DOCSLIB.ORG

Uncertainties in Cancer Risk Coefficients for Environmental Exposure to Radionuclides

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Uncertainties in Cancer Risk Coefficients for Environmental Exposure to Radionuclides OAK RIDGE ORNL/TM-2006/583 NATIONAL LABORATORY MANAGED BY UT-BATTELLE FOR THE DEPARTMENT OF ENERGY Uncertainties in Cancer Risk Coefficients for Environmental Exposure to Radionuclides An Uncertainty Analysis for Risk Coefficients Reported in Federal Guidance Report No. 13 January 2007 Prepared by D. J. Pawela R. W. Leggettb K. F. Eckermanb C. B. Nelsona aOffice of Radiation and Indoor Air U.S. Environmental Protection Agency Washington, DC 20460 bOak Ridge National Laboratory Oak Ridge, Tennessee 37831 DOCUMENT AVAILABILITY Reports produced after January 1, 1996, are generally available free via the U.S. Department of Energy (DOE) Information Bridge: Web site: http://www.osti.gov/bridge Reports produced before January 1, 1996, may be purchased by members of the public from the following source: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-605-6000 (1-800-553-6847) TDD: 703-487-4639 Fax: 703-605-6900 E-mail: [email protected] Web site: http://www.ntis.gov/support/ordernowabout.htm Reports are available to DOE employees, DOE contractors, Energy Technology Data Exchange (ETDE) representatives, and International Nuclear Information System (INIS) representatives from the following source: Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831 Telephone: 865-576-8401 Fax: 865-576-5728 E-mail: [email protected] Web site: http://www.osti.gov/contact.html This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. This work was sponsored by the Office of Radiation and Indoor Air, U. S. Environmental Protection Agency, under Interagency Agreement DOE No. 1824-S581-A1, under contract DE-AC05-84OR21400 with UT-Battelle. ORNL/TM-2006/583 Uncertainties in Cancer Risk Coefficients for Environmental Exposure to Radionuclides An Uncertainty Analysis for Risk Coefficients Reported in Federal Guidance Report No. 13 Authors: D. J. Pawel R. W. Leggett K. F. Eckerman C. B. Nelson Date Published: January 2007 Published by OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37831 Managed by UT-Battelle, LLC for the U.S. DEPARTMENT OF ENERGY under contract DE-AC05-00OR227. ii PREFACE Federal Guidance Report No.13 (FGR 13) provides cancer risk coefficients for various modes of environmental exposure to each of more than 800 radionuclides (EPA 1999), including inhalation of airborne activity and ingestion of activity in food or drinking water. A risk coefficient for inhalation or ingestion of a radionuclide is an estimate of the probability of radiogenic cancer mortality or morbidity per unit activity taken into the body. A risk coefficient may be interpreted either as the average risk per unit intake for persons exposed throughout life to a constant activity concentration of a radionuclide, or as the average risk per unit intake for persons exposed briefly to the radionuclide in an environmental medium. The risk coefficients in FGR 13 apply to an average member of the public in the sense that estimates of risk are averaged over the age and gender distributions of a hypothetical population whose survival functions and cancer mortality rates are based on recent data for the U.S. Uncertainties in cancer mortality risk coefficients were assessed in FGR 13 for inhalation or ingestion of each of 11 radionuclides: 3H, 60Co, 90Sr, 106Ru, 125Sb, 131I, 137Cs, 226Ra, 232Th, 234U, and 239Pu. Assigned levels of uncertainty were based on sensitivity analyses in which various combinations of plausible biokinetic and dosimetric models and radiogenic cancer risk models were used to generate alternative risk coefficients. Uncertainties relating to the validity of the linear-no-threshold hypothesis were not addressed in the analysis because this is not feasible. Also, the analysis did not address uncertainties associated with absorbed dose as a measure of cancer risk. The present report updates the uncertainty analysis in FGR 