements and improved prediction of keff for fast integral experiments. Alongside the new cross sections, new nuclear data covariance (uncertainties) have been computed and are included in the evaluation. Little is changed in the magnitude of the uncertainties but the correlations within the covariance display non-trivial changes. The new evaluations of 206,207,208 Pb have been submitted to the National Nuclear Data Center to be included in the ENDF/B-VIII.1 library. While the cross sections have been updated extensively, knowledge and modeling of the cross sections between 1.0 and 3.0 MeV for the isotopes remain a challenge. Most notably is the double differential elastic cross section for 208 Pb and 206 Pb. New quasi-differential measurements for pure samples of these two nuclei would go a long way in reducing compensating errors in the evaluations. Qualitatively, the project has produced a prosperous collaboration between the nuclear data group at RPI with staff scientists at Brookhaven National Laboratory, Naval Nuclear Laboratory, Oak Ridge National Laboratory, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and Sandia National Laboratories. Quantitatively this is reflected in seven conference presentations, at least one journal submission, and one doctoral thesis.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1983

Lead isotope systematics of some igneous rocks from the Egyptian Shield

Lead isotope data on whole-rock samples and two feldspar separates for a variety of Pan-African (late Precambrian) igneous rocks for the Egyptian Shield are presented. It is pointed out that the eastern desert of Egypt is a Late Precambrian shield characterized by the widespread occurrence of granitic plutons. The lead isotope ratios may be used to delineate boundaries between Late Precambrian oceanic and continental environments in northeastern Africa. The samples belong to three groups. These groups are related to a younger plutonic sequence of granites and adamellites, a plutonic group consisting of older tonalites to granodiorites, and the Dokhan volcanic suite.

Gillespie, J. G.↗
DOE OSTI2019

Spallation reactions induced by 4.4 GeV deuterons on lead isotopes

Independent and cumulative production cross sections for radioactive nuclear fragments from the deuteron-irradiation of isotopically enriched lead (204Pb, 206Pb, 207Pb, and 208Pb) targets were obtained for the first time. The experiment has been performed with a 4.4 GeV deuteron beam from the Nuclotron of the Laboratory of High Energy Physics (LHE), Joint Institute for Nuclear Research (JINR) at Dubna. The production cross sections of target fragments were determined by off-line γ-ray spectroscopy. Charge dispersion and mass-yield distributions were deduced from these data. The results are discussed in terms of the relative importance of different reaction mechanisms (evaporation–spallation, fission and multifragmentation). Comparison of our results with the data from the reaction induced by protons of about the same kinetic energy per nucleon, has been performed. The coexistence of the different decay modes in the formation of the reaction residues, such as spallation, fission and multifragmentation is suggested.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1989

Neodymium and lead isotope evidence for enriched early Archean crust in North America

Neodymium and lead isotope measurements and uranium-lead zircon geochronology from Archaean gneisses of the Slave Province in the Northwest Territories of Canada are reported. The gneisses contain zircons with cores older than 3.842 Gyr and an epsilon(Nd) (3.7 Gyr) of - 4.8. This is the oldest reported chondritic model age for a terrestrial sample and provides evidence for strongly enriched pre-3.8-Gyr crust, a reservoir complementary to the depleted mantle already in existence by 3.8 Gyr before the present.

Bowring, Samuel A.↗
DOE OSTI2017

Use of multiple tools including lead isotopes to decipher sources of ozone and reactive mercury to urban and rural locations in Nevada, USA

Ambient air particulate matter (< 2.5 μm in diameter) samples were collected on two different filter types in 2014 and 2015 over 24 h periods and analyzed for reactive mercury (gaseous oxidized mercury + particulate bound mercury) concentrations and lead isotopes to determine sources of pollution to three sites in Nevada, USA. Two sites were located on the western edge of Nevada (Reno, urban, 1370 m and Peavine Peak, rural, high elevation, 2515 m); the third location was ~ 485 km east in rural Great Basin National Park, NV (2061 m). Reactive mercury samples were collected on cation exchange membranes simultaneously with lead samples, collected on Teflon membranes. Lead isotopic ratios have previously identified trans-Pacific lead sources based on the 206/207 and 208/207 lead ratios. Influence from trans-Pacific air masses was higher from March to June associated with long-range transport of pollutants. Spring months are well known for increased transport across the Pacific; however, fall months were also influenced by trans-Pacific air masses in this study. Western North American background ozone concentrations have been measured and modeled at 50 to 55 ppbv. Median ozone concentrations at both rural sites in Nevada were within this range. Sources leading to enhancements in ozone of 2 to 18 ppbv above monthly medians in Nevada included emissions from Eurasia, regional urban centers, and global and regional wildfires, resulting in concentrations close to the USA air quality standard. At the high elevation locations, ozone was derived from pollutants being transported in the free troposphere that originate around the globe; however, Eurasia and Asia were dominant sources to the Western USA. Negative correlations between reactive mercury and percent Asian lead, Northern Eurasia and East Asia trajectories indicated reactive mercury concentrations at the two high elevation sites were produced by oxidants from local, regional, and marine boundary layer sources.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Lead isotopic compositions of airborne particulates collected from snow and from dry deposition in the East River Watershed, Colorado and at the Southern Sierra Critical Zone Observatory, California

