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Radionuclides handbook
R&D Technical Report P3-101/SP1b
www.environment-agency.gov.uk
www.environment-agency.gov.uk
The Environment Agency is the leading public body protecting and
improving the environment in England and Wales.
It’s our job to make sure that air, land and water are looked after by
everyone in today’s society, so that tomorrow’s generations inherit a
cleaner, healthier world.
Our work includes tackling flooding and pollution incidents, reducing
industry’s impacts on the environment, cleaning up rivers, coastal
waters and contaminated land, and improving wildlife habitats.
Published by:
Environment AgencyRio HouseWaterside Drive, Aztec WestAlmondsbury, Bristol BS32 4UDTel: 01454 624400 Fax: 01454 624409
ISBN : 1844321762© Environment Agency October 2003
All rights reserved. This document may be reproduced with
prior permission of the Environment Agency.
This report is printed on Revive Matt, a 75% recycled stock,
which is 100% post consumer waste and is totally chlorine free.
Water used is treated and in most cases returned to source in
better condition than removed.
Further copies of this report are available from: Environment Agency, Government Buildings,
Burghill Road, Westbury-on-Trym, Bristol BS10 6BF
Tel: 0117 914 2656 Fax: 0117 914 2673
Authors:M Kelly, M Thorne*
Dissemination status:Internal: Released to Regions
External: Public Domain
Statement of use:This report is a reference document, describing physical, chemi-
cal and biological behaviour of radionuclides in the environment.
It was produced to complement R&D project P3-101/1a, aimed
at assessing possible impact of ionising radiation from authorised
discharges on Natura 2000 sites.
Research contractor:Serco Assurance
424 Harwell, Didcot, Oxfordshire, OX11 0QJ
Tel: +44 (0)1235 433005 Fax: +44 (0)1235 436579
* In conjunction with Mike Thorne and Associates Limited
Environment Agency Project Manager:Irene Zinger
Environment Agency Radionuclides Handbook 1
The completion of Stage 2 of the Environment Agency’s Review of Consents process (as required under the
Habitats Regulations 1994) has resulted in a number of RSA93 authorisations requiring a detailed (Stage
3) assessment. This requires an understanding of the environmental transfer characteristics, biotic uptake
and radiological impact of a wide range of radionuclides. There is a need to draw together the relevant
information into a single source document as a wide range of Environment Agency and English Nature
staff will be involved in undertaking the Stage 3 assessments. This report addresses that requirement.
The report is split into two parts:
1. An introduction to radioactivity and its properties, along with some of the global characteristics of the
radionuclides considered in the Handbook
2. Detailed information for a number of radionuclides that may require consideration in the Stage 3
assessments.
The aim of Part 1 of the report is to provide a basic introduction to radioactivity and its properties in
order to set in context the more detailed information provided in Part 2. Part 1 briefly covers the
following:
• fundamental facts about atoms and the nature of radioactivity;
• how radiation interacts with matter and the implications for living organisms;
• the radionuclides considered and their inter-relationships;
• the general features described for each radionuclide in Part 2.
Part 2 provides information about 85 radionuclides, including:
• basic properties
• modes of decay
• chemical properties and analogues
• environmental transfer characteristics
• uptake by, and exposure of, biota
• dosimetric issues.
It is not intended to provide an exhaustive set of properties and characteristics in Part 2. Rather, the aim is
to provide a basic understanding for the environmental behaviour and radiological significance of the
radionuclides and their possible impact on non-human species.
A list of references is given at the end of Part 1, together with some suggestions for additional reading. To
help the reader, a substantial glossary is given at the end of the report.
Executive summary
Contents
Executive Summary 1
List of Tables and Figures 3
Introduction 4
Acknowledgements 4
Part 1 - Brief introduction to radioactivity and its properties 5
1. Introduction to atoms and radioactivity 6
2. Effects of radiation on matter and wildlife 12
3. Radionuclides considered 15
4. Radionuclide data detailed in Part 2 18
5. References 26
Part 2 - Information on each radionuclide - listed by symbol 28
Glossary 204
Environment Agency Radionuclides Handbook2
Environment Agency Radionuclides Handbook 3
List of Tables and Figures
Table 1: Selection of radionuclides for the Handbook 16
Table 2: Radionuclides analogues, listed by radionuclide symbol 21
Table 3: Behaviour of radionuclides, listed by radionuclide symbol 22
Figure 1: The periodic table (the first 103 elements) 8
Figure 2: The model of a helium atom 6
Figure 3: Radioactive decay of carbon-14 7
Figure 4: Types of beta decay 10
Figure 5: Example of a radioactive decay chain 11
Figure 6: Ionisation of the helium ion 12
Figure 7: Relative range of travel of alpha and beta particles 13
Figure 8: The cell 13
Figure 9: Origins of radionuclides 23
Figure 10: Main decay modes of radionuclides 24
Figure 11: Main uses of radionuclides 25
Figure 13: Decay mode graphs for strontium-90 19
Introduction
The wide range of staff involved in Stage 3 assessments will need to access basic information on theproperties of radionuclides to help them understand their impact in the environment. While this informationis available from a variety of sources, no single document details the properties and behaviour of the fullrange of relevant radionuclides in the environment. The aim of this Handbook is to address this and to bringbasic information regarding a number of important radionuclides together in a single reference.
The report is divided into two parts.
• Part 1 provides a basic introduction to radioactivity and its properties in order to set in context the moredetailed information provided in Part 2.
• The properties of 85 radionuclides that may be relevant to the radiation protection of wildlife arepresented in Part 2. The intention is not to provide an exhaustive set of properties and characteristics.Rather, the aim is to provide a basic understanding of the environmental behaviour and radiologicalsignificance of a number of radionuclides, and their possible impact on non-human species.
The glossary also includes entries from the glossary given in Environment Agency R&D Publication 128(Copplestone et al., 2001).
Environment Agency Radionuclides Handbook4
The completion of Stage 2 of the Environment Agency’s Review of
Consents process (as required under the Habitats Regulations
1994) has resulted in a number of Radioactive Substances Act
1993 (RSA93) authorisations requiring a full Appropriate
Assessment (Stage 3).
The report draws on work carried out by AEA Technology plc on the production of datasheets for a number ofradionuclides for the Environment Agency’s pollution inventory.
The report was also peer-reviewed by dedicated Agency staff and externally by staff at the University ofLiverpool to ensure that the technical content was accurate and reflected people’s experiences in this field.
Acknowledgements
PART 1Brief introduction to radioactivity and its properties
Fundamental concepts on atoms and the nature of radioactivity are
summarised in Section 1. Section 2 goes on to consider how
radiation interacts with matter and the possible implications for
living organisms, while Section 3 considers some of the general
features of the radionuclides covered in Part 2 of the report.
Section 4 describes the type of information given in Part 2 and
introduces its format. Section 5 lists the references cited in the
report and provides some suggestions for additional reading and a
short list of useful websites.
Environment Agency Radionuclides Handbook 5
Further information relating to radioactivity and its properties can be obtained from NRPB (1998).
Environment Agency Radionuclides Handbook6
1. Introduction to atoms andradioactivity
An atom consists of a nucleus, around which rotatesa number of electrons (Figure 2). The radius of theorbits of these electrons is about the same as theatomic size, i.e. 10-8 cm. The radius of the nucleus isabout 100,000 times smaller. Electrons carry anegative electrical charge, whereas the nucleuscarries a positive electrical charge.
The nucleus itself is composed of two types of smallerparticle, called protons and neutrons. These particleshave similar masses (the neutron is slightly heavier),but they differ in that the proton carries a positiveelectrical charge (equal in magnitude but opposite tothe electron). Protons and neutrons differ in otherways, but these are not relevant to this discussion.
Proton
Neutron
Electron
In a simplified model of the atom, electrons rotate around
a nucleus consisting of protons and neutrons. The
diagram above shows a helium atom.
All matter is made up from atoms; an atom is the smallest particle
that has the physical characteristics of any given element. Atoms
are very small - the diameter of the smallest atoms is about 10-8
cm. About 114 different species of atom have so far been
discovered. Each species of atom defines an element such as
oxygen, helium and carbon. Figure 1 shows the first 103 elements
in the form of the periodic table.
The 114 or so elements are identified in terms of thenumber of protons in the nucleus. Elements with lowatomic number are often referred to as light elementsand those with high atomic number are referred to asheavy elements. The lightest element (hydrogen) hasonly a single proton, whereas the heaviest has 114protons. Hydrogen has only a single electron rotatingaround its nucleus, whereas the heaviest has 114electrons. Each element has:
• an atomic number, Z, i.e. the number of protonsin the nucleus;
• a neutron number, N, i.e. the number of neutronsin the nucleus;
• an atomic mass, A, which is the total number ofprotons plus neutrons.
The vertical columns of the periodic table are referredto as ‘groups’; the elements within a group tend tohave similar chemical properties. Thus, for example,sodium (Z = 11) and potassium (Z = 19) both belongto Group 1 and have similar chemical properties.The environmental characteristics of an element forwhich data are scarce can often be inferred byconsidering the properties of other better-understoodelements in the same group. For further information,see Hill and Holman (2000).
Figure 2: Model of a helium atom
1
Radioactivity may be defined as a spontaneousnuclear transformation that usually results in theformation of a different nucleus and occurs when thenucleus is moving to a more stable situation byemitting energy or particles. The transformation fromone nucleus to another nucleus is called radioactivedecay (see the example in Figure 3). Consider anucleus with Z protons and N (equals A - Z)neutrons. The nucleus can only be stable for certaincombinations of Z and N. By ‘stable’, we mean thatthe nucleus remains in the same form (with the sameZ and N) for an infinite period of time. N is generallygreater than Z, but nuclei with more protons thatneutrons can occur, e.g. helium-3 has two protonsand one neutron.
Figure 3: Radioactive decay of carbon-14
The antineutrino (as illustrated in the decay ofcarbon-14 in Figure 3) has a negligible mass andcarries no charge, and consequently is of littlerelevance from the perspective of radiationprotection. It is not considered further in this report.
As another example, stable cobalt has an atom with27 protons and 32 neutrons (Z = 27, A = 59), andmay be written as cobalt-59, or, more technically, as 59Co. However, if the nucleus gains an extraneutron compared with stable cobalt-59, then a newnucleus with Z = 27, A = 60 is formed that isunstable. This is known as cobalt-60 (abbreviated asCo-60), which is said to be radioactive.
The cobalt-60 nucleus is not stable and can onlyexist in that form for a limited amount of time. Thenucleus eventually changes its form to aconfiguration that is stable; this involves a change inthe numbers of protons and neutrons present. Inthis case, one of the neutrons becomes a proton andan electron is emitted from the nucleus. Asexplained later, this electron is called a beta particle.Atoms with nuclei that have the same number ofprotons but differing number of neutrons are calledisotopes. These atoms thus belong to the sameelement and isotopes of an element have essentially
the same chemical properties.
Half-lifeIt is not possible to predict the exact amount of timethat will elapse before any particular unstable nucleusdecays. However, if a large number of such nucleiare present, one can define an average decay time.This is related to an important quantity known as theradioactive half-life. This is defined as the timerequired for half of the nuclei present to decay. Inthe case of cobalt-60, the radioactive half-life isabout 5 years; that is, after about 5 years, we canexpect approximately 500 cobalt-60 atoms to be leftfrom 1,000 cobalt-60 atoms.
The existence and decay of atoms with unstablenuclei is the basis for the existence of radiation andradioactivity. In the example of cobalt-60, theradioactive transformation of the nucleus to a morestable form is accompanied by the emission of anelectron, as one the neutrons in the nucleustransforms itself into a proton. In the case of cobalt-60, this transformation is also accompanied by theemission of a photon of electromagnetic radiation(called a gamma ray). It is the ultimate fate of thesegamma rays and the emitted electron that is ofconcern when considering the radioactive problemsposed by cobalt-60 (cobalt-60 sources are often usedin medical applications of radioactivity). This isdiscussed further in Section 2.
Radionuclide half-lives can vary from very small (forexample, polonium-214 has a half-life of 0.00016seconds) to very large (for example, thorium-232 hasa half-life of 1.4 x 1010 years). In many cases, short-lived radionuclides are only of limited importancewhen released into the environment. This is becausethey will decay before they can be transportedthrough the environment to locations where biotaare exposed to them.
Environment Agency Radionuclides Handbook 7
+ + Antineutrino
This neutron has been converted
to a proton
The decay of carbon-14. This isotope has an excess of neutrons
and hence is unstable. It decays by converting a neutron into a
proton, with the emission of an electron and an antineutrino.
Environment Agency Radionuclides Handbook8
HH
yd
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n
1 –
1.0
08
Li
Lith
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3 –
6.9
41
Na
So
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11
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19
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9.1
Rb
Ru
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37
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Cs
Ca
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55
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Fr
Fra
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Be
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Mg
Ma
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Ca
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Ba
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Lr
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Ce
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Nd
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Np
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Sm
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94
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Eu
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52
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Am
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95
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96
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Tb
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58
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97
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62
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Ho
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64
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Er
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68
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67
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Fm
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7
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Th
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69
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68
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Md
Me
nd
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10
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70
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Actin
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1A
2IIA
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3
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3B
4
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6
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7
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9
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10
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Alk
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Rare
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Ab
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ss
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mb
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Figure 1: The p
eriodic tab
le (the first 103 elements)
Modes of decayThe most common modes of radioactive decay are:
• alpha decay• beta decay• gamma emission as isomeric transformation (IT)• X-ray emission, e.g. electron capture (EC)• neutron.
Each of these modes of decay is explained below.
Alpha decay (α)Alpha decay is a type of radioactive decay in whichthe nucleus emits an alpha particle - a particle thatconsists of two protons and two neutrons boundtogether. An alpha particle is in fact a heliumnucleus. The alpha particle is emitted with anenergy that is characteristic of the nucleusundergoing the decay.
Plutonium-239 is an example of a radionuclide thatundergoes alpha decay. The alpha decay ofplutonium-239 can be written as follows:
239 235 4
94 Plutonimum → 92 Uranium + 2 Helium
With a few exceptions, alpha decay is only observedin nuclei with more than 82 protons.
Alpha decay is of greatest radiological importance forinternally incorporated radionuclides.
Beta decay (β)• Beta decay is the emission of electrons. They are
most commonly negatively charged (written asβ-), but are sometime positively charged, whenthey are called positrons (written as β+). In thistype of decay either a neutron is converted to aproton and the nucleus emits an electron, forexample:
131 131
53 Iodine → 54 Xenon + β- or
• a proton is converted into a neutron and thenucleus emits a positron (a positively chargedelectron), for example:
22 22
11 Sodium → 10 Neon + β+
The positron produced in the decay of sodium-22interacts with an electron and both ‘destroy’, givingrise to two gamma rays (each of energy 0.511 MeV).
In contrast to alpha decay, the energy of the emittedbeta particle can assume any value from zero up to amaximum value. Calculations of beta doses forradiation protection generally use the average energyof emission, which is about a third of the maximumvalue. Beta decay is often accompanied by theemission of one or more gamma rays.
Beta decay is of radiological importance for internallyincorporated radionuclides and external irradiation.
Gamma decay (γ)Gamma rays are pulses of electromagnetic radiation(called photons) that are emitted when the nucleusundergoes an internal rearrangement of itsconstituent protons and neutrons. The energy of thegamma ray is equal to the energy difference betweenthe initial and final (lower) energy states of thenucleus, and the emission is required to conserveenergy. Radiowaves, microwaves and visible light aremore familiar examples of electromagnetic radiation.
Usually, a gamma ray is emitted following beta decay(and occasionally alpha decay). Once the decay hasoccurred, the resultant nucleus is left in one of itshigher energy states. It moves back down to itslowest energy state by emitting one or more gammarays.
As illustrated in Figure 4, two types of beta decay areoften considered in radiation protection, as not allbeta emitters emit a gamma ray:
• pure beta emitters emit beta particle only, e.g.hydrogen-3;
• beta-gamma emitters emit beta particles andgamma rays, e.g. cobalt-60.
Environment Agency Radionuclides Handbook 9
Environment Agency Radionuclides Handbook10
Figure 4: Types of beta decay
In many cases, the gamma rays are of greaterradiological significance. Thus, cobalt-60 decays bybeta decay, but the gamma rays are the mostimportant when assessing the radiologicalconsequences of cobalt-60.
Another important class of radionuclides is those thatbeta decay to a metastable radionuclide (see belowunder isomeric transformation), which in turn emits agamma ray when it decays. An example is caesium-137, which beta decays to barium-137m (an excitedstate of barium-137), which in turn emits a gammaray as it decays to stable barium-137. In 89 % ofsubsequent decays of barium-137m, excess energy islost by emitting a gamma ray and, in the remaining11 % of cases, by internal conversion (see belowunder X-ray emission). Once again, it is the gammaray emitted by barium-137m that is of greatersignificance than the beta particle emitted bycaesium-137.
Gamma rays can be emitted without any previousalpha or beta decays by certain metastable speciessuch as Tc-99m and In-113m. These emit gammarays when they decay from their excited states to theground state via an isomeric transformation of thenucleus.
Gamma decay is of greatest radiological importancein the context of external irradiation. For largerspecies, however, internally incorporated gammaemitters are also important.
Isomeric transformation (IT)The release of gamma radiation from alpha or betadecay is sometimes delayed and the daughternucleus survives in a higher energy state (themetastable state) for some time before it returns to alower energy state by emitting gamma rays. Thisform of decay is called an isomeric transformationand the metastable state is denoted by the letter ‘m’
after the atomic mass, for example, technetium-99m.Technetium-99m decays to technetium-99 via anisomeric transformation, emitting a gamma ray as itdoes so.
X-ray emissionX-ray emission arises during a type of radioactivedecay known as internal conversion. Instead ofshedding its excess energy by emitting a gamma ray,an excited nucleus can dispose of its excess energyby interacting with one of the inner electronsorbiting the nucleus. This electron in turn absorbsthe excess energy and is ejected from the atom.When internal conversion occurs, other orbitingelectrons can ‘fall’ into the orbit vacated by theejected electron. When this happens, the electronloses energy, and an X-ray is emitted.
Orbital electron capture (EC) is another process thatproduces X-rays. Here, the nucleus captures one ofthe electrons orbiting the nucleus. As above, X-raysare emitted as the orbiting electrons rearrangethemselves to fill the orbit vacated. The electroninteracts with one of the protons to produce aneutron and a neutrino is ejected from the nucleus.The neutrino, however, has no radiologicalsignificance. Sodium-22 can decay by orbitalelectron capture, as well as by positron emission.