13 for the cases of inhalation and ingestion of radionuclides and expands the analysis to all radionuclides addressed in that report. This analysis is in response to suggestions that the uncertainty analysis in FGR 13 should be expanded as an aid in determining the kinds of additional information that are most needed for improving confidence in risk assessments for exposure to environmental radionuclides. As in FGR 13, results of the uncertainty analysis are given in terms of semi-quantitative “uncertainty categories” identified by letters A-E, with Category A representing the most narrowly determined risk coefficients, Category E representing the least well characterized coefficients, and Categories B, C, and D representing intermediate, increasing levels of uncertainty. Assignment of a risk coefficient to an uncertainty category was based on propagation of uncertainties in components of a simplified version of the complex computational model used in FGR 13 to calculate risk coefficients. The uncertainty in a risk coefficient was viewed as the net result of uncertainties in the following main components of the derivation: biokinetic models describing the biological behavior of ingested or inhaled radionuclides; specific energies that relate emissions from source organs to energy deposition in target organs; risk model coefficients representing the risk of cancer per unit absorbed dose to sensitive tissues from low-LET radiation at high dose and high dose rate; tissue-specific dose and dose rate effectiveness factor (DDREF); and tissue-specific high-dose relative biological effectiveness (RBE). The biokinetic models and specific energies together make up the dose model, and the iii risk model coefficients, DDREF, and RBEs together make up the risk model. This formulation allows a convenient allocation of uncertainties associated with the models used to derive the risk coefficients. Peer reviewers of this report were Dr. Andre Bouville of the U.S. National Institutes of Health, Dr. Lawrence Miller of the Department of Nuclear Engineering, University of Tennessee, and Dr. Wilson McGinn of the Environmental Sciences Division, Oak Ridge National Laboratory (ORNL). Dr. Bouville has chaired or served as a member of a number of committees of the U.S. National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP) concerned with uncertainties in radiation dose or risk estimates. Dr. Miller has been involved in investigations of uncertainties in dose estimators for environmentally important radionuclides including 90Sr, 131I, and 137Cs. Dr. McGinn leads the Risk and Regulatory Analysis Group at ORNL and has experience in the area of uncertainties in risk estimators for chemical hazards. The main comments received from the peer reviewers are paraphrased below. Each comment is followed by a summary of related changes made in the report or reasons for not making changes. 1) The section titled “Results” is too general. Presentation of results for a few radionuclides would be helpful. Fifteen selected risk coefficients are now examined in Section 3 (Results), six for inhaled radionuclides and nine for ingested radionuclides. The main sources of uncertainty for each of these cases are summarized in a table. 2) The section titled “Discussion” should be expanded. This section was expanded to provide a fuller discussion of the strengths and weaknesses of the analytical approach. Issues related to characterization of uncertainties in radiogenic cancer risk models were addressed at length because these models are indicated by the analysis to be the dominant source of uncertainty in most of the risk coefficients for inhalation or ingestion given in FGR 13. 