The data set consists of lead (Pb) isotopic ratios (206Pb/207Pb and 208Pb/207Pb, as well as 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) for particulate samples collected from snow and dry deposition. This was part of a study (O’Day et al. 2020) that was looking at the speciation of phosphorous in splits of these samples to evaluate the flux and bio-availability of phosphorous to the mountain sites in the study. The Pb isotopic data allow sourcing of long-range transported Pb, specifically the fraction of Pb sourced in Asia, and so a comparison of the relative distances of PM sources between the high and low elevation sites. Samples were collected at the East River Watershed, CO (dry deposition collected over Sept.-Oct. 2016, show sampling winter 2017) and at the Southern Sierra Critical Zone Observatory (dry deposition collected over Sept-Nov 2016, July-Sept 2017, June-July 2017). The data includes Pb concentration data, as well as calculated fraction of the Pb sourced in Asia. This data set was published in part in O’Day et al. (2020) Phosphorus Speciation in Atmospherically Deposited Particulate Matter and Implications for Terrestrial Ecosystem Productivity. ES&T, https://dx.doi.org/10.1021/acs.est.9b06150

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

Successful application of lead isotopes in source apportionment, legal proceedings, remediation and monitoring

In late 2006, the seaside community in Esperance Western Australia was alerted to thousands of native bird species dying. The source of the lead (Pb) was determined by Pb isotopes to derive from the handling of Pb carbonate concentrate through the Port, which began in July 2005. Concern was expressed for the impact of this on the community. Our objectives were to employ Pb isotope ratios to evaluate the source of Pb in environmental samples for use in legal proceedings, and for use in remediation and monitoring. Isotope measurements were undertaken of bird livers, plants, drinking water, soil, harbour sediments, air, bulk ceiling dust, gutter sludge, surface swabs and blood. The unique lead isotopic signature of the contaminating Pb carbonate enabled diagnostic apportionment of lead in samples. Apart from some soil and water samples, the proportion of contaminating Pb was >95% in the environmental samples. Lead isotopes were critical in resolving legal proceedings, are being used in the remediation of premises, were used in monitoring of workers involved in the decontamination of the storage facility, and monitoring transport of the concentrate through another port facility. Air samples show the continued presence of contaminant Pb, more than one year after shipping of concentrate ceased, probably arising from dust resuspension. Brief details of the comprehensive testing and cleanup of the Esperance community are provided along with the role of the Community. Lead isotopic analyses can provide significant benefits to regulatory agencies, interested parties, and the community where the signature is able to be characterised with a high degree of certainty. - Highlights: Black-Right-Pointing-Triangle Lead carbonate concentrate. Black-Right-Pointing-Triangle Successful use of Pb isotopes in identifying sources of Pb arising from transport and shipping. Black-Right-Pointing-Triangle Use of Pb isotopes in legal proceedings and their use in cleanup of residences. Black-Right-Pointing-Triangle Use of Pb isotopes in cleanup of a residual 9000 tonnes of Pb carbonate and in ongoing monitoring.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1988

Geochronological and lead-isotope evidences for rapid crust formation in middle-proterozoic time: The Labrador example

Extensive U-Pb geochronological studies in the Grenville and Makkovik provinces have shown that eastern Labrador is underlain by two distinct crustal blocks. In order to substantiate the juvenile character of the middle-Proterozoic crustal block, the isotopic compositon of lead in leached k-feldspars from the same rocks were analyzed. The results of the analysis are briefly discussed.

Schaerer, Urs↗
NASA NTRS1976

Lead isotopic studies of lunar soils - Their bearing on the time scale of agglutinate formation

Fines (smaller than 75 microns) and bulk soil were studied to analyze loss of volatile lead; losses of the order of 10% to 30% radiogenic lead during the production of agglutinates are assessed. Lead isotope data from fine-agglutinate pairs are analyzed for information on the time scale of micrometeorite bombardment, from the chords generated by the data in concordia diagrams. Resulting mean lead loss ages were compared to spallogenic gas exposure ages for all samples. Labile parentless radiogenic Pb residing preferentially on or in the fines is viewed as possibly responsible for aberrant lead loss ages. Bulk soils plot above the concordia curve (in a field of excess radiogenic Pb) for all samples with anomalous ages.

Church, S. E.↗
DOE OSTI2020

Variation of lead isotopic composition and atomic weight in terrestrial materials (IUPAC Technical Report)

The isotopic composition and atomic weight of lead are variable in terrestrial materials because its three heaviest stable isotopes are stable end-products of the radioactive decay of uranium ( 238 U to 206 Pb; 235 U to 207 Pb) and thorium ( 232 Th to 208 Pb). The lightest stable isotope, 204 Pb, is primordial. These variations in isotope ratios and atomic weights provide useful information in many areas of science, including geochronology, archaeology, environmental studies, and forensic science. While elemental lead can serve as an abundant and homogeneous isotopic reference, deviations from the isotope ratios in other lead occurrences limit the accuracy with which a standard atomic weight can be given for lead. In a comprehensive review of several hundred publications and analyses of more than 8000 samples, published isotope data indicate that the lowest reported lead atomic weight of a normal terrestrial materials is 206.1462 ± 0.0028 (k = 2), determined for a growth of the phosphate mineral monazite around a garnet relic from an Archean high-grade metamorphic terrain in north-western Scotland, which contains mostly 206 Pb and almost no 204 Pb. The highest published lead atomic weight is 207.9351 ± 0.0005 (k = 2) for monazite from a micro-inclusion in a garnet relic, also from a high-grade metamorphic terrain in north-western Scotland, which contains almost pure radiogenic 208 Pb. When expressed as an interval, the lead atomic weight is [206.14, 207.94]. It is proposed that a value of 207.2 be adopted for the single lead atomic-weight value for education, commerce, and industry, corresponding to previously published conventional atomic-weight values.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