An outer electron falls into the vacancy left by thecaptured electron and an X-ray is emitted.
NeutronsNeutrons are usually produced in a laboratory ornuclear reactor when a nuclear transformation isinduced, for example, by taking an atom and firinganother nuclear particle at it, or when radioactivefission occurs. Fission is the breaking up of a largeunstable nucleus into two roughly equal nuclei, eacharound half the size of the original; this processliberates considerable amounts of energy. Theeffects of neutrons will not be considered further inthe context of environmental radioactivity.
The modes of radioactive decay discussed above leadto the production of new nuclides from the original.In some cases, the new nuclide will be stable.However, successive decays can lead to newradioactive species. In such cases, radioactive decaychains are formed. Figure 5 shows the decay chainfor uranium-238.
Nuclear
energy
levels
Nuclear
energy
levels
(lowest) (lowest) Emitted
gamma
ray
Pure beta decay Beta-gamma decay
++
In pure beta decay, the resultant nucleus is in its ground state.
In beta-gamma decay, the resultant nucleus is in an excited
state, and returns to the ground state by emitting a gamma ray.
Environment Agency Radionuclides Handbook 11
Uranium-238
4.468 109 years
Thorium-234
24.1 days
Protactinium-234m
1.17 minutes
Uranium-234
2.45 105 years
Thorium-230
77000 years
Radium-226
1600 years
Radon-222
3.8 days
Polonium-218
3.05 minutes
Lead-214
26.8 minutes
Bismuth-214
19.9 minutes
Polonium-214
1.6 10-5 seconds
Polonium-210
138 days
Bismuth-210
5.01 days
Lead-210
22.3 years
Lead-206
stable
Alpha decay
Beta decay
Beta decay
Alpha decay
Alpha decay
Alpha decay
Alpha decay
Alpha decay
Beta decay
Beta decay
Alpha decay
Beta decay
Beta decay
Alpha decay
Figure 5: Example of a radioactive decay chain (decay data from ICRP Publication 38)
Environment Agency Radionuclides Handbook12
To appreciate why these types of radiation arepotentially damaging to living entities, it is necessaryto understand how they interact with matter and, inparticular, living tissue and cells. It should be bornein mind that, just like all other matter, living tissueconsists of a collection of atoms and moleculesbound together to form the tissue mass. As before,further information relating to the effects of radiationon matter can be obtained from NRPB (1998).
Alpha and beta particlesAlpha and beta particles (and other chargedparticles) are often referred to as directly ionisingradiation. This is because, when an alpha or betaparticle enters living tissue, it interacts directly withthe outer electrons of the constituent atoms and, if itsupplies enough energy, it can knock the outerelectrons away from the atoms. The end products ofsuch an event are a free electron and a positivelycharged ion. This process is called ionisation (seeFigure 6) and is the basic physical mechanism thatgives rise to radiological detriment and harm.
Because alpha and beta particles have substantiallydifferent masses and different charges, the rates atwhich the two types of particle cause ionisation arevery different:
• beta particle produces >100 ionisation events percm of travel;
• alpha particle produces >10,000 ionisation eventsper cm of travel.
Alpha particles therefore cause considerably moreionisations (and hence radiological damage).However, as shown in Figure 7, this is partly offset bythe fact that alpha particles have a very much smallerrange of travel in body tissue than beta particles ofthe same energy (of the order of micrometrescompared with centimetres for beta particles). Asthe energy of either particle increases, so the rangeincreases.
Figure 6: Example of the ionisation of an atom
The previous section described how radioactive decay can lead to
the following by-products:
• alpha particles (helium nuclei)
• beta particles (electrons or positrons)
• gamma rays (high energy electromagnetic radiation)
• X-rays.
2. Effects of radiation on matter andwildlife
Ionisation of the helium atom. The helium ion on the
right has lost an electron, compared with the neutral
helium atom on the left.
2
Figure 7: Relative range of travel of alpha and betaparticles
A consequence of this is that alpha-emittingradioisotopes rarely pose a radiological hazard outsidethe body, as the alpha particles are not able topenetrate through skin. When alpha particles aretaken into the body, for example by inhalation intothe lung, the radiological hazard is high due to thevery high rate of ionisation as they slow down in lungtissue.
Gamma raysIn contrast to alpha and beta particles, gamma raysinduce ionisation in the atoms of living tissue byindirect means (the result of indirect ionisingradiation). There are three principal mechanisms bywhich gamma rays interact with living tissue:
• Compton scattering• photoelectric effect• pair production.
In the Compton effect, the gamma rays are scatteredfrom the outer electrons of the atoms, transferringenergy to the electrons and in the process reducingthe energy of the gamma ray. If enough energy issupplied during scattering, the outer electron will beremoved from the atom, leaving an ion and giving riseto a free electron.
The photoelectric effect and pair productionmechanisms are important for low and high gammaenergies, respectively. For the gamma rays emitted bythe majority of radionuclides, this can pose anenvironmental hazard. Compton scattering is the mostimportant interaction mechanism.
Microscopic effects of radiationTo understand the nature of the damage caused byradiation, it is necessary to look at the microscopicstructure of living organisms. Any living animal orplant is composed of a large number of individual cells(see Figure 8). These cells can be split broadly intotwo categories, namely somaticm cells and germ cells.
Germ cells are responsible for the reproduction ofoffspring and constitute the sperm in males and theova in females. All other cells fall under theclassification of somatic cells.
Figure 8: The cell
The genetic information that characterises anyindividual is contained within the chromosomes. Indogs, for example, the somatic cells contain 78chromosomes (39 chromosomes occurring in pairs)and germ cells contain 39 chromosomes (39chromosomes occurring once), so that when a spermand an ovum come together they produce acomposite with the full 78 chromosomes. All cells inthe body contain exactly the same geneticinformation; when cells divide, the chromosomes arereproduced exactly so that the new cells resultingfrom cellular division contain exactly the samegenetic information as in the original cell.
Suppose that a collection of cells in a living organismis subject to the types of radiation described above.The main effect of this radiation is to cause ionisationof the atoms in the absorbing medium. Thus, whencells are irradiated, it is likely that ionisation of one ormore of the atoms on some of the DNA moleculeswill occur. This can lead to a number ofconsequences for the affected molecule. Theseeffects include:
• breakage of the chains of molecules comprisingthe DNA;
• breakage of the links between chains.
In many cases, the cell is able to repair the damage,but not always. For example, single-strand breakswithin DNA can often be repaired without error,whereas double-strand breaks cannot. When thedamage cannot be repaired, the affected cell is left
Environment Agency Radionuclides Handbook 13
Beta
Alpha particles and beta particles show different behaviour when interacting
with matter. Alphas, on account of their mass, tend to follow straight paths,
whereas the much lighter beta particles tend to follow more random paths.
Beta particles can travel
up to 0.1 m
Alpha
Beta
Alpha particles only travel
around 0.000001 m
Beta particles can travel
up to 0.1 m
The chromosomes are composed largely of
DNA, and consist of linear sequences of genes
The cell nucleus, which
contains, among other
things, the chromosomes
The nucleolus, whose
primary role is ribosome
manufacture
Ribosomes, which are particles made up from
RNA and protein molecules, and which are the
sites for protein synthesis. Proteins are
fundamental to the structure of all organisms.
The cytoplasm. Contains the other living
contents of the cell, and provides the pathway
through which they communicate with each
other.
The cell. The above is a very simplified picture of a typical cell in animals and
humans. The characteristics (e.g. hair colour, blood group) of an individual is
determined by thecomposition of the genes, from which the chromosomes are
composed. DNA forms a “chemical” template for protein synthesis, which in
The cytoplasm. Contains the other living
contents of the cell, and provides the pathway
through which they communicate with each
other.
The cell. The above is a very simplified picture of a typical cell in animals and
humans. The characteristics (e.g. hair colour, blood group) of an individual is
determined by thecomposition of the genes, from which the chromosomes are
composed. DNA forms a “chemical” template for protein synthesis, which in
The nucleolus, whose
primary role is ribosome
manufacture
The cell nucleus, which
contains, among other
things, the chromosomes
Ribosomes, which are particles made up from
RNA and protein molecules, and which are the
sites for protein synthesis. Proteins are
fundamental to the structure of all organisms.
The chromosomes are composed largely of
DNA, and consist of linear sequences of genes
turn is mediated by RNA.
Environment Agency Radionuclides Handbook14
with altered or damaged genetic informationcompared with the unaffected cells. All descendantsof that cell will also contain altered or damagedinformation because cellular division results in exactreplication of the genetic information in the originalcell.
The multiplication of damaged cells in this way is thebasis for the induction of cancer in mammals.However, in the context of wildlife populations, anumber of alternative endpoints have been identifiedthat can be studied after exposure to radiation.These include:
• morbidity, e.g. illness and lifetime shortening;• mortality;• changes in reproductive capacity (including
fertility and fecundity);• mutation.
UNSCEAR (1996) provides a useful review of studiesrelating to the effects of ionising radiation on non-human species. UNSCEAR (1996) concluded that,overall, the general capacity of plant communities towithstand general stresses and changes within theenvironment also enables them to withstand low tomoderate radiation stress. There may be alterationsto community structure and morphological changesto individual plants (depending on the level ofradiation exposure), but the compensations aregenerally such as to maintain a normal energybalance.
Changes in animal communities in terrestrialenvironments seem mainly to arise indirectly as aconsequence of changes to the plant community.When plant species die in highly irradiated areas, thefood supplies of herbivorous animals and theirpredators are reduced. These animals may disappearand be replaced by species that depend on dead anddecaying material. Some of these species mayfurther damage remaining vegetation, which mightotherwise have survived.
Because of the compensation and adjustmentpossible in animal species, UNSCEAR (1996)considered it unlikely that radiation exposurescausing only minor effects in the most exposedindividual would have significant effects on thepopulation. Similar views are expressed in respect toaquatic communities.
Studies and interpretation of the effects of radiationon non-human species are ongoing. One example isthe EC 5th Framework Programme project, FASSET(Framework for ASSessment of EnvironmentalimpacT). A recent output from this project is areport by Woodhead and Zinger (2003) on radiationeffects to plants and animals.
3. Radionuclides considered
The selection of radionuclides originate from:
• the Environment Agency’s knowledge ofradionuclides present in regulatoryauthorisations;
• those identified by FASSET (Strand et al., 2001);• those used in assessment spreadsheets contained
in Agency guidance on implementing theHabitats Regulations 1994 (Allott and Dunn,2001).
Table 1 lists the chosen radionuclides detailed in Part 2. For a few elements, some radionuclides areproduced under two forms, for example, Tc-99 andTc-99m. The ‘m’ stands for ‘metastable’ (see Section 2). The Tc-99m nucleus has the samestructure as the Tc-99 nucleus, but exists in a higherenergy state and can remain there for a reasonablylong period of time. It decays to Tc-99 by emitting agamma ray.
More detailed information for these radionuclides isprovided in Part 2 in the form of two-pagesummaries of their key properties and characteristics,catalogued by radionuclide symbol, for example, Au-98 and Cs-137 (and not element name). Thepurpose of the Handbook is not to provide anexhaustive set of properties and characteristics for allradionuclides. The aim is rather to provide an insightinto the environmental behaviour and radiologicalsignificance of the radionuclides for non-humanspecies.
The use of numerical parameters has been avoidedwhere possible, although in some cases order-of-magnitude estimates of transfer parameters havebeen given to provide an indication of radionuclidesand species that are assimilated with particularefficiency into biological systems.
At the beginning of Part 2, radionuclides are listed bytheir symbols (e.g. Cs-137) and an index is givenwhich points to their location in the Handbook.
For this study, 85 radionuclides of possible environmental
significance to wildlife have been considered. Many of these
radionuclides originate from medical or industrial applications, or
are by-products of nuclear power generation. Total alpha emitters,
total beta emitters and depleted uranium are also considered.
Environment Agency Radionuclides Handbook 15
3
Environment Agency Radionuclides Handbook16
Element Radionuclide Symbol Origin of selectionAmericium Americium-241 Am-241 FASSET, Pub128Antimony Antimony-125 Sb-125 AgencyArgon Argon-41 Ar-41 Pub128Bromine Bromine-82 Br-82 AgencyCaesium Caesium-134 Cs-134 FASSET
Caesium-135 Cs-135 FASSETCaesium-137 Cs-137 FASSET, Pub128
Calcium Calcium-45 Ca-45 AgencyCalcium-47 Ca-47 Agency
Carbon Carbon-11 C-11 AgencyCarbon-14 C-14 FASSET, Pub128
Cerium Cerium-144 Ce-144 AgencyChlorine Chlorine-36 Cl-36 FASSET, AgencyChromium Chromium-51 Cr-51 AgencyCobalt Cobalt-57 Co-57 Agency
Cobalt-58 Co-58 AgencyCobalt-60 Co-60 Pub128
Curium Curium-242 Cm-242 FASSETCurium-243 Cm-243 FASSETCurium-244 Cm-244 FASSET
Erbium Erbium-169 Er-169 AgencyFluorine Fluorine-18 F-18 AgencyGallium Gallium-67 Ga-67 AgencyGold Gold-198 Au-198 AgencyIndium Indium-111 In-111 Agency
Indium-113m In-113m AgencyIodine Iodine-123 I-123 Agency
Iodine-125 I-125 Pub128Iodine-129 I-129 FASSET, Pub128Iodine-131 I-131 FASSET, Pub128
Iron Iron-59 Fe-59 AgencyKrypton Krypton-79 Kr-79 Agency
Krypton-81 Kr-81 AgencyKrypton-85 Kr-85 Pub128
Lanthanum Lanthanum-140 La-140 AgencyLead Lead-210 Pb-210 FASSETManganese Manganese-54 Mn-54 Agency
Manganese-56 Mn-56 AgencyMolybdenum Molybdenum-99 Mo-99 AgencyNeptunium Neptunium-237 Np-237 FASSETNickel Nickel-59 Ni-59 FASSET
Nickel-63 Ni-63 FASSETNiobium Niobium-94 Nb-94 FASSET
Niobium-95 Nb-95 Agency
Agency = Environment AgencyPub128 = R&D Publication 128N/A = not applicable
FASSET = Framework for ASSessment ofEnvironmental ImpacT (EC 5th Framework project)
Table 1 Selection of radionuclides for the Handbook
Environment Agency Radionuclides Handbook 17
Element Radionuclide Symbol Origin of selectionOxygen Oxygen-15 O-15 AgencyPhosphorus Phosphorus-32 P-32 Pub128
Phosphorus-33 P-33 AgencyPlutonium Plutonium-238 Pu-238 FASSET
Plutonium-239 Pu-239 FASSET, Pub128Plutonium-240 Pu-240 FASSETPlutonium-241 Pu-241 FASSET
Polonium Polonium-210 Po-210 FASSET, Pub128Potassium Potassium-40 K-40 FASSETPromethium Promethium-147 Pm-147 AgencyProtactinium Protactinium-234m Pa-234m AgencyRadium Radium-226 Ra-226 FASSET, Pub128Radon Radon-222 Rn-222 AgencyRhenium Rhenium-186 Re-186 AgencyRubidium Rubidium-81 Rb-81 Agency
Rubidium-86 Rb-86 AgencyRuthenium Ruthenium-106 Ru-106 FASSET, Pub128Samarium Samarium-153 Sm-153 AgencySelenium Selenium-75 Se-75 AgencySodium Sodium-22 Na-22 Agency
Sodium-24 Na-24 AgencyStrontium Strontium-89 Sr-89 FASSET, Pub128
Strontium-90 Sr-90 FASSET, Pub128Sulphur Sulphur-35 S-35 Pub128Technetium Technetium-99 Tc-99 FASSET, Pub128
Technetium-99m Tc-99m AgencyThallium Thallium-201 Tl-201 AgencyThorium Thorium-227 Th-227 FASSET
Thorium-228 Th-228 FASSETThorium-230 Th-230 FASSETThorium-231 Th-231 FASSETThorium-232 Th-232 FASSETThorium-234 Th-234 Pub128
Total alphas N/A N/A AgencyTotal Betas N/A N/A AgencyTritium Tritium H-3 FASSET, Pub128Uranium Uranium-234 U-234 FASSET
Uranium-235 U-235 FASSETUranium-238 U-238 FASSET, Pub128Depleted uranium N/A Agency
Vanadium Vanadium-48 V-48 AgencyXenon Xenon-133 Xe-133 AgencyYttrium Yttrium-90 Y-90 AgencyZirconium Zirconium-95 Zr-95 Agency
Agency = Environment AgencyPub128 = R&D Publication 128N/A = not applicable
FASSET = Framework for ASSessment ofEnvironmental ImpacT (EC 5th Framework project)
Table 1 continued
Environment Agency Radionuclides Handbook18
4. Radionuclide data detailed in Part 2
Basic information is supplied on the physical, chemical,
environmental and dosimetric behaviour of some 85 radionuclide.
The Handbook is set out in alphabetical order of thesymbol for each radionuclide (e.g. Ga-67 and In-111)rather than the name of the element. Table 1 can beused to identify the correct radionuclides, based ontheir element.
For ease of reference, the page layout for eachradionuclide is identical. Each part of the template isexplained below.
NameThe name of the element of which the radionuclideis an isotope and its mass number.
SymbolThe usual symbol for the radionuclide
OriginA classification to indicate how the radionuclide isproduced or arises. Where more than one of theseapplies to a radionuclide, the principal mode oforigin is listed. There are six possible choices (seeFigure 9 and Part 2).
• Activation. The process in which non-radioactiveelements are converted to radioactive elementsas a result of exposure to radiation in a nuclearreactor or weapon explosion. An example is theformation of techetium-99m for medicalpurposes from the irradiation of molydenum-99.
• Breeding. The production of one radionuclidefrom another due to the action of incidentatomic particles. An example is the productionof plutonium-239 from uranium-238.
• Cosmogenic. These are radionuclides producedin the upper atmosphere due to the action ofcosmic rays.
• Fission. A nuclear reaction in which an atom oflarge atomic mass splits into two atoms ofsmaller mass, with the production of one ormore neutrons and the release of energy.
• Primordial. These are radionuclides left overfrom the creation of the universe. Theynecessarily have very long half-lives, for example,uranium-238 and thorium-232.
• Radiogenic. A term applied to radionuclides thatarise from the decay of other radionuclides.