3) Explain why relatively large uncertainties were assigned to risk coefficients for the extensively studied radionuclide 131I while relatively small uncertainties were assigned to coefficients for some radionuclides such as 95Zr for which little information is available. Factors determining uncertainty categories for risk coefficients for 131I, 95Zr, and a number of other radionuclides representing different levels of information were examined and are now addressed in Section 3 (Results). Limitations of the methodology specific to the important radionuclide 131I are further addressed in Section 4 (Discussion). In response to this review comment and the subsequent critical reexamination of the analytical methods, the methodology was revised slightly and uncertainty categories were recalculated for all cases addressed in the report. Based on the revised methods, the uncertainty categories for ingestion of 131I and inhalation of soluble forms of 131I were both revised from Category D (accurate within a factor iv of 10) to Category C (accurate within a factor
Load more

Recommended publications
  • Spectroscopy of Neutron-Rich 34,35,36,37,38 P Populated In
    PHYSICAL REVIEW C 92, 044308 (2015) , , , , Spectroscopy of neutron-rich 34 35 36 37 38P populated in binary grazing reactions R. Chapman,1,* A. Hodsdon,1 M. Bouhelal,2 F. Haas,3 X. Liang,1 F. Azaiez,4 Z. M. Wang,1 B. R. Behera,5 M. Burns,1 E. Caurier,3 L. Corradi,5 D. Curien,3 A. N. Deacon,6 Zs. Dombradi,´ 7 E. Farnea,8 E. Fioretto,5 A. Gadea,5 F. Ibrahim,4 A. Jungclaus,9 K. Keyes,1 V. Kumar, 1 S. Lunardi,8 N. Marginean,˘ 5,10 G. Montagnoli,8 D. R. Napoli,5 F. Nowacki,3 J. Ollier,1,11 D. O’Donnell,1,12 A. Papenberg,1 G. Pollarolo,13 M.-D. Salsac,14 F. Scarlassara,8 J. F. Smith,1 K. M. Spohr,1 M. Stanoiu,10 A. M. Stefanini,5 S. Szilner,5,15 M. Trotta,5 and D. Verney4 1School of Engineering and Computing, University of the West of Scotland, Paisley PA1 2BE, United Kingdom, and The Scottish Universities Physics Alliance (SUPA) 2Laboratoire de Physique Appliquee´ et Theorique,´ Universite´ Larbi Tebessa,´ Tebessa,´ Algerie´ 3IPHC, UMR7178, CNRS-IN2P3, and Universite´ de Strasbourg, F-67037 Strasbourg Cedex 2, France 4IPN, IN2P3-CNRS and Universite´ Paris-Sud, F-91406 Orsay Cedex, France 5INFN, Laboratori Nazionali di Legnaro, I-35020 Legnaro, Padova, Italy 6Schuster Laboratory, University of Manchester, Manchester M13 9PL, United Kingdom 7MTA ATOMKI, P.O. Box 51, H-4001 Debrecen, Hungary 8Dipartimento di Fisica and INFN-Sezione di Padova, Universita` di Padova, I35131 Padova, Italy 9Instituto de Estructura de la Materia, CSIC, E-28006 Madrid, Spain 10Horia Hulubei National Institute of Physics and Nuclear Engineering-IFIN-HH, Strasse Atomistilor No.
    [Show full text]
  • Understanding Variation in Partition Coefficient, Kd, Values: Volume II
    United States Office of Air and Radiation EPA 402-R-99-004B Environmental Protection August 1999 Agency UNDERSTANDING VARIATION IN PARTITION COEFFICIENT, Kd, VALUES Volume II: Review of Geochemistry and Available Kd Values for Cadmium, Cesium, Chromium, Lead, Plutonium, Radon, Strontium, Thorium, Tritium (3H), and Uranium UNDERSTANDING VARIATION IN PARTITION COEFFICIENT, Kd, VALUES Volume II: Review of Geochemistry and Available Kd Values for Cadmium, Cesium, Chromium, Lead, Plutonium, Radon, Strontium, Thorium, Tritium (3H), and Uranium August 1999 A Cooperative Effort By: Office of Radiation and Indoor Air Office of Solid Waste and Emergency Response U.S. Environmental Protection Agency Washington, DC 20460 Office of Environmental Restoration U.S. Department of Energy Washington, DC 20585 NOTICE The following two-volume report is intended solely as guidance to EPA and other environmental professionals. This document does not constitute rulemaking by the Agency, and cannot be relied on to create a substantive or procedural right enforceable by any party in litigation with the United States. EPA may take action that is at variance with the information, policies, and procedures in this document and may change them at any time without public notice. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government. ii FOREWORD Understanding the long-term behavior of contaminants in the subsurface is becoming increasingly more important as the nation addresses groundwater contamination. Groundwater contamination is a national concern as about 50 percent of the United States population receives its drinking water from groundwater.
    [Show full text]
  • Experimental Γ Ray Spectroscopy and Investigations of Environmental Radioactivity
    Experimental γ Ray Spectroscopy and Investigations of Environmental Radioactivity BY RANDOLPH S. PETERSON 216 α Po 84 10.64h. 212 Pb 1- 415 82 0- 239 β- 01- 0 60.6m 212 1+ 1630 Bi 2+ 1513 83 α β- 2+ 787 304ns 0+ 0 212 α Po 84 Experimental γ Ray Spectroscopy and Investigations of Environmental Radioactivity Randolph S. Peterson Physics Department The University of the South Sewanee, Tennessee Published by Spectrum Techniques All Rights Reserved Copyright 1996 TABLE OF CONTENTS Page Introduction ....................................................................................................................4 Basic Gamma Spectroscopy 1. Energy Calibration ................................................................................................... 7 2. Gamma Spectra from Common Commercial Sources ........................................ 10 3. Detector Energy Resolution .................................................................................. 12 Interaction of Radiation with Matter 4. Compton Scattering............................................................................................... 14 5. Pair Production and Annihilation ........................................................................ 17 6. Absorption of Gammas by Materials ..................................................................... 19 7. X Rays ..................................................................................................................... 21 Radioactive Decay 8. Multichannel Scaling and Half-life .....................................................................
    [Show full text]
  • THE NATURAL RADIOACTIVITY of the BIOSPHERE (Prirodnaya Radioaktivnost' Iosfery)
    XA04N2887 INIS-XA-N--259 L.A. Pertsov TRANSLATED FROM RUSSIAN Published for the U.S. Atomic Energy Commission and the National Science Foundation, Washington, D.C. by the Israel Program for Scientific Translations L. A. PERTSOV THE NATURAL RADIOACTIVITY OF THE BIOSPHERE (Prirodnaya Radioaktivnost' iosfery) Atomizdat NMoskva 1964 Translated from Russian Israel Program for Scientific Translations Jerusalem 1967 18 02 AEC-tr- 6714 Published Pursuant to an Agreement with THE U. S. ATOMIC ENERGY COMMISSION and THE NATIONAL SCIENCE FOUNDATION, WASHINGTON, D. C. Copyright (D 1967 Israel Program for scientific Translations Ltd. IPST Cat. No. 1802 Translated and Edited by IPST Staff Printed in Jerusalem by S. Monison Available from the U.S. DEPARTMENT OF COMMERCE Clearinghouse for Federal Scientific and Technical Information Springfield, Va. 22151 VI/ Table of Contents Introduction .1..................... Bibliography ...................................... 5 Chapter 1. GENESIS OF THE NATURAL RADIOACTIVITY OF THE BIOSPHERE ......................... 6 § Some historical problems...................... 6 § 2. Formation of natural radioactive isotopes of the earth ..... 7 §3. Radioactive isotope creation by cosmic radiation. ....... 11 §4. Distribution of radioactive isotopes in the earth ........ 12 § 5. The spread of radioactive isotopes over the earth's surface. ................................. 16 § 6. The cycle of natural radioactive isotopes in the biosphere. ................................ 18 Bibliography ................ .................. 22 Chapter 2. PHYSICAL AND BIOCHEMICAL PROPERTIES OF NATURAL RADIOACTIVE ISOTOPES. ........... 24 § 1. The contribution of individual radioactive isotopes to the total radioactivity of the biosphere. ............... 24 § 2. Properties of radioactive isotopes not belonging to radio- active families . ............ I............ 27 § 3. Properties of radioactive isotopes of the radioactive families. ................................ 38 § 4. Properties of radioactive isotopes of rare-earth elements .
    [Show full text]
  • A Living Radon Reference Manual
    A LIVING RADON REFERENCE MANUAL Robert K. Lewis Pennsylvania Department of Environmental Protection Bureau of Radiation Protection, Radon Division and Paul N. Houle, PhD University Educational Services, Inc. Abstract This “living” manual is a compilation of facts, figures, tables and other information pertinent and useful to the radon practitioner, some of which can be otherwise difficult to find. It is envisioned as a useful addition to one’s desk and radon library. This reference manual is also intended to be a “living” document, where its users may supply additional information to the editors for incorporation in revisions as well as updates to this document on-line. Topics contained within the current version include radon chemistry and physics, radon units, radon fans, epidemiology, ambient radon, diagnostics, dosimetry, history, lung cancer, radon in workplace and radon statistics. In some cases motivations and explanations to the information are given. References are included. Introduction This reference manual is a compilation of facts, figures, tables and information on various aspects of radon science. It is hoped that this manual may prove useful to federal and state employees, groups such as AARST and CRCPD, and industry. There are numerous other reference manuals that have been produced on the various aspects of radon science; however, we hope that this manual will have a more “applied” use to all of the various radon practitioners who may use it. Many of the snippets on the various pages are highlights from referenced sources. The snippet will obviously only provide one with the briefest of information. To learn more about that item go to the reference and read the whole paper.