Radioactive half-lifeThe half-life of the radionuclide
Principle decay modeThe principal mode of radioactive decay for theradionuclide as described in Section 2. Figure 10shows the allocation of the investigated radionuclidesinto the four groups referred to in Part 2. The fourgroups are as follows.
• Alpha. Nuclear particles consisting of fast-moving helium nuclei (atomic mass of 4 andatomic number 2).
• Beta. A negatively charged (electron) orpositively charged (positron) particle emittedfrom the nucleus of an atom during radioactivedecay.
• X-ray as orbital electron capture (EC). A form ofradioactive decay in which the nucleus capturesan orbiting electron, converting a proton to a
Name
Symbol
Origin
Radioactive half-life
Principal decay mode
Grouping
4
neutron. The energy is released as gamma or X-rays.
• Gamma as isomeric transformation (IT). Verypenetrating electromagnetic radiation frequentlyemitted from the nucleus of an atom duringradioactive decay. IT is a form of radioactivedecay in which a metastable nucleus decays withthe release of energy as gamma rays.
For some radionuclides, the principal decay mode isnot the one of greatest significance from a radiationprotection perspective. For example, in the decay ofcobalt-60, the gamma rays emitted are of greaterimportance than the beta particle. Where this is thecase, the most radiologically significant emissions aregiven in square brackets.
GroupingAn indication of whether the radionuclide arisesnaturally in the environment or by artificial means(for example, in a nuclear reactor). The options forthis box are ‘natural’ or ‘artificial’.
ParentThe radionuclide(s) whose decay would give rise tothe radionuclide. This entry is set to ‘N/A’ if theparent is not produced naturally or artificially insignificant quantities.
DaughterThe nuclide that arises from decay of theradionuclide; it may be radioactive or stable. Wherethe daughter is itself radioactive, it is followed by acapital R in square brackets, i.e. [R].
DetectionAn indication of whether the radionuclide can bedetected ‘in the field’ or whether laboratory analysisis required. The options are ‘in situ’ and ‘laboratory’.As a general rule, strong gamma emitters can bedetected easily in situ, or even by aerial monitoringwith a fixed-wing aircraft. Radionuclides that onlyhave weak or zero gamma emissions usually have tobe identified from sample analysis in a laboratory(alpha and beta particles have limited ranges in air).
Production, uses and modes of release Figure 11 groups the radionuclides according to theirmain industrial, medical and research applications.
Decay modes (graphs)Information about the modes of decay for eachradionuclide is provided in the form of two graphs.The first provides an indication of the energies of thevarious emissions during decay, along with thefraction of decays that give rise to each emission.The second provides an indication of the nucleartransformations that arise during each decay. Forexample, the two graphs for strontium-90 are shownin Figure 12.
Figure 12: Decay mode graphs for strontium-90
The left-hand graph shows the decay energies anddecay fractions. The right-hand graph is a simplifieddecay scheme, which indicates the nucleartransformation that takes place during the betadecay of strontium-90. Decay data were obtainedfrom ICRP Publication 38.
Environment Agency Radionuclides Handbook 19
Parent
Daughter
Detection
Production Uses
Modes Land
of Air
release Water
Environment Agency Radionuclides Handbook20
Chemical properties/characteristics
The chemical properties of most elements can mosteasily be described using the concept of oxidationnumber. The oxidation number is the number ofelectrons that must be added to a positive ion orremoved from a negative ion to produce a neutralatom. Thus, for example, for vanadium in anoxidation state of +5, five electrons must be addedto produce neutral vanadium.
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Dose effects/dosimetry
A description of thekey radiologicalhazards posed by theradionuclide whentaken up by biota.
Species-specificconsiderations
Specific issues relatingto particular biota - forexample species thatmight acquireparticularly highradiation doses
Speciation
The chemicalproperties of theelement of which theradionuclide is anisotope.
Analogue species
Other elements orradionuclides thatshow similar chemical,environmental orradiological behaviourto the radionuclide.
Table 2 gives anoverview of theproposed substitutes.
Terrestrial Aquatic Atmospheric
A description of the key features of the behaviourof the radionuclide in the terrestrial, aquatic andatmospheric environments
Most radionuclides listed in the Handbook areparticle reactive and will become bound insediments or soil. Table 3 summarises thebehaviour of radionuclides (i.e. particle reactiveversus conservative).
Environmental sink
A description of theultimate fate of theradionuclide in theenvironment
Intake and uptake routes
A description of themost importantradionuclide uptakeroutes for biota
Symbol Analogue(s)Am-241 2nd = Cm NoneAr-41 Ne, Ar, Kr, XeAu-198 NoneBr-82 ClC-11 C-12 C-13 CC-14 C-12 C-13 CCa-45 Ca, Sr, Sr-90Ca-47 Ca, Sr, Sr-90Ce-144 Am,
2nd = Ce, Pr, Nd,Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yband Lu
Cl-36 Cl ClCm-242 Am NoneCm-243 Am NoneCm-244 Am NoneCo-57 Co for plantsCo-58 Co for plantsCo-60 Co for plants
Cs-137 (a, f)Sr-90 (m)
Cr-51 CrCs-134 K KCs-135 K KCs-137 K KDepleted U-238UraniumEr-169 Am,
2nd = Ce, Pr, Nd,Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yband Lu
F-18 NoneFe-59 FeGa-67 GaH-3 H H Ca-14I-123 II-125 I I-129
Symbol Analogue(s)I-129 II-131 I Cs-137In-111 NoneIn-113m NoneK-40 Cs (2nd) KKr-79 Ne, Ar, Kr, XeKr-81 Ne, Ar, Kr, XeKr-85 Ne, Ar, Kr, XeLa-140 Am,
2nd = Ce, Pr, Nd,Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yband Lu
Mn-54 MnMn-56 MnMo-99 MoNa-22 Na for animalsNa-24 Na for animalsNb-94 Zr NoneNb-95 ZrNi-59 Ni NiNi-63 Ni NiNp-237 Np NoneO-15 OP-32 PO4- Cs-137P-33 PO4- Cs-137Pa-234m NonePb-210 Pb, Ca NonePm-147 Ce, Sm, Eu, PmPo-210 Pb-210 NonePu-238 Pu , 2nd = Np, Am,
Cm NonePu-239 Pu , 2nd = Np, Am,
Cm NonePu-240 Pu , 2nd = Np, Am,
Cm NonePu-241 Pu , 2nd = Np, Am,
Cm NoneRa-226 2nd = Ca, Sr, Ba Ca
Environment Agency Radionuclides Handbook 21
Symbol Analogue(s)Rb-81 K, CsRb-86 K, CsRe-186 NoneRn-222 NoneRu-106 None Cs-137S-35 S
Cs-137 (f, m)Sb-125 NoneSe-75 Se, SSm-153 Ce, Eu, SmSr-89 Ca CaSr-90 Ca CaTc-99 Tc N (NO3-)Tc-99m Tc Cs-137Th-227 ThTh-228 Th NoneTh-230 Th NoneTh-231 Th NoneTh-232 Th NoneTh-234 ThTl-201 KTotal Nonealpha Ra-226 (a),
U-238 (f, m)Total Nonebeta Cs-137 (a),
Sr-90 (f, m)U-234 U None U-238U-235 U None U-238U-238 U NoneV-48 VXe-133 Ne, Ar, Kr, XeY-90 Ce, Sr-90Zr-95 Nb
FASSET (Strand et al., 2001)Agency ‘Stage 2’(Allott and Dunn, 2001):
a = airf = freshwaterm = marine waters
Table 2 Radionuclide analogues, listed by radionuclide symbol
Environment Agency Radionuclides Handbook22
Symbol C or PAm-241 PAr-41 CAu-198 PBr-82 CC-11 CC-14 CCa-45 PCa-47 PCe-144 PCl-36 CCm-242 PCm-243 PCm-244 PCo-57 PCo-58 PCo-60 PCr-51 C+PCs-134 PCs-135 PCs-137 P+CEr-169 PF-18 -Fe-59 PGa-67 -H-3 CI-123 CI-125 CI-129 CI-131 CIn-111 -In-113m -K-40 CKr-79 CKr-81 CKr-85 CLa-140 PMn-54 PMn-56 PMo-99 C+PNa-22 CNa-24 CNb-94 PNb-95 P
Symbol C or PNi-59 PNi-63 PNp-237 PO-15 -P-32 C+PP-33 C+PPa-234m - as Th (P)Pb-210 PPm-147 PPo-210 PPu-238 PPu-239 PPu-240 PPu-241 PRa-226 -Rb-81 C+PRb-86 C+PRe-186 -Rn-222 -Ru-106 PS-35 C+PSb-125 CSe-75 PSm-153 PSr-89 CSr-90 CTc-99 P+CTc-99m P+CTh-227 PTh-228 PTh-230 PTh-231 PTh-232 PTh-234 PTl-201 CU-234 CU-235 CU-238 CV-48 C+PXe-133 -Y-90 PZr-95 P
P = Particle reactive, i.e. binds to particlesC = Conservative, i.e. remains in solutionP+C = form will depend on environment (freshwater versus marine)- = not stipulated, usually because of its short half-life.
Table 3 Behaviour of radionuclides, listed by radionuclide symbol
Environment Agency Radionuclides Handbook 23
Rad
ionu
clid
es S
orte
d by
Orig
in
Ato
mic
Mas
s
Hal
f Life
(yr
)
050
100
150
200
250
Tril
lion
Ten
billi
on
Hun
dred
mill
ion
Mill
ion
1000
0
100
0.01
0.00
01
K40
CI-
36
C-1
4
Ni-5
9
Kr-
81
I-12
9 Cs-
135
TC
-99
Nb-
94
Ni-6
3 Kr-
85H
-3N
a-22
Th-
232
U-2
33
U-2
35
Np-
237
U-2
34T
h-23
0P
u-20
9
Pu-
240
Pu-
241
Pu-
238
Ra-
226
Pb-
210
Cs-
137
Sr-
90 Ru-
106
Pm
-147
P-3
2P
-33
S-3
5
Na-
24
F-1
8
Cr-
51
Ca-
47
Ca-
41M
n-56
Ca-
45 V-4
8
Co-
60S
r-89
Mn-
54
Co-
57
Sc-
75
Co-
58F
e-59
Kr-
79B
r-82C
a-67
Rb-
86
Y-9
0
Rb-
81Tc
-99m
In-1
13m
Mo-
99
Zr-
95N
b-95
I-12
5
n-12
1 La-1
40
I-12
3S
m-1
53
Sb-
125C
s-10
4
Ce-
144
I-13
1K
e-13
3B
r-10
9R
a-18
6
Au-
198
TI-
201
Po-
210
Th-
227
Rn-
222
Th-
223
Cm
-242
Th-
234
Th-
231
1
Am
-241
Cm
-243
Cm
-244
Fig
ure
9: O
rig
ins
of r
adio
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ides
Act
ivat
ion
Bre
edin
gC
osm
ogen
icF
issi
onP
rimor
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Rad
ioge
nic
Environment Agency Radionuclides Handbook24
Radionuclides S
orted by Decay M
ode
Atom
ic Mass
Half Life (yr)
050
100150
200250
Trillion
Tenbillion
Hundredm
illion
Million
10000
100
0.01
0.0001
1
K-40
Th-232
U-238
U-235
I-129Cs-135
Kr-81
CI-36
Ni-59
Tc-99
Nb-94
Np-237
U-234
Th-230
Ra-226
Pu-280
Pu-240
Pu-241
Pu-238
Pb-210
Th-228
C-14
Ni-63
Am
-241C
m-243
Cm
-244
Cm
-242
Th-204
Th-231
Sr-90
Cs-137P
m-147
Cs-131
Kr-35
Mn-54
Co-57
H-3
Na-22
Ca-45
S-35
P-32
P-33
Na-24
F-13
Ca-41
Mn-56
Ca-47
Cr-51
V-48
Co-60
Sr-89
Se-75
Ru-106
Zr-95
Nb-95
I-125C
o-58F
e-59R
b-86G
a-67K
r-79B
r-82Y
-90M
o-99
Sb-125
Ce-144
In-111
Rb-81
Tc-99mIn-113m
La-140
I-123S
m-153
I-134X
e-133E
r-160
Po-210
Re-186
Au-198
TI-201
Th-227
Rn-222
Figure 10: M
ain decay m
odes of rad
ionuclides
Alpha
Beta
EC
(X-ray)
IT (G
amm
a Ray)
Environment Agency Radionuclides Handbook 25
Rad
iona
cide
s S
orte
d by
Usa
ge
K-4
0
CI-
36
Ni-5
9
Kr-
81Tc
-99
Nb-
94
C-1
4
Ni-6
3M
n-54
H-3
Na-
22C
o-57
Kr-
85
Co-
60
Sr-
90 Ru-
106
Sr-
89C
a-45
S-3
5
P-3
2P
-33
Na-
24
F-1
8C
a-41
Mn-
56
Ca-
47
Cr-
51V-4
8
Se-
75
Co-
58F
e-59
Rb-
86G
a-67
Kr-
79B
r-82
Tc-9
9m
Y-9
0M
o-99
Nb-
95Z
r-95
I-12
5
In-1
11Sb-
125
La-1
40I-
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In-1
13mC
s-13
4Cs-
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m-1
47
Ce-
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I-13
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3
Sm
-153
Er-
169
Pb-
210
Po-
210
Ti-2
01A
u-19
8
Re-
186
Th-
227
Rn-
222
Ra-
226
Th-
228
Pu-
241
Cm
-244
Th-
230
U-2
34 Pu-
239
Pu-
240
Np-
237
U-2
35
U-2
38
Th-
232
Cm
-243
Am
-241
Pu-
238
Th-
231
Th-
234
Cm
-242
Rb-
81
I-12
9 Cs-
135
Tril
lion
Hal
f Life
(yr
)
Ten
billi
on
Hun
dred
m
illio
n
Mill
ion
1000
0
100
1
0.01
0.00
010
5010
015
020
025
0
Ato
mic
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s
Fig
ure
11:
Mai
n us
es o
f ra
dio
nucl
ides
Indu
stria
lM
edic
alR
esea
rch
Non
e
Environment Agency Radionuclides Handbook26
Allott, R. and Dunn, M., 2001. Assessment ofradioactive discharge screening levels for biotaprotected under the Habitats Regulations.Environment Agency NCAS Technical Report:NCAS/TR/2001/019. Environment Agency,Lancaster.
Copplestone D., Bielby S., Jones S.R., Patton D.,Daniel P and Gize I., 2001. Impact assessment ofionising radiation on wildlife. Environment AgencyR&D Publication 128. Environment Agency, Bristol.
Hill, G. and Holman, J.S., 2000. Chemistry incontext, 5th edition. Nelson Thornes Cheltenham.
International Atomic Energy Agency (IAEA), 1994.Handbook of parameter values for the prediction ofradionuclide transfer in temperate environments.IAEA Technical Reports Series No. 364. IAEA,Vienna.
International Atomic Energy Agency (IAEA), 2000.Safety glossary - terminology used in nuclear,radiation, radioactive waste and transport safety.IAEA version 1, April 2000. Available fromhttp://www.iaea.org/ns/CoordiNet/index.htm (theCoordinNet page of Nuclear Safety).
International Commission on Radiological Protection(ICRP). Radionuclide transformations: energy andintensity of emissions, ICRP Publication 38. Annalsof the ICRP, 11-13, 1983.
National Radiological Protection Board (NRPB), 1998.Living with radiation, 5th edition. NRPB, Chilton,Oxfordshire.
Strand, P., Beresford, N., Avila, R., Jones, S.R. andLarsson, C.-M. (editors), 2001. FASSET DeliverableD1: Identification of candidate reference organismsfrom a radiation exposure pathways perspective,FASSET Contract FIGE-CT-2000-00102. Availablefrom http://www.fasset.org (go to the Resultspage).
United Nations Scientific Committee on the Effects ofAtomic Radiation (UNSCEAR), 1996. Sources andeffects of ionizing radiation. 1996 Report to theGeneral Assembly, with Annexes. United Nations,New York
United Nations Scientific Committee on the Effects ofAtomic Radiation (UNSCEAR), 2000. Exposures tothe public from man-made sources of radiation.2000 Report to the General Assembly, Annex C.United Nations, New York.
Woodhead D. and Zinger I. (editors), 2003. FASSETDeliverable D4: Radiation effects to plants andanimals, FASSET Contract No FIGE-CT-2000-00102.Available from http://www.fasset.org (go to theResults page).
Some useful websites:
http://nucleardata.nuclear.lu.se/nucleardata/toi/Provides additional specialised information aboutthe nuclear properties of radioactive isotopes
http://iaeand.iaea.or.at/formmird.htmlTables of nuclear and atomic radiation fromnuclear decay and decay scheme drawings
http://www.fasset.orgFASSET (Framework for ASSessment ofEnvironmental ImpacT) - an EC 5th Frameworkproject which aims to develop a framework for theassessment of environmental impact of ionisingradiation. Contract No FIGE-CT-2000-00102.
5. References
5
Environment Agency Radionuclides Handbook 27
Publication Content summary
Coughtrey P.J. et al. Radionuclide distribution andtransport in terrestrial and aquatic ecosystems.Balkema, 1983-1985.
A six-volume work that provides a comprehensivereview of environmental behaviour andcharacteristics of the elements.
ECORAD 2001. Proceedings of the InternationalCongress, held Aix-en-Provence, France. IPSN France,2001.
Proceedings of a conference to examine issues of theradioecology and ecotoxicology of continental andestuarine environments
Emsley, J. Nature’s building blocks: An A-Z guide tothe elements. Oxford University Press, 2001.
An introduction to the basic properties of theelements
IAEA. Protection of the environment from the effectsof ionising radiation, IAEA-TECDOC-1091. Vienna,2000.
An IAEA publication that discusses the various issuesrelating to the radiation protection of non-humanspecies.
International Commission on Radiological Protection(ICRP). 1990 recommendations of the InternationalCommission on Radiological Protection, ICRPPublication 60. Annals of the ICRP, 21(1-3), 1991.
Document currently being reviewed to specificallyaddress the protection of the environment. Revisiondue in 2005.
Martin, A. An introduction to radiation protection,4th edition. Chapman and Hall, 1996.
An introductory text that describes the basicconcepts of radiation and how systems of radiationprotection can be developed.
Nuclear Energy Agency/Organisation for EconomicCo-operation and Development (NEA/OECD).Radiological protection of the environment: the pathforward to a new policy? Workshop Proceedings,held Taormina, Sicily, Italy, 12-14 February 2002.