    [Show full text]
  • Mathematical Model of Radon Activity Measurements
    2015 International Nuclear Atlantic Conference - INAC 2015 São Paulo, SP, Brazil, October 4-9, 2015 ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-06-9 MATHEMATICAL MODEL OF RADON ACTIVITY MEASUREMENTS Sergei A. Paschuk1, Janine N. Corrêa1, Jaqueline Kappke1, Pedro Zambianchi1 and Valeriy Denyak2 1 Federal University of Technology - Paraná Av. Sete de Setembro, 3165 80230-901, Curitiba, PR [email protected], [email protected] 2 Pelé Pequeno Príncipe Research Institute, Av. Silva Jardim, 1632, Curitiba 80250-200, PR, Brazil [email protected] ABSTRACT Present work describes a mathematical model that quantifies the time dependent amount of 222Rn and 220Rn altogether and their activities within an ionization chamber as, for example, AlphaGUARD, which is used to measure activity concentration of Rn in soil gas. The differential equations take into account tree main processes, namely: the injection of Rn into the cavity of detector by the air pump including the effect of the traveling time Rn takes to reach the chamber; Rn release by the air exiting the chamber; and radioactive decay of Rn within the chamber. Developed code quantifies the activity of 222Rn and 220Rn isotopes separately. Following the standard methodology to measure Rn activity in soil gas, the air pump usually is turned off over a period of time in order to avoid the influx of Rn into the chamber. Since 220Rn has a short half-life time, approximately 56s, the model shows that after 7 minutes the activity concentration of this isotope is null. Consequently, the measured activity refers to 222Rn, only. Furthermore, the model also addresses the activity of 220Rn and 222Rn progeny, which being metals represent potential risk of ionization chamber contamination that could increase the background of further measurements.
    [Show full text]
  • Radiation Weighting Factors
    Sources of Radiation Exposure Sources of Radiation Exposure to the US Population (from U.S. NRC, Glossary: Exposure. [updated 21 July 2003, cited 26 March 2004] http://www.nrc.gov/reading-rm/basic-ref/glossary/exposure.html In the US, the annual estimated average effective dose to an adult is 3.60 mSv. Sources of exposure for the general public • Natural radiation of terrestrial origin • Natural radiation of cosmic origin • Natural internal radioisotopes • Medical radiation • Technologically enhanced natural radiation • Consumer products • Fallout • Nuclear power Other 1% Occupational 3% Fallout <0.3% Nuclear Fuel Cycle 0.1% Miscellaneous 0.1% Radioactivity in Nature Our world is radioactive and has been since it was created. Over 60 radionuclides can be found in nature, and they can be placed in three general categories: Primordial - been around since the creation of the Earth Singly-occurring Chain or series Cosmogenic - formed as a result of cosmic ray interactions Primordial radionuclides When the earth was first formed a relatively large number of isotopes would have been radioactive. Those with half-lives of less than about 108 years would by now have decayed into stable nuclides. The progeny or decay products of the long-lived radionuclides are also in this heading. Primordial nuclide examples Half-life Nuclide Natural Activity (years) Uranium 7.04 x 108 0.72 % of all natural uranium 235 Uranium 99.27 % of all natural uranium; 0.5 to 4.7 ppm total 4.47 x 109 238 uranium in the common rock types Thorium 1.6 to 20 ppm in the common
    [Show full text]
  • Radon in Icelandic Cold Groundwater and Low-Temperature Geothermal Water