The proceedings of a conference that looked at theissues associated with developing a system ofradiation protection for the environment.
Pentreath, R,J. A system for radiological protection ofthe environment: some initial thoughts and ideas. J.Radiol. Prot., 19, 117-128, 1999.
A discussion of the issues relating to protection of theenvironment, including the notion that protection ofindividuals may be as important as protection ofpopulations.
Thorne, M.C. et al. A model for evaluatingradiological impacts on organisms other than manfor use in post-closure radiological assessments ofgeological repositories for radioactive wastes. JRadiol. Prot. 22(3), 249-277, 2002.
A paper that proposes a model for use in estimatingradiological doses to non-human species fromradionuclides originating in geological wasterepositories.
Van der Stricht, E. and Kirchmann, R. (editors).Radioecology: radioactivity and ecosystems. FortempsDrukkerij, LiËge, Belgium, 2001.
An introduction to radioecology - intended as alearning textbook, not a summary of the latestresearch findings.
Additional reading
The following references provide additional (and sometimes more specialised) information about theradiological consequences of radioactivity to the environment and biota:
Environment Agency Radionuclides Handbook28
PART 2Information on each radionuclide - listed by symbol
Symbol Radionuclide PageAm-241 Americium-241 30Ar-41 Argon-41 32Au-198 Gold-198 34Br-82 Bromine-82 36C-11 Carbon-11 38C-14 Carbon-14 40Ca-45 Calcium-45 42Ca-47 Calcium-47 44Ce-144 Cerium-144 46Cl-36 Chlorine-36 48Cm-242 Curium-242 50Cm-243 Curium-243 52Cm-244 Curium-244 54Co-57 Cobalt-57 56Co-58 Cobalt-58 58Co-60 Cobalt-60 60Cr-51 Chromium-51 62Cs-134 Caesium-134 64Cs-135 Caesium-135 66Cs-137 Caesium-137 68Depleted uranium 70Er-169 Erbium-169 72F-18 Fluorine-18 74Fe-59 Iron-59 76Ga-67 Gallium-67 78H-3 Tritium 80I-123 Iodine-123 82I-125 Iodine-125 84I-129 Iodine-129 86I-131 Iodine-131 88In-111 Indium-111 90In-113m Indium-113m 92K-40 Potassium-40 94Kr-79 Krypton-79 96Kr-81 Krypton-81 98
Symbol Radionuclide PageKr-85 Krypton-85 100La-140 Lanthanum-140 102Mn-54 Manganese-54 104Mn-56 Manganese-56 106Mo-99 Molybdenum-99 108Na-22 Sodium-22 110Na-24 Sodium-24 112Nb-94 Niobium-94 114Nb-95 Niobium-95 116Ni-59 Nickel-59 118Ni-63 Nickel-63 120Np-237 Neptunium-237 122O-15 Oxygen-15 124P-32 Phosphorus-32 126P-33 Phosphorus-33 128Pa-234m Protactinium-234m 130Pm-147 Promethium-147 132Po-210 Polonium-210 134Pb-210 Lead-210 136Pu-238 Plutonium-238 138Pu-239 Plutonium-239 140Pu-240 Plutonium-240 142Pu-241 Plutonium-241 144Ra-226 Radium-226 146Rb-81 Rubidium-81 148Rb-86 Rubidium-86 150Re-186 Rhenium-186 152Rn-222 Radon-222 154Ru-106 Ruthenium-106 156S-35 Sulphur-35 158Sb-125 Antimony-125 160Se-75 Selenium-75 162Sm-153 Samarium-153 164Sr-89 Strontium-89 166Sr-90 Strontium-90 168
Environment Agency Radionuclides Handbook 29
Symbol Radionuclide PageTc-99 Technetium-99 170Tc-99m Technetium-99m 172Th-227 Thorium-227 174Th-228 Thorium-228 176Th-230 Thorium-230 178Th-231 Thorium-231 180Th-232 Thorium-232 182Th-234 Thorium-234 184Tl-201 Thallium-201 186
Symbol Radionuclide PageTotal alpha 188Total beta 189U-234 Uranium-234 190U-235 Uranium-235 192U-238 Uranium-238 194V-48 Vanadium-48 196Xe-133 Xenon-133 198Y-90 Yttrium-90 200Zr-95 Zirconium-95 202
Environment Agency Radionuclides Handbook30
Name
Radioactivehalf-life
Parent
Americium-241
432 years
Pu-241
Symbol
Principal decaymode
Daughter
Am-241
Alpha
Np-237 [R]
Origin
Grouping
Detection
Breeding
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Formed by neutron activation of uranium in a nuclear reactor, followed by decay ofthe activation products
Uses • As an alpha radiation source in smoke detectors
ModesLand
• Deposition to soils as a result of historic weapons testing• Releases from nuclear reactors or reprocessing plants
ofAir
• Releases due to weapons testing• Releases from nuclear reactors or experimental facilities release
Water • Liquid discharges from nuclear facilities
Speciation
The most important oxidation state of americiumin solution is +3, with carbonate expected to bethe dominant form.
The solubility is expected to increase as pHincreases.
Americium compounds hydrolyse in water, oftenaccompanied by colloid formation.
Analogue species
The higher actinides Am and Cm have very similarchemical, biochemical and biogeochemicalcharacteristics.
However, Am has been more extensively studiedthan Cm, so it is more appropriate to regard Amas an analogue for Cm than vice versa.
A
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Environment Agency Radionuclides Handbook 31
Terrestrial
Am-241 deposited in theterrestrial environment willmainly be transferred to soils.
Am-241 is highly particlereactive and therefore bindsstrongly to soils and sediments.
Aquatic
Am-241 is highly particlereactive in the aquaticenvironment and thereforetends to accumulate insediments.
Transport of Am-241 in aquaticsystems (e.g. saltmarsh) willtherefore be determined bysediment transport therein.
Atmospheric
Am-241 is expected to disperseas an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. nitrate, might alsoarise.
Environmental sink
Because of its high particlereactivity, Am-241 will tend toremain in soil systems on atimescale of decades tocenturies. Losses from the soilsystems may occur by erosion.
In aquatic systems, sedimentsare the most likelyenvironmental sink and Am-241migration will be closelyassociated with sedimenttransport.
Intake and uptake routes
Because of its high particle reactivity, Am-241 has a lowbioavailability to plants.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation.
It is also not very available to animals - uptake from thegastrointestinal tract is limited (<0.1 %), but the liver and skeletonwould act as sinks for Am-241.
Dose effects/dosimetry
Am-241 is primarily an alpha emitter.
Activity deposited on the outer layers of organisms(e.g. skin) will therefore be of little radiologicalconsequence.
Species-specific considerations
Therefore, Am-241 is of greatest potentialsignificance when internally incorporated in organsand tissues that are susceptible to the effects ofalpha radiation.
Specific consideration should be given to molluscs,crustaceans and aquatic plants, for whichconcentration factors can be a factor of 1,000 ormore higher than the surrounding water.
A
Environment Agency Radionuclides Handbook32
Name
Radioactivehalf-life
Parent
Argon-41
109 minutes
N/A
Symbol
Principal decaymode
Daughter
Ar-41
Beta [gamma]
K-41
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of stable potassium-41 and argon-40 in gas-cooled nuclear reactors
Uses • No significant uses outside research activities
Modes Land • Not generally released to land
of Air • During venting of coolant gas in gas-cooled nuclear reactors
release Water • Not generally released to water
Speciation
Argon is a noble gas (it has a completely filledouter electron shell).
It forms only a limited number of chemicalcompounds due to its lack of reactivity.
Analogue species
All the noble gases (Ne, Ar, Kr, Xe and Rn) exhibitsimilar environmental behaviour.
Rn is a special case because it is generated in theenvironment from isotopes of radium and becauseit decays to produce chemically reactive, short-lived and long-lived radioactive progeny.
For this reason, Rn should not be used as adosimetric analogue for Ar.
A
Environment Agency Radionuclides Handbook 33
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ar-41 is not readily transferredto the terrestrial environment.
Aquatic
Ar-41 is not transferredsignificantly to the aquaticenvironment.
Atmospheric
Ar-41 is almost exclusivelyreleased to the atmosphere.
Its very short radioactive half-lifeand low reactivity means that itdecays almost entirely duringatmospheric transport and is nottransferred significantly to otherenvironmental media.
Environmental sink
No major sink, owing to its lackof reactivity and very short half-life.
Intake and uptake routes
Ar-41 is sparingly soluble in body tissues, notably those with a highfat content. However, it is not metabolised.
Some Ar-41 will be present in the lungs in inhaled air.
Dose effects/dosimetry
Ar-41 emits energetic gamma rays.
Radiation doses to organisms arise mainly due toexternal irradiation.
Species-specific considerations
Because the main consideration is externalirradiation, there are no major species-dependentconsiderations.
Aquatic organisms, plant roots and burrowinganimals will be shielded, to a greater or lesserdegree, from such exposures.
A
Environment Agency Radionuclides Handbook34
Name
Radioactivehalf-life
Parent
Gold-198
2.7 days
N/A
Symbol
Principal decaymode
Daughter
Au-198
Beta
Hg-198
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced by irradiating stable isotopes with neutrons or protons in a nuclearreactor or cyclotron
Uses • Used in the treatment of brain tumours and ovarian cancer
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Could be released to sewers
Speciation
Gold is an element of the series IB metals. It showsfour oxidation states (+5, +3, +2 and +1); themost common are +3 and +1.
Gold forms a number of organometalliccompounds, as well as compounds with thehalides and oxygen.
Cyanide increases the solubility of gold and itssalts and complexes.
Analogue species
No analogue elements have been identified.
A
Environment Agency Radionuclides Handbook 35
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Au-198 is not expected to bevery mobile in the environment.
Aquatic
Au-198 is likely to be particlereactive.
It is expected to decaysubstantially during its transportthrough the aquatic system.
Atmospheric
Releases of aerosols to theatmosphere could occur duringproduction or use.
Deposition of Au-198 is likely tobe limited on account of itsshort half-life.
Environmental sink
Au-198 in the terrestrialenvironment will remain in situ,either on the external surfacesof plants or on the underlyingsoil.
In aquatic systems, bottomsediments are the most likelyenvironmental sink and Au-198migration will be closelyassociated with sedimenttransport.
Intake and uptake routes
Ingestion of Au-198 might occur by soil fauna and herbivores.
In mammals, gold is moderately well absorbed from thegastrointestinal tract. It then becomes rapidly and relatively uniformlydistributed throughout all organs and tissues.
Plants that metabolise cyanide absorb most gold, as the cyanidehelps to solubilise the gold. Such plants include horsetails, Douglasfir, honeysuckle and Indian mustard (Brassica juncea).
Dose effects/dosimetry
Au-198 is a mixed beta-gamma emitter.
External exposure would be significant. It wouldgive rise to whole-body exposures from thegamma component and superficial exposures fromthe beta component.
Uptake in animals would give a significant beta-gamma component from internal exposure.
Species-specific considerations
In mammals, the rapidity of urinary excretioncould result in doses to the wall of the urinarybladder being substantially larger than those toother organs and tissues.
For plants, consideration needs to be given tovegetation types (e.g. stands of trees) that couldintercept a substantial fraction of the dispersingplume.
A
Environment Agency Radionuclides Handbook36
Name
Radioactivehalf-life
Parent
Bromine-82
35.3 hours
N/A
Symbol
Principal decaymode
Daughter
Br-82
Beta [gamma]
Kr-82
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced by irradiating stable isotopes with neutrons or protons in a nuclearreactor or cyclotron
Uses • Used as a tracer for exchangeable chloride and for measurements of extracellularfluid properties
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Could be released to sewers
Speciation
Bromine is a halogen element that shows apredominant oxidation state of -1.
It is very reactive and forms bromide compoundswith many other elements.
It also forms a series of bromate compoundsinvolving bromine and oxygen.
Analogue species
Chlorine is the most appropriate analogue.
However, as chlorine is an essential element for allplants and animals and bromine is not, thisanalogy should be used with caution.
B
Environment Agency Radionuclides Handbook 37
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Bromide is not particle reactiveand so may be expected tomove freely through theterrestrial environment.
The very short half-life will limitthe extent to which it canmigrate in the terrestrialenvironment.
Aquatic
Bromide will behaveconservatively in aquaticsystems.
The very short half-life will limitthe extent to which it canmigrate in the terrestrialenvironment.
Atmospheric
Br-82 could be released to theatmosphere.
It is dispersed either as areactive vapour or an aerosol,but the very short half-life mayprevent wet and dry deposition.
Br-82 in bromide also reactswith atmospheric oxygen.
Environmental sink
Br-82 will either decay in situ (ifit is retained in plants or takenup by animals) or it will decayas it disperses in surface watersand groundwaters.
Intake and uptake routes
Plants can take up Br-82 by direct foliar absorption, after which it isdispersed relatively uniformly throughout their tissues. Plants mayalso take up bromide through their roots, via soil water.
Animals will take up Br-82 from plants and water bodies. Bromine isessentially completely absorbed from the gastrointestinal tract ofmammals and is relatively uniformly distributed throughout allorgans and tissues of the body.
Br-82 is highly bioavailable to aquatic organisms, namely aquaticplants.
The very short half-life of Br-82 will limit the accumulation process.
Dose effects/dosimetry
Br-82 is a beta emitter and, in addition, a strongemitter of energetic gamma rays.
Organisms will be subjected to external irradiationfrom gamma rays, and gamma rays from internallyincorporated Br-82.
The beta particle will also make a smallcontribution to dose.
Species-specific considerations
Br-82 is thought to be highly bioavailable to awide range of plant and animal species.
B
Environment Agency Radionuclides Handbook38
Name
Radioactivehalf-life
Parent
Carbon-11
20 minutes
N/A
Symbol
Principal decaymode
Daughter
C-11
Beta [gamma]
B-11
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced by irradiating stable isotopes with neutrons or protons in a nuclearreactor or cyclotron
Uses • Labelling of organic compounds in biomedical studies
ModesLand • Sewage sludge application to land, but would probably decay away long
before this can occurof
Air • Not generally released to air release
Water • Could be released to sewers
Speciation
The majority of compounds of carbon are in the+4 oxidation state.
Its chemistry is characterised by its tendency toform stable bonds with oxygen, hydrogen, halides,nitrogen, sulphur and other carbon atoms.
In solution, the carbonate and bicarbonate ionspredominate.
Analogue species
Because of its fundamental role in biochemistryand biogeochemistry, there are no other elementsthat can be considered as environmentalanalogues of carbon.
However, studies of stable carbon behaviour in theenvironment and of distinctions in behaviour of itstwo stable isotopes (C-12 and C-13) provideimportant insights into the environmentalbehaviour of radioactive isotopes of carbon.
C
Environment Agency Radionuclides Handbook 39
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
The very short radioactive half-life of C-11 precludes significanttransport in terrestrialenvironments.
Aquatic
The very short radioactive half-life of C-11 precludes significanttransport in aquaticenvironments.
Atmospheric
The very short radioactive half-life of C-11 precludes significanttransport in atmosphericenvironments.
Environmental sink
Almost all C-11 will be lost byradioactive decay during itsdispersion from the source.
Almost all that is taken up byplants will decay at the site ofphotosynthesis.
C-11 that is taken up byanimals will rapidly becomerelatively uniformly distributedthroughout the body and decayin situ.
Intake and uptake routes
There is a limited potential for uptake into plants for photosynthesisand into animals by respiration following an atmospheric release.
There is little possibility of significant intake and uptake following anaquatic release.
Dose effects/dosimetry
C-11 emits positrons. These, in turn, generateannihilation radiation in the form of 0.511 MeVphotons.
Uptake into plants could give rise to irradiation byboth beta and gamma radiation. This irradiationwould be expected to be mainly of above groundparts.
Internal irradiation of animals would also be frombeta and gamma irradiation from C-11 distributedreasonably uniformly throughout all organs andtissues of the body.
Species-specific considerations
No specific issues on account of the very shorthalf-life of C-11.
C
Environment Agency Radionuclides Handbook40
Name
Radioactivehalf-life
Parent
Carbon-14
5,730 years
N/A
Symbol
Principal decaymode
Daughter
C-14
Beta
N-14
Origin
Grouping
Detection
Cosmogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Naturally in the upper atmosphere due to cosmic ray interactions• In nuclear reactors by neutron irradiation of carbon and nitrogen
Uses • Radiocarbon dating• Diagnostic medical procedures (e.g. studies of gigantism)
ModesLand • Deposition of fallout from a nuclear accident or natural processes
of Air• Naturally present through cosmic ray interactions• Historic weapons testing
releaseWater
• Transfer from atmosphere to shallow and deep ocean waters• Liquid discharges from nuclear facilities
Speciation
The majority of compounds of carbon are in the+4 oxidation state.
Its chemistry is characterised by its tendency toform stable bonds with oxygen, hydrogen, halides,nitrogen, sulphur and other carbon atoms.
In solution, the carbonate and bicarbonate ionspredominate.
Analogue species
Because of its fundamental role in biochemistryand biogeochemistry, there are no other elementsthat can be considered as environmentalanalogues of carbon.
However, studies of stable carbon behaviour in theenvironment and of distinctions in behaviour of itstwo stable isotopes (C-12 and C-13) provideimportant insights into the environmentalbehaviour of radioactive isotopes of carbon.
C
Environment Agency Radionuclides Handbook 41
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
C-14 is rapidly dispersedthrough terrestrial environmentsby a wide variety of biological,biochemical andbiogeochemical processes.
For disperse sources, this resultsin similar specific activities fordifferent components of theenvironment.
Aquatic
C-14 is rapidly dispersedthrough aquatic environments.
Atmospheric
C-14 is mainly released to, orproduced in, the atmosphere.
It then becomes globallydispersed on a timescale ofmonths to a few years, i.e. verymuch shorter than itsradioactive half-life.
Environmental sink
Long-term sinks are deep oceanwaters and the deposition ofcarbonaceous sediments.
On shorter time scales, biotacan constitute a sink or source,depending on whether theamount of standing biomass isincreasing or decreasing.
Intake and uptake routes
Plants take up C-14 mainly for photosynthesis (and lose it byrespiration as carbon dioxide).
However, a limited degree of root uptake also occurs and a fewpercent of plant carbon can derive from the soil rather than theabove ground atmosphere.
Animals are mainly exposed to C-14 by ingestion. In the short-term,uptake will be highest in metabolically active tissues, but this tendsto be compensated for in the longer term by higher rates of turnoverin such tissues.
Dose effects/dosimetry
C-14 is a soft beta emitter that becomes relativelyuniformly distributed throughout all organs andtissues in both plants and animals.
Because it is a pure soft beta emitter, dose ratesare entirely determined by concentrations near thepoint of exposure.
Species-specific considerations
If localised releases occur to freshwaters with smalldilution volumes or flow rates, specificconsideration should be given to the very highdegree of uptake that can occur in fish (IAEA,1994).
C
Environment Agency Radionuclides Handbook42
Name
Radioactivehalf-life
Parent
Calcium-45
163 days
N/A
Symbol
Principal decaymode
Daughter
Ca-45
Beta
Sc-45
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron irradiation of stable precursors in a cyclotron or nuclear reactor
Uses • Used in medicine as a tracer to investigate calcium metabolism
Modes Land • Sewage sludge application to land.
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Calcium is an alkaline earth element and, asconsequence, the most important species is theCa2+ ion.
Isotopes of calcium can therefore be expected totake part in a number of precipitation andsubstitution reactions.
Precipitation as sulphate or carbonate is possible.
Analogue species
Sr is a close chemical analogue.
Although Ca is an essential element for almost allbiota, the extensive studies of Sr-90 in theenvironment can sometimes provide usefulinformation about the chemistry, biochemistry andbiogeochemistry of Ca.
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Environment Agency Radionuclides Handbook 43
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ca-45 deposited to soils isexpected to be relatively mobileand thus available for uptake byplants.
Aquatic
Ca-45 can exhibit a relativelyhigh degree of sorption toaquatic sediments and aquatictransport will thus be governedby movement of sediments.
Atmospheric
If released to the atmosphere,Ca-45 would be present as anaerosol.
Atmospheric transport wouldresult in wet and dry depositionto plants and soils.
Environmental sink
The relatively short half-life ofCa-45 means that it is likely todecay close to its site ofdeposition in terrestrialenvironments.
Substantial dispersion is likely inaquatic environments, withdecay either in the watercolumn or in depositedsediments.
Intake and uptake routes
Ca-45 is moderately bioavailable to plants. Foliar uptake can besignificant.
Calcium is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~30 %. It will be translocated mainly tomineral bone, skeleton and carapace.
Concentrations in soft tissues are likely to be at least two orders ofmagnitude lower than concentrations in bone.
The bioavailability of Ca to animals is high (fractional gastrointestinalabsorption ~30 %).
Concentrations of Ca will be low for marine fish, but can be quitehigh for freshwater fish and marine invertebrates.
Dose effects/dosimetry
Ca-45 is a soft beta emitter. Therefore, onlyinternal irradiation is relevant.
Relatively high doses will occur to cells embeddedin, or present on the surfaces of, mineralisedtissues.
Species-specific considerations
Discharges to freshwaters should be given specificconsideration because of the high concentrationratios appropriate to freshwater fish.
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Environment Agency Radionuclides Handbook44
Name
Radioactivehalf-life
Parent
Calcium-47
163 days
N/A
Symbol
Principal decaymode
Daughter
Ca-47
Beta
Sc-47 [R]
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Activation of stable calcium-46 by neutrons in nuclear reactors
Uses • No significant uses outside research activities
Modes Land • Not generally released to land
of Air • Not generally released to air
release Water • Not generally released to water
Speciation
Calcium is an alkaline earth element and, asconsequence, the most important species is theCa2+ ion.
Isotopes of calcium can therefore be expected totake part in a number of precipitation andsubstitution reactions.
Precipitation as sulphate or carbonate is possible.
Analogue species
Sr is a close chemical analogue.
Although Ca is an essential element for almost allbiota, the extensive studies of Sr-90 in theenvironment can sometimes provide usefulinformation about the chemistry, biochemistry andbiogeochemistry of Ca.
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Environment Agency Radionuclides Handbook 45
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ca-47 added to soils is expectedto be relatively mobile and thusavailable for uptake by plants.
Aquatic
Ca-47 can exhibit a relativelyhigh degree of sorption toaquatic sediments and aquatictransport will thus be governedby movement of sediments.
Atmospheric
If released to the atmosphere,Ca-47 would be present as anaerosol.
Atmospheric transport wouldresult in wet and dry depositionto plants and soils.
Environmental sink
The short half-life of Ca-47means that it is likely to decayclose to its site of deposition interrestrial environments.
Substantial dispersion is likely inaquatic environments, withdecay either in the watercolumn or in depositedsediments.
Intake and uptake routes
Ca-47 is moderately bioavailable to plants. Foliar uptake can besignificant.
Calcium is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~30 %. It will be translocated mainly tomineral bone, skeleton and carapace. Because of its short half-life,only limited accumulation in bone is expected.
The bioavailability of Ca to animals is high (fractional gastrointestinalabsorption ~30 %).
Concentrations of Ca will be low for marine fish, but can be quitehigh for freshwater fish and marine invertebrates.
Dose effects/dosimetry
Ca-47 is a mixed beta-gamma emitter.
External irradiation from the plume or initialterrestrial deposits may be more important thaninternal uptake by terrestrial biota because of theshort half-life of the radionuclide.
Species-specific considerations
No special considerations on account of the shorthalf-life of Ca-47.
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Environment Agency Radionuclides Handbook46
Name
Radioactivehalf-life
Parent
Cerium-144
285 days
N/A
Symbol
Principal decaymode
Daughter
Ce-144
Beta
Pr-144 [R]
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses • No significant uses outside research activities
Modes Land • During treatment and disposal of spent fuel
of Air • During treatment and disposal of spent fuel
release Water • During treatment and disposal of spent fuel• Liquid discharges from nuclear facilities
Speciation
Cerium is a rare-earth element that showsoxidation states of +3 and +4.
As such, cerium forms compounds with hydrogen,oxygen and the halides. It also forms stablecomplexes.
Analogue species
The rare earth elements (Ce, Pr, Nd, Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) exhibit similarchemical, biochemical and biogeochemicalcharacteristics. However, these characteristicschange systematically in the group with increasingatomic number. Cerium is one of the best-studiedmembers of the group.
Analogies with other members of the group andwith higher actinides such as Am can be useful.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ce-144 is highly particlereactive and hence wouldremain bound to soil particlesand on the surfaces of plants.
Transfers from plant to soil andbulk movement of soils wouldbe the main transportmechanisms.
Aquatic
Ce-144 is highly particlereactive. It is likely to bind tosuspended sediments.
Atmospheric
If released to the atmosphere,Ce-144 would be present as anaerosol, probably as the oxide.
Atmospheric transport wouldresult in wet and dry depositionto plants and soils.
Environmental sink
The relatively short half-life andhigh particle reactivity of Ce-144 mean that it is likely todecay close to its site ofdeposition in terrestrialenvironments.
In aquatic environments,bottom sediments close to thesource of release may form animportant sink.
Intake and uptake routes
Ce-144 is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically <0.1 %. Any Ce-144 that isabsorbed is mainly deposited in the liver and skeleton.
Intake by terrestrial animals is likely to be mainly by ingestion of Ce-144 present on the exterior surfaces of plants or deposited on soil.Very little uptake from the gastrointestinal tract is anticipated, exceptperhaps in pre-weaned animals.
In the aquatic environment, uptake by fish and invertebrates ismainly direct from the water rather than from food. Uptake byaquatic plants is likely to be by surface adsorption.
Dose effects/dosimetry
Ce-144 is a mixed beta-gamma emitter.
External irradiation from activity deposited in theterrestrial environment could be of greaterimportance than internal exposure.
Species-specific considerations
In mammals and birds, the walls of thegastrointestinal tract are likely to receivesubstantially higher doses than other organs andtissues. This is due to irradiation by unabsorbedCe-144 passing through the tract.
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Environment Agency Radionuclides Handbook48
Name
Radioactivehalf-life
Parent
Chlorine-36
3.01 x 105yrs
N/A
Symbol
Principal decaymode
Daughter
Cl-36
Beta
Ar-36
Origin
Grouping
Detection
Cosmogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Cosmic ray interactions in the upper atmosphere• Neutron irradiation of residual chlorine in reactor graphite rods
Uses • Radiological dating of sediment and glacial deposits
Modes Land • Treatment and disposal of spent fuel and reactor hardware
of Air • Treatment and disposal of spent fuel and reactor hardware
release Water • Treatment and disposal of spent fuel and reactor hardware
Speciation
Chlorine is a halogen element.
It shows an oxidation state of -1 in chloridecompounds, and states of +1 and others inchlorate compounds (these contain chlorine andoxygen).
In environmental situations, the chloride speciesare of greatest importance.
Analogue species
There are chemical similarities between F, Cl, Brand I. However, the biochemical roles andbehaviour of these elements are very different.
The only chemical analogue to Cl-36 is perhapsthe stable Cl element.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Cl-36 is of greatest interestwhen it contaminates soils. Itexhibits the highest plant:soilconcentration ratio of anyradionuclide.
In contaminated soils, themajority of the Cl-36 may havebeen translocated to plantswithin a few weeks.
Aquatic
Cl-36 is highly conservative inwaters and is, therefore, readilytransported through the aquaticenvironment.
It may be rapidly dispersed inwater bodies or enter the soilsystem.
Atmospheric
If released to atmosphere, Cl-36would be expected to be widelydispersed and readilybioavailable to both plants andanimals.
Environmental sink
Cl-36 disperses into the largepool of stable chloride that ispresent in the environment.
As chloride is mobile ingroundwaters and surfacewaters, the Cl-36 will tend tomigrate in the long-term to themarine environment anddisperse throughout the worldísoceans.
Intake and uptake routes
Cl-36 is highly accumulated by plants from soils. Cl-36 present in thisplant material is then highly bioavailable to animals.
These terrestrial foodchain pathways are thought to be of greaterimportance than aquatic pathways due to the rapid dilution anddispersion of Cl-36 in surface waters and the limited degree ofconcentration even by freshwater organisms.
Dose effects/dosimetry
Cl-36 is a pure beta emitter.
It is relatively uniformly distributed throughoutplant and animal body tissues.
For dosimetric purposes, it is often useful to adopta specific activity model in which the ratio of Cl-36to stable chlorine is assumed to be the same insource and receptor components of theenvironment.
Species-specific considerations
No major species-specific considerations arisebecause chlorine is ubiquitously present in plantand animal tissues, and is relatively uniformlydistributed throughout them.
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Environment Agency Radionuclides Handbook50
Name
Radioactivehalf-life
Parent
Curium-242
163 days
Am-242
Symbol
Principal decaymode
Daughter
Cm-242
Alpha
Pu-238 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Successive capture of neutrons by plutonium and americium in a nuclear reactor,followed by decay of the products
Uses • Source of power in satellites and other space equipment• Source of alpha particles for analysis of moon surface
Modes Land • Deposition following atmospheric testing of nuclear weapons• As a result of nuclear accidents and releases from nuclear facilities
of Air • Atmospheric testing of nuclear weapons
release Water • Leaching from soils to groundwater
Speciation
Most curium compounds are based on anoxidation state of +3.
For example, it forms trihalide compounds (e.g.CmF3), although compounds such as CmO2 areexamples of the +4 oxidation state.
Curium and its compounds are capable of theformation and precipitation of colloids and organiccomplexes.
Analogue species
The two higher actinides, Am and Cm, have verysimilar chemical, biochemical and biogeochemicalcharacteristics.
However, Am has been more extensively studiedthan Cm, so it is appropriate to regard Am as ananalogue for Cm.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Cm-242 is highly particlereactive and therefore bindsstrongly to soils and sediments.
It is strongly excluded fromplants and is mainly present ontheir surfaces as externalcontamination.
It is also not very available toanimals
Aquatic
Cm-242 is highly particlereactive in the aquaticenvironment and thereforetends to be accumulated in thebottom sediments.
Atmospheric
Cm-242 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. nitrate, might alsoarise.
Environmental sink
Cm-242 deposited in theterrestrial environment willmainly be transferred to soils.
It will tend to remain in suchsoil systems until it decays.
In aquatic systems, bottomsediments are the most likelyenvironmental sink and Cm-242migration will be closelyassociated with sedimenttransport
Intake and uptake routes
Because of its high particle reactivity, Cm-242 shows lowbioavailability to plants.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation (e.g. re-suspendedsoils and sediments).
Although uptake from the gastrointestinal tract is limited (<0.1 %),enhanced concentrations of Cm-242 may occur in the liver andskeleton.
Marine and freshwater fish concentrations are about a factor of 50higher than concentrations in water. Concentrations in molluscs,crustaceans and marine plants can be a factor of 1,000 higher thanthe surrounding water.
Dose effects/dosimetry
Cm-242 is primarily an alpha emitter.
Activity deposited on the outer layers of organisms(e.g. skin) will therefore be of little radiologicalconsequence.
Cm-242 is of greatest potential significance wheninternally incorporated in organs and tissues thatare susceptible to the effects of alpha radiation.
Species-specific considerations
Specific consideration should be given to molluscs,crustaceans and marine plants for whichconcentration factors can be a factor of 1,000 ormore higher than the surrounding water.
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Environment Agency Radionuclides Handbook52
Name
Radioactivehalf-life
Parent
Curium-243
28.5 years
N/A
Symbol
Principal decaymode
Daughter
Cm-243
Alpha
Pu-239 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Successive capture of neutrons by plutonium and americium in a nuclear reactor,followed by decay of the products
Uses • No specific use other than research activities
Modes Land• Deposition following atmospheric testing of nuclear weapons• As a result of nuclear accidents and releases from nuclear facilities
ofAir • Atmospheric testing of nuclear weapons
releaseWater • Leaching from soils to groundwater
Speciation
Most curium compounds are based on anoxidation state of +3 for curium.
For example, it forms trihalide compounds (e.g.CmF3), although compounds such as CmO2 areexamples of the +4 oxidation state.
Curium and its compounds are capable of theformation and precipitation of colloids and organiccomplexes.
Analogue species
The two higher actinides, Am and Cm, have verysimilar chemical, biochemical and biogeochemicalcharacteristics.
However, Am has been more extensively studiedthan Cm, so it is appropriate to regard Am as ananalogue for Cm.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Cm-243 is highly particlereactive and therefore bindsstrongly to soils and sediments.
It is strongly excluded fromplants and is mainly present ontheir surfaces as externalcontamination.
It is also not very available toanimals
Aquatic
Cm-243 is highly particlereactive in the aquaticenvironment and thereforetends to accumulate in thebottom sediments.
Atmospheric
Cm-243 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. nitrate, might alsoarise.
Environmental sink
Cm-243 deposited in theterrestrial environment willmainly be transferred to soils.
It will tend to remain in suchsoil systems until it decays.
In aquatic systems, bottomsediments are the most likelyenvironmental sink and Cm-243migration will be closelyassociated with sedimenttransport.
Intake and uptake routes
Because of its high particle reactivity, Cm-243 shows lowbioavailability to plants.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation (e.g. re-suspendedsoils and sediments).
Although uptake from the gastrointestinal tract is limited (<0.1 %),enhanced concentrations of Cm-243 may occur in the liver andskeleton.
Marine and freshwater fish concentrations are about a factor of 50higher than concentrations in water. Concentrations in molluscs,crustaceans and marine plants can be a factor of 1,000 higher thanthe surrounding water.
Dose effects/dosimetry
Cm-243 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Cm-243 is of greatest potential significance wheninternally incorporated in organs and tissues thatare susceptible to the effects of alpha radiation.
Species-specific considerations
Specific consideration should be given to molluscs,crustaceans and aquatic plants for whichconcentration factors can be a factor of 1,000 ormore higher than the surrounding water.
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Environment Agency Radionuclides Handbook54
Name
Radioactivehalf-life
Parent
Curium-244
18.1 years
Cf-248
Symbol
Principal decaymode
Daughter
Cm-244
Alpha
Pu-240 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Successive capture of neutrons by plutonium and americium in a nuclear reactor,followed by decay of the products
Uses • No specific use other than research activities
Modes Land• Deposition following atmospheric testing of nuclear weapons• As a result of nuclear accidents and releases from nuclear facilities
ofAir • Atmospheric testing of nuclear weapons
releaseWater • Leaching from soils to groundwater
Speciation
Most curium compounds are based on anoxidation state of +3 for curium.
For example, it forms trihalide compounds (e.g.CmF3), although compounds such as CmO2 areexamples of the +4 oxidation state.
Curium and its compounds are capable of theformation and precipitation of colloids and organiccomplexes.
Analogue species
The two higher actinides, Am and Cm, have verysimilar chemical, biochemical and biogeochemicalcharacteristics.
However, Am has been more extensively studiedthan Cm, so it is appropriate to regard Am as ananalogue for Cm.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Cm-244 is highly particlereactive and therefore bindsstrongly to soils and sediments.
It is strongly excluded fromplants and is mainly present ontheir surfaces as externalcontamination.
It is also not very available toanimals
Aquatic
Cm-244 is highly particlereactive in the aquaticenvironment and thereforetends to accumulate in thebottom sediments.
Atmospheric
Cm-244 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. nitrate, might alsoarise.
Environmental sink
Cm-244 deposited in theterrestrial environment willmainly be transferred to soils.
It will tend to remain in suchsoil systems until it decays.
In aquatic systems, bottomsediments are the most likelyenvironmental sink and Cm-244migration will be closelyassociated with sedimenttransport.
Intake and uptake routes
Because of its high particle reactivity, Cm-244 shows lowbioavailability to plants.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation (e.g. re-suspendedsoils and sediments).
Although uptake from the gastrointestinal tract is limited (<0.1 %),enhanced concentrations of Cm-244 may occur in the liver andskeleton.
Marine and freshwater fish concentrations are about a factor of 50higher than concentrations in water. Concentrations in molluscs,crustaceans and marine plants can be a factor of 1,000 higher thanthe surrounding water.
Dose effects/dosimetry
Cm-244 is primarily an alpha emitter.
Activity deposited on the outer layers (e.g. skin) oforganisms will therefore be of little radiologicalconsequence.
Cm-244 is of greatest potential significance wheninternally incorporated in organs and tissues thatare susceptible to the effects of alpha radiation.
Species-specific considerations
Specific consideration should be given to molluscs,crustaceans and aquatic plants for whichconcentration factors can be a factor of 1,000 ormore higher than the surrounding water.