    Available online at www.sciencedirect.com ScienceDirect Procedia Earth and Planetary Science 17 ( 2017 ) 229 – 232 15th Water-Rock Interaction International Symposium, WRI-15 Radon in Icelandic Cold Groundwater and Low-Temperature Geothermal Water Finnbogi Óskarssona,1, Ragnheiður St. Ásgeirsdóttira aIceland GeoSurvey (ISOR), Grensasvegur 9, IS-108 Reykjavik, Iceland Abstract Samples of hot and cold water for radon analysis were collected from boreholes and springs in Iceland in 2014 and 2015. The majority of the samples was collected from municipal district heating services or potable water utilities. The total number of samples was 142, covering most towns and villages in Iceland. Radon activity is generally rather low, in most cases less than 5 Bq/L. Only 12 samples had a measured radon activity higher than 5 Bq/L, with a maximum activity of 10.8 Bq/L. The hot water samples generally have a higher radon activity than cold water samples, but samples from boiling borholes have a lower radon activity as radon fractionates into the vapour phase. The geographical distribution of the samples indicates that radon activity is generally lower within the active rift zones. This is most likely due to the very low uranium content of the tholeiites typically erupted within the rift zones. Higher radon values (> 5 Bq/L) are in most cases close to extinct central volcanoes and thus it seems plausible that the water sampled has been in contact with felsic rocks. © 20172017 The The Authors. Authors. Published Published by Elsevierby Elsevier B.V. B.V. This is an open access article under the CC BY-NC-ND license Peer(http://creativecommons.org/licenses/by-nc-nd/4.0/-review under responsibility of the organizing).
    [Show full text]
  • Point Defects in Lithium Gallate and Gallium Oxide
    Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 8-23-2019 Point Defects in Lithium Gallate and Gallium Oxide Christopher A. Lenyk Follow this and additional works at: https://scholar.afit.edu/etd Part of the Nuclear Engineering Commons Recommended Citation Lenyk, Christopher A., "Point Defects in Lithium Gallate and Gallium Oxide" (2019). Theses and Dissertations. 2369. https://scholar.afit.edu/etd/2369 This Dissertation is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. POINT DEFECTS IN LITHIUM GALLATE AND GALLIUM OXIDE DISSERTATION Christopher A. Lenyk, Lt Col, USAF AFIT-ENP-DS-19-S-023 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. The views expressed in this document are those of the author and do not reflect the official policy or position of the United States Air Force, the United States Department of Defense or the United States Government. This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. AFIT-ENP-DS-19-S-023 POINT DEFECTS IN LITHIUM GALLATE AND GALLIUM OXIDE DISSERTATION Presented to the Faculty Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Nuclear Engineering Christopher A.
    [Show full text]
  • Z 221 PS2 Practice.Pages
    CH 221 Practice Problem Set #2 This is a practice problem set and not the actual graded problem set that you will turn in for credit. Answers to each problem can be found at the end of this assignment. Covering: Chapter Two, Chapter 3.1 and Chapter Guide Two Important Tables and/or Constants: 1 mol = 6.022 x 1023 ! 1. Give the mass number of each of the following atoms: a. magnesium with 15 neutrons, b. titanium with 26 neutrons, and c. zinc with 32 neutrons. A 2. Give the complete symbol ( ZX) for each of the following atoms: a. potassium with 20 neutrons, b. krypton with 48 neutrons, and c. cobalt with 33 neutrons. 3. Thallium has two stable isotopes, 203Tl and 205Tl. Knowing that the atomic weight of thallium is 204.4, which isotope€ is the more abundant of the two? 4. Silver (Ag) has two stable isotopes, 107Ag and 109Ag. The isotopic mass of 107Ag is 106.9051 and the isotopic mass of 109Ag is 108.9047. The atomic weight of Ag, from the periodic table, is 107.868. Estimate the percentage of 107Ag in a sample of the element. a. 0% b. 25% c. 50% d. 75% 5. Gallium has two naturally occurring isotopes, 69Ga and 71Ga, with masses of 68.9257 u and 70.9249 u, respectively. Calculate the percent abundances of these isotopes of gallium. 6. Calculate the mass in grams of: a. 2.5 mol aluminum b. 1.25 x 10-3 mol of iron c. 0.015 mol of calcium d.