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Environment Agency Radionuclides Handbook56
Name
Radioactivehalf-life
Parent
Cobalt-57
271 days
Cf-248
Symbol
Principal decaymode
Daughter
Co-57
EC
Fe-57
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of other transition metals present in the structural steelsof reactor vessels
Uses • In medicine for diagnostic purposes
Modes Land • Treatment and disposal of spent fuel and reactor hardware
of Air • Treatment and disposal of spent fuel and reactor hardware
release Water • Treatment and disposal of spent fuel and reactor hardware
Speciation
Cobalt is a transition metal element that showstwo common oxidation states (+2 and +3).
In the +2 state, it forms a wide range of ioniccompounds including the oxide, hydroxide andhalides.
In the +3 oxidation state, it forms a wide range ofcomplexes.
Analogue species
Cobalt is an essential element for animals becauseof its central role in vitamin B12.
Therefore, whereas analogies with other transitionmetals may be made for plants, this is not thoughtto be appropriate for animals.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Co-57 is highly particle reactiveand tends to be absorbed to thesurface of clay minerals throughiron and manganese oxides.
It can be mobile in organic oracid soils, but tends to beimmobile in alkaline or neutralsoils.
Aquatic
Co-57 is highly reactive withaquatic sediments and tends tobe migrate from the watercolumn to bottom sediments.
Atmospheric
Co-57 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. chloride, might alsoarise
Environmental sink
As Co-57 has a half-life of only271 days and is highly particlereactive, it can be expected tobe retained in terrestrial soilsand sediments, and to decay insitu.
In the aquatic environment, Co-57 will either decay in thewater column or in bottomsediments close to its point ofdeposition.
Intake and uptake routes
Root uptake by plants is not a significant uptake mechanism for Co-57.
Cobalt is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~20 %.
Animal intakes will be mainly by ingestion of contaminated plants,with a secondary contribution from soil consumption.
Concentrations in aquatic plants, molluscs and crustaceans are about1,000 higher than the surrounding water.
Concentration ratios in freshwater fish relative to water vary fromabout 10 to 1,000 or more. However, values for marine fish aretypically about 1.
Dose effects/dosimetry
Co-57 emits gamma rays following decay byelectron capture.
As Co-57 is relatively uniformly distributed in plantand animal tissues, gamma doses to all organs andtissues will be similar.
Species-specific considerations
The high concentration ratios exhibited by manyaquatic organisms may mean that these are ofparticular interest.
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Environment Agency Radionuclides Handbook58
Name
Radioactivehalf-life
Parent
Cobalt-58
71 days
N/A
Symbol
Principal decaymode
Daughter
Co-58
Beta [gamma]
Fe-58
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of other transition metals present in the structural steelsof reactor vessels
Uses • In medicine for diagnostic purposes
Modes Land • Treatment and disposal of spent fuel and reactor hardware
of Air • Treatment and disposal of spent fuel and reactor hardware
release Water • Treatment and disposal of spent fuel and reactor hardware
Speciation
Cobalt is a transition metal element that showstwo common oxidation states (+2 and +3).
In the +2 state, it forms a wide range of ioniccompounds including the oxide, hydroxide andhalides.
In the +3 oxidation state, it forms a wide range ofcomplexes.
Analogue species
Cobalt is an essential element for animals becauseof its central role in vitamin B12.
Therefore, whereas analogies with other transitionmetals may be made for plants, this is not thoughtto be appropriate for animals.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Co-58 is highly particle reactiveand tends to be absorbed to thesurface of clay minerals throughiron and manganese oxides.
It can be mobile in organic oracid soils, but tends to beimmobile in alkaline or neutralsoils.
Aquatic
Co-58 is highly reactive withaquatic sediments and tends tobe migrate from the watercolumn to bottom sediments.
Atmospheric
Co-58 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. chloride, might alsoarise
Environmental sink
As Co-58 has a half-life of only71 days and is highly particlereactive, it can be expected tobe retained in terrestrial soilsand sediments, and to decay insitu.
In the aquatic environment, Co-58 will either decay in thewater column or in bottomsediments close to its point ofdeposition.
Intake and uptake routes
Root uptake by plants is not a significant uptake mechanism for Co-58.
Cobalt is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~20 %.
Animal intakes will be mainly by ingestion of contaminated plants,with a secondary contribution from soil consumption.
Concentrations in aquatic plants, molluscs and crustaceans are about1,000 higher than the surrounding water.
Concentration ratios in freshwater fish relative to water vary fromabout 10 to 1,000 or more. However, values for marine fish aretypically about 1.
Dose effects/dosimetry
Co-58 is a beta-gamma emitter.
As Co-58 is relatively uniformly distributed in plantand animal tissues, gamma doses to all organs andtissues will be similar.
Species-specific considerations
The high concentration ratios exhibited by manyaquatic organisms may mean that these are ofparticular interest.
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Environment Agency Radionuclides Handbook60
Name
Radioactivehalf-life
Parent
Cobalt-60
5.27 years
Co-60m
Symbol
Principal decaymode
Daughter
Co-60
Beta [gamma]
Ni-60
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of stable cobalt-59 present in the structural steelsof reactor vessels
Uses• Detection of flaws in welded joints and castings• In medicine as an irradiation source in the treatment of cancer
ModesLand • Treatment and disposal of spent fuel and reactor hardware
ofAir • Treatment and disposal of spent fuel and reactor hardware
release Water• Treatment and disposal of spent fuel and reactor hardware• Liquid discharges from nuclear facilities
Speciation
Cobalt is a transition metal element that showstwo common oxidation states (+2 and +3).
In the +2 state, it forms a wide range of ioniccompounds including the oxide, hydroxide andhalides.
In the +3 oxidation state, it forms a wide range ofcomplexes.
Analogue species
Cobalt is an essential element for animals becauseof its central role in vitamin B12.
Therefore, whereas analogies with other transitionmetals may be made for plants, this is not thoughtto be appropriate for animals.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Co-60 is highly particle reactiveand tends to be absorbed to thesurface of clay minerals throughiron and manganese oxides.
It can be mobile in organic oracid soils, but tends to beimmobile in alkaline or neutralsoils.
Aquatic
Co-60 is highly reactive withaquatic sediments and tends tobe migrate from the watercolumn to bottom sediments.
Atmospheric
Co-60 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. chloride, might alsoarise
Environmental sink
As Co-60 is highly particlereactive, it can be expected tobe retained in terrestrial soilsand sediments, and to decay insitu.
In the aquatic environment, Co-60 will either decay in thewater column or in bottomsediments close to its point ofdeposition.
Intake and uptake routes
Root uptake by plants is not a significant uptake mechanism for Co-60.
Cobalt is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~20 %.
Animal intakes will be mainly by ingestion of contaminated plants,with a secondary contribution from soil consumption.
Concentrations in aquatic plants, molluscs and crustaceans are about1,000 higher than the surrounding water.
Concentration ratios in freshwater fish relative to water vary fromabout 10 to 1,000 or more. However, values for marine fish aretypically about 1.
Dose effects/dosimetry
Co-60 is a beta-gamma emitter.
As Co-60 is relatively uniformly distributed in plantand animal tissues, gamma doses to all organs andtissues will be similar.
Species-specific considerations
The high concentration ratios exhibited by manyaquatic organisms may mean that these are ofparticular interest.
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Environment Agency Radionuclides Handbook62
Name
Radioactivehalf-life
Parent
Chromium-51
27.7 days
N/A
Symbol
Principal decaymode
Daughter
Cr-51
EC
V-51
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses• In medicine as a tracer to label red blood cells• To assist in the treatment of bone cancer
Modes Land • Sewage sludge application to land.
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Chromium is a transition metal that can show alloxidation states from -2 through to +6.
The chemistry of chromium and its compounds istherefore very wide and varied.
Chromium has a number of oxides, formscompounds with the halogens, and can formorganic complexes.
Analogue species
Cr has been extensively studied in its own right,both as an essential trace element and as achemical carcinogen. Therefore, there is no needto rely on analogues to characterise its behaviour.
Cr has some chemical, biochemical andbiogeochemical affinities with the other transitionmetals. However, these affinities are not very close.
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Environment Agency Radionuclides Handbook 63
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Uptake of Cr by plants fromsoils is limited. Taking intoaccount the short half-life of Cr-51, external deposition onplants is of greatest interest.
The availability of Cr to animalsis low for trivalent forms butmoderate for hexavalent forms.
Aquatic
The degree of interaction of Crwith sediments depends onchemical form.
Trivalent Cr is highly sorbed,whereas hexavalent Cr is lessstrongly sorbed and asubstantial fraction can remainin solution.
Atmospheric
If Cr-51 was released toatmosphere, it would probablybe as an aerosol.
Environmental sink
The short half-life of Cr-51means that it will often decayclose to its point of depositionin terrestrial environments.
In aquatic environments,trivalent Cr-51 is likely to decayin bottom sediments.
However, hexavalent Cr-51 maybe widely dispersed and mainlydecay in the water column.
Intake and uptake routes
Uptake of Cr by plants from soils is limited. Taking into account theshort half-life of Cr-51, external deposition on plants is of greatestinterest.
The availability of Cr to animals is low for trivalent forms butmoderate for hexavalent forms and Cr incorporated into foodstuffs.
Cr-51 exhibits variable, but often high concentration ratios relative towater in aquatic organisms (typically from a few hundred to a fewthousand).
Cr-51 is likely to be widely distributed throughout the tissues of bothterrestrial and aquatic organisms.
Dose effects/dosimetry
Cr-51 emits a gamma ray of moderate energy inabout 10 % of its transformations.
As Cr-51 is uniformly distributed through allorgans and tissues, the overall dose will beuniformly distributed through the body.
Species-specific considerations
The conservative behaviour of hexavalent Cr-51 inaquatic systems and the high concentration ratiosrelative to water for Cr-51 of many aquaticorganisms make these species of particular interest.
CC
Environment Agency Radionuclides Handbook64
Name
Radioactivehalf-life
Parent
Caesium-134
2.06 years
N/A
Symbol
Principal decaymode
Daughter
Cs-134
Beta [gamma]
Ba-134
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • As a result of fission processes in a nuclear reactor
Uses • Uses for scientific research
Modes Land • Deposition following weapons tests or a nuclear accident
of Air • Discharge to air following weapons tests or a nuclear accident
release Water • Discharge to the sea from operating nuclear facilities
Speciation
Caesium is an alkali metal whose chemicalbehaviour is determined by the properties of theCs+ ion.
Most of the compounds of caesium are ionic innature, although more complex species can beformed.
Caesium reacts extremely vigorously with water,oxygen and halogens.
Analogue species
Cr has been extensively studied in its own right,both as an essential trace element and as achemical carcinogen. Therefore, there is no needto rely on analogues to characterise its behaviour.
Cr has some chemical, biochemical andbiogeochemical affinities with the other transitionmetals. However, these affinities are not very close.
C
Environment Agency Radionuclides Handbook 65
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Cs-134 binds strongly to theclay fraction in soils andsediments.
However, it can also berelatively highly available forplant uptake, particularly inorganic and K-deficient soils.
Cs-134 is transferred from plantsurfaces to soils in around 5-30days.
Aquatic
Cs-134 is moderately particlereactive in marineenvironments, so dispersion inwaters and loss to bottomsediments are both possible.
In freshwaters, Cs-134 can bemore highly particle reactiveand subject to local deposition.
Atmospheric
Cs is a highly volatile element.Thus, Cs-134 is likely to be ofimportance in atmosphericreleases from nuclear accidents.
It would be released anddispersed as an aerosol.
Environmental sink
The high particle reactivity ofCs-134 means that it is likely todecay close to its site ofdeposition in terrestrialenvironments.
In aquatic environments, Cs-134 can be widely dispersedand may decay either in thewater column or in depositedsediments.
Intake and uptake routes
Cs-134 can be relatively highly available for plant uptake, particularlyin organic and K-deficient soils.
Cs-134 is highly bioavailable to animals and is almost completelyabsorbed from the gastrointestinal tract.
It distributes reasonably uniformly through most organs and tissuesof the body, but concentrates to some degree in muscle.
Concentration ratios relative to water are about 100 for marine fish,30-50 for marine invertebrates and plants, but about 1,000 forfreshwater fish.
Muscle is the primary site of deposition in freshwater fish.
Dose effects/dosimetry
The main emissions from Cs-134 are moderatelyenergetic gamma rays.
Therefore, external irradiation, e.g. from soils andsediments, can be important.
The relatively uniform distribution of Cs-134 inbiota and the penetrating power of the emittedgamma rays mean that individual organ and tissuedoses are generally of comparable magnitude tothe average whole-body dose.
Species-specific considerations
The high concentration ratios for freshwater fishmake the exposure of freshwater fish appropriatefor specific consideration.
Plant uptake in K-deficient areas or areas withorganic soils subject to wet deposition is also ofpotential importance.
Uptake in animals grazing such areas also needs tobe considered.
C
Environment Agency Radionuclides Handbook66
Name
Radioactivehalf-life
Parent
Caesium-135
2.3 x 106 years
N/A
Symbol
Principal decaymode
Daughter
Cs-135
Beta
Ba-135
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • As a result of fission processes in a nuclear reactor
Uses • No specific uses, except for scientific research
Modes Land • Deposition following weapons tests or a nuclear accident
of Air • Discharge to air following weapons tests or a nuclear accident
release Water • Discharge to the sea from operating nuclear facilities
Speciation
Caesium is an alkali metal whose chemicalbehaviour is determined by the properties of theCs+ ion.
Most of the compounds of caesium are ionic innature, although more complex species can beformed.
Caesium reacts extremely vigorously with water,oxygen and halogens.
Analogue species
Cs exhibits many chemical, biochemical andbiogeochemical similarities to K.
Cs:K ratios have often been used to characterisethe environmental behaviour of Cs.
C
Environment Agency Radionuclides Handbook 67
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Cs-135 binds strongly to theclay fraction in soils andsediments.
However, it can also berelatively highly available forplant uptake, particularly inorganic and K-deficient soils.
Cs-135 is translocated fromplant surfaces to soils in around5-30 days
Aquatic
Cs-135 is moderately particlereactive in marineenvironments, so dispersion inwaters competes effectively withloss to bottom sediments.
In freshwaters, Cs-135 can bemore highly particle reactiveand subject to local deposition.
Atmospheric
Cs is a highly volatile element.Thus, Cs-135 is likely to be ofimportance in atmosphericreleases from nuclear accidents.
It would be released anddispersed as an aerosol.
Environmental sink
The high particle reactivity ofCs-135 means that it is likely todecay close to its site ofdeposition in terrestrialenvironments.
In aquatic environments, Cs-135 can be widely dispersedand may decay either in thewater column or in depositedsediments.
Intake and uptake routes
Cs-135 can be relatively highly available for plant uptake, particularlyin organic and K-deficient soils.
Cs-135 is highly bioavailable to animals and is almost completelyabsorbed from the gastrointestinal tract.
It distributes reasonably uniformly throughout all organs and tissuesof the body, but concentrates to some degree in muscle.
Concentration ratios relative to water are about 100 for marine fish,30-50 for marine invertebrates and plants, but about 1,000 forfreshwater fish.
Muscle is the primary site of deposition in freshwater fish.
Dose effects/dosimetry
Cs-135 is a soft beta emitter.
Therefore, external exposure is of no importance.
Because Cs-135 is relatively uniformly distributedin tissues, doses to individual organs and tissuesare of comparable magnitude to average whole-body doses.
Species-specific considerations
The high concentration ratios for freshwater fishmake the exposure of freshwater fish appropriatefor specific consideration.
Plant uptake in K-deficient areas or areas withorganic soils subject to wet deposition is also ofpotential importance.
Uptake in animals grazing such areas also needs tobe considered.
CC
Environment Agency Radionuclides Handbook68
Name
Radioactivehalf-life
Parent
Caesium-137
30 years
N/A
Symbol
Principal decaymode
Daughter
Cs-137
Beta [gamma]
Ba-137m [R]
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • As a result of fission processes in a nuclear reactor
Uses• As a radiation source in the treatment of cancer (brachytherapy)• For detecting cracks and imperfections in metal structures
Modes Land• Deposition following weapons tests or a nuclear accident• Disposal of medical sources
ofAir • Discharge to air following weapons tests or a nuclear accident
releaseWater • Discharge to the sea from operating nuclear facilities
Speciation
Caesium is an alkali metal whose chemicalbehaviour is determined by the properties of theCs+ ion.
Most of the compounds of caesium are ionic innature, although more complex species can beformed.
Caesium reacts extremely vigorously with water,oxygen and halogens.
Analogue species
Cs exhibits many chemical, biochemical andbiogeochemical similarities to K.
Cs:K ratios have often been used to characterisethe environmental behaviour of Cs.
C
Environment Agency Radionuclides Handbook 69
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Cs-137 binds strongly to theclay fraction in soils andsediments.
However, it can also berelatively highly available forplant uptake, particularly inorganic and K-deficient soils.
Cs-137 is translocated fromplant surfaces to soils in around5-30 days
Aquatic
Cs-137 is moderately particlereactive in marineenvironments, so dispersion inwaters competes effectively withloss to bottom sediments.
In freshwaters, Cs-137 can bemore highly particle reactiveand subject to local deposition.
Atmospheric
Cs is a highly volatile element.Thus, Cs-137 is likely to be ofimportance in atmosphericreleases from nuclear accidents.
It would be released anddispersed as an aerosol.
Environmental sink
The high particle reactivity ofCs-137 means that it is likely todecay close to its site ofdeposition in terrestrialenvironments.
In aquatic environments, Cs-137 can be widely dispersedand may decay either in thewater column or in depositedsediments.
Intake and uptake routes
Cs-137 can be relatively highly available for plant uptake, particularlyin organic and K-deficient soils.
Cs-137 is highly bioavailable to animals and is almost completelyabsorbed from the gastrointestinal tract.
It distributes reasonably uniformly throughout all organs and tissuesof the body, but concentrates to some degree in muscle.
Concentration ratios relative to water are about 100 for marine fish,30-50 for marine invertebrates and plants, but about 1,000 forfreshwater fish.
Muscle is the primary site of deposition in freshwater fish.
Dose effects/dosimetry
The main emissions from Cs-137 and its veryshort-lived daughter Ba-137m are beta particlesand moderately energetic gamma rays.
Therefore, external irradiation (e.g. from soils andsediments) can be important.
The relatively uniform distribution of Cs-137 inbiota means that individual organ and tissue dosesare of comparable magnitude to the averagewhole-body dose.
Species-specific considerations
The high concentration ratios for freshwater fishmake the exposure of freshwater fish appropriatefor specific consideration.
Plant uptake in K-deficient areas or areas withorganic soils subject to wet deposition is also ofpotential importance.
Uptake in animals grazing such areas also needs tobe considered.
CC
Environment Agency Radionuclides Handbook70
Name
Radioactivehalf-life
Parent
Depleted uranium
4.46 x 109 years
N/A
Symbol
Principal decaymode
Daughter
Depleted uranium
Alpha
U-234 [R]
Origin
Grouping
Detection
Primordial
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production
• By removal of much but not all uranium-235 from uranium ore through theproduction of uranium hexafluoride, followed by conversion to other chemicalforms, e.g. uranium oxide or uranium metal
Uses• Use as tank armour and armour piercing projectiles• As a material for radiation shielding
Modes Land • From military testing or application on the battlefield
of Air • As an aerosol from military testing or application on the battlefield
release Water • Not generally released to water
Speciation
Uranium can exist in any one of four oxidationstates, with the +4 state being favoured inreducing conditions and the +6 state in oxidisingconditions.
Uranium forms a wide range of halide and oxidecompounds. The hydroxide and carbonate are alsoknown, and uranium can participate in theformation of organic complexes.
U is a ‘chemical’ problem rather than a‘radiotoxicity’ problem.
Analogue species
Depleted U is uranium in which the proportion ofU-235 is reduced, typically by a factor of 3 or 4.However, its chemical characteristics areunchanged.
For this reason, there is no requirement to identifyanalogue elements (see the entry for U-238).
D
Environment Agency Radionuclides Handbook 71
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Uranium is not stronglyadsorbed to soils.
However, its behaviour is redoxsensitive and it can accumulatein reducing horizons.
In general, it is stronglyexcluded from plants.
Aquatic
Uranium behaves conservativelyin aqueous environments.
It is not strongly accumulatedby aquatic organisms.
Atmospheric
U-238 released to atmospherewould be expected to disperseas an aerosol.
Oxide forms would dominate ifthe release was due tobattlefield activities.
Environmental sink
Depleted U entering theenvironment due to humanactivities may be mobile,migrating through the aqueousenvironment.
Intake and uptake routes
In general, uranium is strongly excluded from plants, although graincan show greater accumulation of uranium than other plant types.
Intakes from plant material and in soil are likely to be of comparableimportance for animals.
Uranium is not very bioavailable to animals -- the fractionalgastrointestinal absorption is typically 1-%2 %. Mineral bone is theprincipal site of accumulation.
Concentration ratios relative to water are about 10 for freshwaterand marine fish and crustaceans. Concentration ratios for molluscscan be a little higher (~30) and values ~100 are typical of marineplants.
Dose effects/dosimetry
Depleted uranium is primarily an alpha emitter.
Activity deposited on the outer layers of organisms(e.g. skin) will therefore be of little radiologicalconsequence.
Therefore, depleted uranium is of greatestpotential significance when internally incorporatedin organs and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerations
D
Environment Agency Radionuclides Handbook72
Name
Radioactivehalf-life
Parent
Erbium-169
9.4 days
N/A
Symbol
Principal decaymode
Daughter
Er-169
Beta
Tm-169
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses • No significant uses outside research activities
Modes Land • During treatment and disposal of spent fuel
of Air • During treatment and disposal of spent fuel
release Water • During treatment and disposal of spent fuel
Speciation
Erbium is a rare-earth element that shows anoxidation state of +3.
As such, erbium forms compounds with hydrogen,oxygen and the halides. It also forms stablecomplexes.
Analogue species
The rare earth elements (Ce, Pr, Nd, Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) exhibit similarchemical, biochemical and biogeochemicalcharacteristics. However, these characteristicschange systematically in the group with increasingatomic number. Cerium is one of the best-studiedmembers of the group.
Analogies with other members and with higheractinides, such as Am, can be useful.
E
Environment Agency Radionuclides Handbook 73
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Er-169 is highly particle reactive,and hence would remain boundto soil particles and on thesurfaces of plants.
Transfers from plant to soil andbulk movement of soils wouldbe the main transportmechanisms.
Aquatic
Er-169 is highly particle reactive.It is likely to bind to suspendedsediments close to its point ofdischarge.
It may be rapidly lost bydeposition from the watercolumn to sediments.
Atmospheric
If Er-169 was released to theatmosphere, it would be as anaerosol.
Environmental sink
The short half-life and highparticle reactivity of Er-169mean that it is likely to decayclose to its site of deposition interrestrial environments.
In aquatic environments,bottom sediments close to thesource of release may form animportant sink.
Intake and uptake routes
Er-169 is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically <0.001. Any Er-169 that isabsorbed is mainly deposited in the liver and skeleton.
Intake by terrestrial animals is likely to be mainly the ingestion of Er-169 present on the exterior surfaces of plants or deposited on soil.
Very little uptake from the gastrointestinal tract is anticipated, exceptperhaps in pre-weaned animals.
In the aquatic environment, uptake by fish and invertebrates ismainly direct from the water rather than food. Uptake by aquaticplants is likely to be by surface adsorption.
Dose effects/dosimetry
Er-169 is primarily a beta emitter, with negligibleemission of gamma rays.
This means that only superficial tissues (to a depthof a few millimetres) will be exposed from externalirradiation.
Internal irradiation will be limited because of thelow bioavailability of Er-169.
Species-specific considerations
In mammals and birds, the walls of thegastrointestinal tract are likely to receivesubstantially higher doses than other organs andtissues.
E
Environment Agency Radionuclides Handbook74
Name
Radioactivehalf-life
Parent
Fluorine-18
110 minutes
N/A
Symbol
Principal decaymode
Daughter
F-18
Beta [gamma]
O-18
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Irradiation of stable precursors with neutrons in a nuclear reactor or cyclotron
Uses • In medical diagnosis using positron emission tomography
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Fluorine is a halogen element that shows a singleoxidation state of -1.
It is extremely reactive and forms compounds withmost other elements, with the exception of thenoble gases.
Analogue species
Although fluorine could be considered analogousto chlorine and iodine, this is of little relevance tothe environmental behaviour of F-18 because of itsvery short radioactive half-life.
F
Environment Agency Radionuclides Handbook 75
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Direct discharges of F-18 to theterrestrial environment wouldnot be expected to occur.
Aquatic
Discharges to sewers couldoccur. However, the F-18 woulddecay almost completely duringits transport through the sewersystem.
Atmospheric
F-18 could be released toatmosphere at the time of itsproduction.
With a half-life of 110 minutes,it could be dispersed downwindover a distance of up to about30 km.
Environmental sink
Because of its very shortradioactive half-life, the primaryenvironmental sink for F-18 isradioactive decay.
Intake and uptake routes
Fluorine is not highly accumulated by plants from soils.
Although some uptake could occur, the very short half-life of F-18means that external plant contamination from atmosphericdeposition or submersion in the plume is likely to be of greatestinterest.
For animals, inhalation is likely to be the main route.
Fluorine is rapidly absorbed from both the respiratory andgastrointestinal tracts, and is then rapidly and efficiently deposited incalcified tissues
Dose effects/dosimetry
F-18 is a beta-gamma emitter.
External gamma irradiation is likely to be ofgreatest significance, although the very short half-life of F-18 will limit the total dose.
Species-specific considerations
No major species-specific considerations
F
Environment Agency Radionuclides Handbook76
Name
Radioactivehalf-life
Parent
Iron-59
44.5 days
N/A
Symbol
Principal decaymode
Daughter
Fe-59
Beta [gamma]
Co-59
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses • Investigations of iron metabolism in the spleen
Modes Land • Sewage sludge application to land
of Air • Not generally released to air
release Water • Could be released to sewers
Speciation
Iron is a transition metal that shows a number ofoxidation states, of which +2 and +3 are the mostimportant.
Of these, the +2 state is the most stable.
Iron forms a number of simple (e.g. sulphate,nitrate) and organometallic compounds.
Analogue species
Because Fe is an essential element for a widevariety of biota, it is most appropriately consideredin its own right rather than as an analogue ofother transition metals.
F
Environment Agency Radionuclides Handbook 77
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Because of the short radioactivehalf-life of Fe-59, deposition onplants will be of much greaterimportance than uptake fromsoil.
As Fe is highly particle reactive,the bulk movement of soils willbe the main transportmechanism
Aquatic
Because Fe-59 is highly particlereactive, it will adsorb stronglyto suspended sediments andmigrate to bottom sediments bydeposition of particles.
Atmospheric
If Fe-59 is released to theatmosphere, it is likely to be asan aerosol.
Environmental sink
In the terrestrial environment,Fe-59 will decay mainly close toits site of deposition.
In the aquatic environment, Fe-59 will either decay in the watercolumn or in depositedsediment.
Intake and uptake routes
In the terrestrial environment, Fe-59 will mainly be present on theexternal surfaces of plants. Contamination on plants may be ingestedby animals.
Bioavailability of Fe-59 to animals depends both on chemical formand iron concentration. Fractional gastrointestinal absorption istypically ~10 %.
In mammals and birds, uptake from the gastrointestinal tract willresult in accumulation in the liver, spleen and other soft tissues.
Concentration ratios in freshwater and marine organisms relative towater range from a few hundred to more than 10,000 and there areno strong distinctions between types.
Dose effects/dosimetry
Fe-59 emits two gamma rays with high yield andenergies above 1 MeV.
Therefore, external irradiation from a dispersingplume and from ground deposits can be ofimportance.
Uptake in plants is of little significance fordosimetric purposes, but uptake and retention inlarger animals could result in a substantialcontribution from internal dose.
Species-specific considerations
Special consideration should be given tofreshwater fish due to the high concentrationratios that can arise.
F
Environment Agency Radionuclides Handbook78
Name
Radioactivehalf-life
Parent
Gallium-67
3.3 days
N/A
Symbol
Principal decaymode
Daughter
Ga-67
EC
Zn-67
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Generally produced in a cyclotron
Uses • In medical diagnostics for imaging tumours and lesions
Modes Land• Sewage sludge application to land, but would probably decay substantially before
this can occurof
Air • Not generally released to airrelease
Water • Hospital releases to sewers
Speciation
Gallium is a Group III element whose predominantoxidation state is +3.
Some compounds with an oxidation state of +1are known, but these are relatively unstable.
Gallium forms compounds with the halides,oxygen and sulphur.
Analogue species
The are no obvious analogues for theenvironmental behaviour of Ga.
G
Environment Agency Radionuclides Handbook 79
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Because of its short radioactivehalf-life, deposition on plantswill be of much greaterimportance than uptake fromsoil.
Ga-67 would be expected to bepresent as externalcontamination of plant surfaces.
Aquatic
Little is known of the dispersionof Ga-67 in aquaticenvironments.
Atmospheric
If Ga-67 is released toatmosphere, it is likely to be asan aerosol.
Environmental sink
The short half-life of Ga-67means that it will decay interrestrial environments close toits point of deposition.
It is unlikely to disperse overlong distances in aquaticenvironments before it decays.
Intake and uptake routes
Little biotic transfer of Ga-67 is likely.
Ga-67 would be expected to be present as external contamination ofplant surfaces and not subject to significant gastrointestinalabsorption.
Dose effects/dosimetry
Ga-67 mainly emits moderately low energygamma emissions.
However, in view of its low bioavailability, externalirradiation may be the main route of exposure ofbiota.
Species-specific considerations
As biotic availability is thought to be low, there areno major species-specific considerations.
G
Environment Agency Radionuclides Handbook80
Name
Radioactivehalf-life
Parent
Tritium
12.4 years
N/A
Symbol
Principal decaymode
Daughter
H-3
Beta
He-3
Origin
Grouping
Detection
Cosmogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Through cosmic ray interactions in the upper atmosphere• Neutron irradiation of lithium-6• As a fission product in nuclear reactors
Uses• As a tracer in biological and environmental studies• As a component in nuclear weapons• As an agent in luminous paints for various applications
ModesLand • Deposition from fallout from weapons tests or a nuclear accident
ofAir • Fallout from weapons tests or a nuclear accident
releaseWater • Natural atmospheric processes
• Liquid discharges from nuclear facilities
Speciation
Hydrogen occurs freely in nature as H2, butcombines with most elements to form hydrides.
Hydrogen is a major component of most organicmolecules and thus tritium can exchange withhydrogen-1 and become bound to suchmolecules.
In the environment, water is by far the mostimportant hydrogen-containing compound.
Analogue species
There is no appropriate analogue for H, nor is oneneeded, as the environmental behaviour of variousforms of H has been extensively studied.
H
Environment Agency Radionuclides Handbook 81
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
H-3 disperses in the terrestrialenvironment in flows of surfaceand ground waters.
Some conversion from tritiatedwater to OBT (organicallybound tritium) occurs in plants.
Aquatic
Cosmogenically produced H-3mixes with surface water bodiesthroughout the world.
In general, H-3 is highlyconservative and is rapidlydispersed.
Aquatic organisms canaccumulate H-3 either astritiated water, or followingconversion in the environmentasOBT.
Atmospheric
H-3 can be dispersed in theatmosphere as water vapour,elemental hydrogen or as acomponent of other gases, suchas methane.
It is ubiquitously present inwater vapour from cosmogenicproduction.
Environmental sink
Ocean waters are the main sinkfor H-3.
These waters exchange H-3with the atmosphere, so theenvironmental sink is bestconsidered as the two together.
Intake and uptake routes
H-3 is readily taken up by plants.
Some conversion from tritiated water to OBT occurs in plants.
In animals, uptake and retention is mainly of tritiated water, forexample from plants and drinking water.
Aquatic organisms take up H-3 by exchange from the surroundingwater and through the food chain.
Dose effects/dosimetry
H-3 is a soft beta emitter and is generally relativelyuniformly distributed throughout all body tissues.
Thus, doses to individual tissues are generally ofsimilar magnitude to average whole-body doses.
Species-specific considerations
As H-3 is ubiquitously present in water in nearly allbiota, there are no major species-specificconsiderations.
H
Environment Agency Radionuclides Handbook82
Name
Radioactivehalf-life
Parent
Iodine-123
13.2 hours
N/A
Symbol
Principal decaymode
Daughter
I-123
EC
Te-123 [R]
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses • Biochemical analyses in the biological and life sciences
ModesLand • Sewage sludge application to land, but would probably decay away before this can occur
of Air• Not generally released to air, but some releases of volatile iodine compounds may
occur from sewage sludgerelease
Water • Hospital releases to sewers
Speciation
Iodine is a halogen element that exhibits anumber of stable oxidation states.
Two of the most important of these are the -1(iodide) and +5 (iodate) compounds.
Iodine can also take part in the formation oforganic complexes.
Analogue species
There are chemical similarities between F, Cl, Brand I.
However, I is an essential trace element that hasspecific biochemical roles and it has beenextensively studied.
Therefore, there is no need to rely on analogues tocharacterise its environmental behaviour.
I
Environment Agency Radionuclides Handbook 83
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
I-123 has a very short half-life.Following deposition, it willmainly be present on theexternal surfaces of plants.
As iodine is not particularlyparticle reactive, I-123 willmigrate in surface orgroundwaters through theterrestrial environment.
Aquatic
Because iodine is notparticularly particle reactive, itwill disperse freely in aquaticsystems, although some bindingto sediments can be expected.
Atmospheric
Iodine released to theatmosphere may disperse as avapour of the element, as anaerosol or as methyl iodide.
Elemental iodine and aerosolparticles are efficiently depositedto surfaces; this is not the casefor methyl iodide.
Environmental sink
The very short half-life of I-123means that it mainly decays asit disperses through theenvironment.
Iodine only exhibits a limiteddegree of sorption to mineralsolids, but it can have a highaffinity for organic matter.
Intake and uptake routes
I-123 will mainly be present on the external surfaces of plants, withsome translocation to inner plant parts.
It is highly bioavailable, being completely absorbed from thegastrointestinal tract of mammals and birds.
Although very short-lived, its half-life is long enough for it to betranslocated to the thyroid.
Iodine is only concentrated to a limited degree in most freshwaterand marine organisms, with the exception of marine plants (e.g.some algae and seaweeds).
Dose effects/dosimetry
I-123 emits mainly relatively low energy gammarays.
Because of its high degree of concentration in thethyroids of mammals and birds, radiation dose tothe thyroid is of primary interest, although gammadoses to other organs may be significant.
At lower doses, thyroid cancer would be the effectof particular interest but, at very high doses,hypothyroidism might occur.
Species-specific considerations
No major species-specific considerations, althoughit should be noted that uptake to the thyroid isstrongly determined by the level of stable iodinepresent in the diet.
I
Environment Agency Radionuclides Handbook84
Name
Radioactivehalf-life
Parent
Iodine-125
59.4 days
N/A
Symbol
Principal decaymode
Daughter
I-125
EC
Te-125
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Irradiation of stable nuclides in a reactor or cyclotron
Uses• Treatment of thyroid cancer• Biochemical analyses in medicine and the life sciences
Modes Land • Release from hospitals or research facilities
of Air • Release from hospitals or research facilities
release Water • Could be released to sewers
Speciation
Iodine is a halogen element that exhibits anumber of stable oxidation states.
Two of the most important of these are the -1(iodide) and +5 (iodate) compounds.
Iodine can also take part in the formation oforganic complexes.
Analogue species
There are chemical similarities between F, Cl, Brand I.
However, I is an essential trace element that hasspecific biochemical roles and it has beenextensively studied.
Therefore, there is no need to rely on analogues tocharacterise its environmental behaviour.
I
Environment Agency Radionuclides Handbook 85
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Following deposition, I-125 willmainly be present on theexternal surfaces of plants.
As iodine is not particularlyparticle reactive, I-125 presentin soils will tend to migrate insurface or groundwatersthrough the terrestrialenvironment.
Aquatic
Because iodine is notparticularly particle reactive, itwill disperse freely in aquaticsystems, although some bindingto sediments can be expected.
Atmospheric
Iodine released to theatmosphere may disperse as avapour of the element, as anaerosol or as methyl iodide.
Whereas elemental iodine andaerosol particles are efficientlydeposited to surfaces, this is notthe case for methyl iodide.
Environmental sink
I-125 mainly decays as itdisperses through theenvironment.
Iodine only exhibits a limiteddegree of sorption to mineralsolids, but it can have a highaffinity for organic matter.
Intake and uptake routes
I-125 will mainly be present on the external surfaces of plants, withsome translocation to inner plant parts.
It is highly bioavailable, being completely absorbed from thegastrointestinal tract of mammals and birds.
I-125 entering the systemic circulation of mammals and birds istranslocated to the thyroid.