    [Show full text]
  • Isotope Geochemistry of Gallium in Hydrothermal Systems
    ISOTOPE GEOCHEMISTRY OF GALLIUM IN HYDROTHERMAL SYSTEMS by Constance E. Payne A thesis submitted to Victoria University of Wellington in partial fulfilment of the requirements for the degree of Master of Science Victoria University of Wellington 2016 ABSTRACT Little is known about the isotope geochemistry of gallium in natural systems (Groot, 2009), with most information being limited to very early studies of gallium isotopes in extra-terrestrial samples (Aston, 1935; De Laeter, 1972; Inghram et al., 1948; Machlan et al., 1986). This study is designed as a reconnaissance for gallium isotope geochemistry in hydrothermal systems of New Zealand. Gallium has two stable isotopes, 69Ga and 71Ga, and only one oxidation state, Ga3+, in aqueous media (Kloo et al., 2002). This means that fractionation of gallium isotopes should not be effected by redox reactions. Therefore the physical processes that occur during phase changes of hydrothermal fluids (i.e. flashing of fluids to vapour phase and residual liquid phase) and mineralisation of hydrothermal precipitates (i.e. precipitation and ligand exchange) can be followed by studying the isotopes of gallium. A gallium anomaly is known to be associated with some hydrothermal processes as shown by the unusual, elevated concentrations (e.g. 290 ppm in sulfide samples of Waiotapu; this study) in several of the active geothermal systems in New Zealand. The gallium isotope system has not yet been investigated since the revolution of high precision isotopic ratio measurements by Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) and so a new analytical methodology needed to be established. Any isotopic analysis of multi-isotope elements must satisfy a number of requirements in order for results to be both reliable and meaningful.
    [Show full text]
  • ATOMS and ELEMENTS Chapter 2 and Chapter 3 (3.1) “Chapter 2 Part 1” Elements: the Building Blocks of Nature Atoms: the Smallest Pieces of an Element
    Page III-2a-1 / Chapter Two Part I Lecture Notes Atoms, Molecules and Ions ATOMS AND ELEMENTS Chapter 2 and Chapter 3 (3.1) “Chapter 2 Part 1” Elements: the building blocks of Nature Atoms: the smallest pieces of an element Atoms contain protons, Chemistry 221 neutrons and electrons Professor Michael Russell Protons and neutrons in the nucleus Last update: MAR 8/9/21 MAR Where Does Matter Come From? FROM THE Big Bang The universe is 13.77 billion years old Hydrogen and Helium important Also Carbon, Oxygen and Neon MAR MAR Early Models of the Atom - Empedocles & Aristotle Element Abundance (Cosmic) Empedocles’ theory of matter (later modified by Aristotle) with four Most abundant "elements" (coined by Plato) held C elements in the for approximately 2000 years! O Al Si Fe Earth's Element "mixtures" produce "properties" of hot, wet, etc. • Crust: Silicon and oxygen • Atmosphere: Plato Empedocles Aristotle nitrogen and oxygen MAR http://www.webelements.com/ MAR Page III-2a-1 / Chapter Two Part I Lecture Notes Page III-2a-2 / Chapter Two Part I Lecture Notes The "Newton" of Chemistry Early Models of the Atom - Democritus JOHN DALTON (1766 - 1844) DEMOCRITUS (460 - 370 BCE) 1804 - Proposed Atomic Theory was a contemporary of Plato "Atoms cannot be created or destroyed" "Atoms of one element are different from other Atoms have structure and volume element's atoms" - proposed relative scale of "Gold can be divided into atomic masses (now the amu) smaller pieces only so far before the pieces no longer "Chemical change involves bond breaking, retain
    [Show full text]