Iodine is only concentrated to a limited degree in most freshwaterand marine organisms, with the exception of marine plants (e.g.some algae and seaweeds).
Dose effects/dosimetry
I-125 emits low energy photons and Augerelectrons (see Glossary).
Because of its high degree of concentration in thethyroids of mammals and birds, radiation dose tothe thyroid is of primary interest.
At lower doses, thyroid cancer would be the effectof particular interest but, at very high doses,hypothyroidism might occur.
Species-specific considerations
No major species-specific considerations, althoughit should be noted that uptake to the thyroid isstrongly determined by the level of stable iodinepresent in the diet.
I
Environment Agency Radionuclides Handbook86
Name
Radioactivehalf-life
Parent
Iodine-129
1.57 x 107 years
N/A
Symbol
Principal decaymode
Daughter
I-129
Beta
Xe-129
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • As a result of fission processes in a nuclear reactor
Uses • No significant uses outside research activities
Modes Land• Deposition following historic atmospheric nuclear weapons tests• Release from nuclear facilities
ofAir
• Releases during historic nuclear weapons test• Release from nuclear facilities
releaseWater • Liquid discharges from nuclear facilities
Speciation
Iodine is a halogen element that exhibits anumber of stable oxidation states.
Two of the most important of these are the -1(iodide) and +5 (iodate) compounds.
Iodine can also take part in the formation oforganic complexes.
Analogue species
There are chemical similarities between F, Cl, Brand I.
However, I is an essential trace element that hasspecific biochemical roles and it has beenextensively studied.
Therefore, there is no need to rely on analogues tocharacterise its environmental behaviour.
I
Environment Agency Radionuclides Handbook 87
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Following deposition, I-129 willmainly be present on theexternal surfaces of plants.
As iodine is not particularlyparticle reactive, I-129 presentin soils will tend to migrate insurface or groundwatersthrough the terrestrialenvironment.
Aquatic
Because iodine is notparticularly particle reactive, itwill disperse freely in aquaticsystems, although some bindingto sediments can be expected.
Atmospheric
Iodine released to theatmosphere may disperse as avapour of the element, as anaerosol or as methyl iodide.
Whereas elemental iodine andaerosol particles are efficientlydeposited to surfaces, this is notthe case for methyl iodide.
Environmental sink
I-129 becomes widely dispersedin the worldís oceans.
In the very long term, theremay be some translocation ofthis I-129 to organic-richbottom sediments.
Intake and uptake routes
I-129 will mainly be present on the external surfaces of plants, withsome translocation to inner plant parts.
It is highly bioavailable, being completely absorbed from thegastrointestinal tract of mammals and birds, following ingestion ofcontaminated foodstuffs and drinking water.
I-129 entering the systemic circulation of mammals and birds istranslocated to the thyroid.
Iodine is only concentrated to a limited degree in most freshwaterand marine organisms, with the exception of marine plants (e.g.some algae and seaweeds).
Dose effects/dosimetry
I-129 emits beta particles, low gamma rays andAuger electrons (see Glossary).
Because of its high degree of concentration in thethyroids of mammals and birds, radiation dose tothe thyroid is of primary interest.
Because of its very low specific activity, there is nopossibility of delivering high doses to the thyroid,so the potential induction of thyroid cancer is theonly effect that could be of interest.
Species-specific considerations
No major species-specific considerations, althoughit should be noted that uptake to the thyroid isstrongly determined by the level of stable iodinepresent in the diet.
I
Environment Agency Radionuclides Handbook88
Name
Radioactivehalf-life
Parent
Iodine-131
8.02 days
N/A
Symbol
Principal decaymode
Daughter
I-131
Beta [gamma]
Xe-131
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • As a result of fission processes in a nuclear reactor
Uses• Treatment of thyroid and (sometimes) bone cancer• Biochemical analyses in medicine and the life sciences
Modes Land• Deposition following a nuclear accident• Release from hospitals or nuclear facilities
ofAir • Released to air following a nuclear accident
releaseWater • Leaching from surface soils to groundwaters
Speciation
Iodine is a halogen element that exhibits anumber of stable oxidation states.
Two of the most important of these are the -1(iodide) and +5 (iodate) compounds.
Iodine can also take part in the formation oforganic complexes.
Analogue species
There are chemical similarities between F, Cl, Brand I.
However, I is an essential trace element that hasspecific biochemical roles and it has beenextensively studied.
Therefore, there is no need to rely on analogues tocharacterise its environmental behaviour.
I
Environment Agency Radionuclides Handbook 89
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Following deposition, I-131 willmainly be present on theexternal surfaces of plants.
As iodine is not particularlyparticle reactive, I-131 presentin soils will tend to migrate insurface or groundwatersthrough the terrestrialenvironment.
Aquatic
Because iodine is notparticularly particle reactive, itwill disperse freely in aquaticsystems, although some bindingto sediments can be expected.
Atmospheric
Iodine released to theatmosphere may disperse as avapour of the element, as anaerosol or as methyl iodide.
Whereas elemental iodine andaerosol particles are efficientlydeposited to surfaces, this is notthe case for methyl iodide.
Environmental sink
I-131 mainly decays as itdisperses through theenvironment.
Iodine only exhibits a limiteddegree of sorption to mineralsolids, but it can have a highaffinity for organic matter.
Intake and uptake routes
I-131 will mainly be present on the external surfaces of plants, withsome translocation to inner plant parts.
It is highly bioavailable, being completely absorbed from thegastrointestinal tract of mammals and birds.
Although short-lived, its half-life is long enough for it to betranslocated to the thyroid.
Iodine is only concentrated to a limited degree in most freshwaterand marine organisms, with the exception of marine plants (e.g.some algae and seaweeds).
Dose effects/dosimetry
I-131emits both beta particles and gamma rays.
Because of its high degree of concentration in thethyroids of mammals and birds, radiation dose tothe thyroid is of primary interest.
At lower doses, thyroid cancer would be the effectof particular interest but, at very high doses,hypothyroidism might occur.
Species-specific considerations
No major species-specific considerations, althoughit should be noted that uptake to the thyroid isstrongly determined by the level of stable iodinepresent in the diet.
I
Environment Agency Radionuclides Handbook90
Name
Radioactivehalf-life
Parent
Indium-111
2.8 days
N/A
Symbol
Principal decaymode
Daughter
In-111
EC
Cd-111
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor• Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses • In medical diagnostics as a tool for studying the brain
Modes Land• Sewage sludge application to land, but would probably decay substantially before
this can occurof
Air • Not generally released to airrelease
Water • Hospital releases to sewers
Speciation
Indium is a Group III element that can showoxidation states of +1 and +3.
It forms ionic compounds with the halides (e.g.InF3) and also forms an oxide.
Indium dissolves in acids and is oxidised onheating in air.
Analogue species
No useful analogues for indium have beenidentified.
I
Environment Agency Radionuclides Handbook 91
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Little is known of theenvironmental behaviour ofindium. However, it is not anessential trace element. With itsshort half-life, In-111 is likely tobe retained on the externalsurfaces of plants.
Aquatic
No information is readilyavailable on the behaviour ofindium in aquatic environments.
Atmospheric
If In-111 is released to theatmosphere, it is likely to be asan aerosol.
Environmental sink
In terrestrial environments,In-111 is likely to decay close toits site of deposition.
In aquatic environments, it willdecay either in the watercolumn or after deposition inbottom sediments.
Intake and uptake routes
There will be little uptake of In-111 by plants.
Animals may ingest externally contaminated plants and soils.However, only limited uptake of In-111 is likely to occur (thefractional gastrointestinal absorption in rats is about 2 %).
In-111 entering the systemic circulation is deposited mainly in bonemarrow, liver kidneys and spleen.
Dose effects/dosimetry
In-111 emits mainly gamma rays.
In view of its short half-life and low bioavailability,external irradiation is likely to be of greaterimportance than internal exposure of terrestrialplants and animals.
Species-specific considerations
No species-specific considerations have beenidentified.
I
Environment Agency Radionuclides Handbook92
Name
Radioactivehalf-life
Parent
Indium-113m
1.7 hours
N/A
Symbol
Principal decaymode
Daughter
In-113m
IT
In-113
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Irradiation of stable precursors with neutrons in a nuclear reactor or cyclotron
Uses• Diagnostic imaging of various parts of the body (liver, spleen, brain)• Determination of blood volume and cardiac output
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Indium is a group III element that can showoxidation states of +1 and +3.
It forms ionic compounds with the halides (e.g.InF3) and also forms an oxide.
Indium dissolves in acids and is oxidised onheating in air.
Analogue species
No useful analogues for indium have beenidentified.
I
Environment Agency Radionuclides Handbook 93
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Little is known of theenvironmental behaviour ofindium. However, it is not anessential trace element.
Aquatic
No information is readilyavailable on the behaviour ofindium in aquatic environments.
Atmospheric
If In-113m is released to theatmosphere, it is likely to be asan aerosol.
Environmental sink
In terrestrial environments, In-113m is likely to decay closeto its site of deposition.
In aquatic environments, it willdecay either in the watercolumn or after deposition inbottom sediments.
Intake and uptake routes
There will be little uptake of In-113m by plants.
Animals may ingest externally contaminated plants and soils.However, only limited uptake of In-113m is likely to occur (thefractional gastrointestinal absorption in rats is ~2 %).
In-113m entering the systemic circulation is deposited mainly inbone marrow, liver kidneys and spleen.
Dose effects/dosimetry
In-113m emits gamma rays of energy 0.39 MeV.
In view of its very short half-life and lowbioavailability, external irradiation is likely to be ofgreater importance than internal exposure ofterrestrial plants and animals.
Species-specific considerations
No species-specific considerations have beenidentified.
I
Environment Agency Radionuclides Handbook94
Name
Radioactivehalf-life
Parent
Potassium-40
1.3 x 109 years
N/A
Symbol
Principal decaymode
Daughter
K-40
Beta
Ca-40
Origin
Grouping
Detection
Primordial
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Naturally during the formation of the universe
Uses • No specific uses outside research activities
Modes Land • Present in all soils and rocks
of Air • Not generally released to air
release Water • Leaching via infiltration through to groundwater
Speciation
Potassium is an alkali metal whose chemicalbehaviour is determined by the properties of theK+ ion.
Most of the compounds of potassium are ionic innature, although more complex species can beformed.
Potassium reacts extremely vigorously with water,oxygen and halogens.
Analogue species
K is a chemical analogue of Cs.
However, as K is an essential element for all biota,except possibly a few bacteria, it is moreappropriate to consider Cs by analogy with K thanvice versa.
K
Environment Agency Radionuclides Handbook 95
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Little is known of theenvironmental behaviour ofindium. However, it is not anessential trace element.
Aquatic
No information is readilyavailable on the behaviour ofindium in aquatic environments.
Atmospheric
If In-113m is released to theatmosphere, it is likely to be asan aerosol.
Environmental sink
In terrestrial environments, In-113m is likely to decay closeto its site of deposition.
In aquatic environments, it willdecay either in the watercolumn or after deposition inbottom sediments.
Intake and uptake routes
There will be little uptake of In-113m by plants.
Animals may ingest externally contaminated plants and soils.However, only limited uptake of In-113m is likely to occur (thefractional gastrointestinal absorption in rats is ~2 %).
In-113m entering the systemic circulation is deposited mainly inbone marrow, liver kidneys and spleen.
Dose effects/dosimetry
In-113m emits gamma rays of energy 0.39 MeV.
In view of its very short half-life and lowbioavailability, external irradiation is likely to be ofgreater importance than internal exposure ofterrestrial plants and animals.
Species-specific considerations
No species-specific considerations have beenidentified.
K
Environment Agency Radionuclides Handbook96
Name
Radioactivehalf-life
Parent
Krypton-79
35 hours
N/A
Symbol
Principal decaymode
Daughter
Kr-79
EC
Br-79
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron irradiation of stable precursors in a cyclotron or nuclear reactor
Uses • Sometimes used as a gaseous industrial radiotracer
Modes Land • Not generally released to land
of Air • Industrial applications could result in some releases to air
release Water • Not generally released to water
Speciation
Krypton is a noble gas and, as such, forms only alimited number of chemical compounds due to itslack of reactivity.
One such example is KrF2.
Analogue species
All the noble gases (Ne, Ar, Kr, Xe and Rn) exhibitsimilar environmental behaviour.
Rn is a special case because it is generated in theenvironment from isotopes of radium and becauseit decays to produce chemically reactive, short-lived and long-lived radioactive progeny.
For this reason, Rn should not be used as ananalogue for Kr.
K
Environment Agency Radionuclides Handbook 97
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Kr-79 is not transferredsignificantly to the terrestrialenvironment.
Aquatic
Kr-79 is not transferredsignificantly to the aquaticenvironment.
Atmospheric
Kr-79 is almost exclusivelyreleased to the atmosphere.
Its very short radioactive half-lifeand low reactivity means that itdecays almost entirely duringatmospheric transport and is nottransferred significantly to otherenvironmental media.
Environmental sink
No major sink owing to its lackof reactivity and very short half-life.
Intake and uptake routes
Kr-79 is sparingly soluble in body tissues, notably those with a highfat content. However, it is not metabolised.
Some Kr-79 will be present in the lungs in inhaled air.
Dose effects/dosimetry
Kr-79 emits mainly gamma rays, either directly oras positron-annihilation radiation.
Radiation doses arise from:
• external beta irradiation of superficial tissues ofboth plants and animals;
• irradiation of the lungs of animals fromcontained gas and internal irradiation from gasdissolved in tissues.
Species-specific considerations
Because the main consideration is externalirradiation, there are no major species-dependentconsiderations.
However, aquatic organisms, plant roots andburrowing animals will be shielded, to a greater orlesser degree, from such exposures.
K
Environment Agency Radionuclides Handbook98
Name
Radioactivehalf-life
Parent
Krypton-81
2.1 x 105 years
N/A
Symbol
Principal decaymode
Daughter
Kr-81
EC
Br-81
Origin
Grouping
Detection
Cosmogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • From the decay of cyclotron-manufactured rubidium-81• From the action of cosmic rays in the upper atmosphere
Uses • The metastable species krypton-81m is used for lung ventilation scintigraphy
Modes Land • Not generally released to land
of Air • Hospital applications could result in some releases to air
release Water • Not generally released to water
Speciation
Krypton is a noble gas and lacks reactivity; assuch, it forms only a limited number of chemicalcompounds.
One such example is KrF2.
Analogue species
All the noble gases (Ne, Ar, Kr, Xe and Rn) exhibitsimilar environmental behaviour.
Rn is a special case because it is generated in theenvironment from isotopes of radium and becauseit decays to produce chemically reactive, short-lived and long-lived radioactive progeny.
For this reason, Rn should not be used as ananalogue for Kr.
K
Environment Agency Radionuclides Handbook 99
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Kr-81 is not transferredsignificantly to the terrestrialenvironment.
Aquatic
Kr-81 is not transferredsignificantly to the aquaticenvironment.
Atmospheric
Kr-81 is almost exclusivelyreleased to, or generated in, theatmosphere.
Its low reactivity means that itdecays almost entirely in theatmosphere and is nottransferred significantly to otherenvironmental media.
Environmental sink
No major sink owing to its lackof reactivity.
Intake and uptake routes
Kr-81 is sparingly soluble in body tissues, notably those with a highfat content. However, it is not metabolised.
Some Kr-81 will be present in the lungs in inhaled air.
Dose effects/dosimetry
Kr-81 is a weak gamma emitter. Exposures aremainly by external irradiation.
Cosmogenic Kr-81 gives rise to negligible doserates to organisms compared with othercosmogenic radionuclides such as C-14.
Radiation doses arise from irradiation of the lungsof animals from contained gas and internalirradiation from gas dissolved in tissues.
Species-specific considerations
As Kr-81 is globally dispersed in the atmosphereand is not accumulated in any environmentalmedia, there are no major species-dependentconsiderations.
However, aquatic organisms, plant roots andburrowing animals will be shielded, to a greater orlesser degree, from such exposures.
K
Environment Agency Radionuclides Handbook100
Name
Radioactivehalf-life
Parent
Krypton-85
10.7 years
N/A
Symbol
Principal decaymode
Daughter
Kr-85
Beta
Rb-85
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses • No significant uses outside research activities
Modes Land • Not generally released to land
of Air • From fission reactors and reprocessing facilities
release Water • Not generally released to water
Speciation
Krypton is a noble gas and, as such, forms only alimited number of chemical compounds due to itslack of reactivity.
One such example is KrF2.
Analogue species
All the noble gases (Ne, Ar, Kr, Xe and Rn) exhibitsimilar environmental behaviour.
Rn is a special case because it is generated in theenvironment from isotopes of radium and becauseit decays to produce chemically reactive, short-lived and long-lived radioactive progeny.
For this reason, Rn should not be used as ananalogue for Kr.
K
Environment Agency Radionuclides Handbook 101
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Kr-85 is not transferredsignificantly to the terrestrialenvironment.
Aquatic
Kr-85 is not transferredsignificantly to the aquaticenvironment.
Atmospheric
Kr-85 is almost exclusivelyreleased to the atmosphere.
Its low reactivity means that itdecays almost entirely in theatmosphere and is nottransferred significantly to otherenvironmental media.
Environmental sink
No major sink owing to its lackof reactivity.
Intake and uptake routes
Kr-85 is sparingly soluble in body tissues, notably those with a highfat content. However, it is not metabolised.
Some Kr-85 will be present in the lungs in inhaled air.
Dose effects/dosimetry
Kr-85 is mainly a beta emitter, with a smallcomponent of gamma emission.
Radiation doses arise from:
• external beta irradiation of superficial tissues ofboth plants and animals;
• irradiation of the lungs of animals fromcontained gas and internal irradiation from gasdissolved in tissues.
Species-specific considerations
Because Kr-85 is not metabolised to any significantdegree, there are no major species-dependentconsiderations.
K
Environment Agency Radionuclides Handbook102
Name
Radioactivehalf-life
Parent
Lanthanum-140
1.7 days
N/A
Symbol
Principal decaymode
Daughter
La-140
Beta [gamma]
Ce-140
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses• Used in blast furnaces to measure residence times and to quantify furnace
performance
Modes Land • Could be released to land following the disposal of ashes from furnaces
of Air • Could enter the atmosphere in gaseous furnace wastes during burning
release Water • Not generally released to water
Speciation
Lanthanum is a rare earth element that shows anoxidation state of +3.
As such, lanthanum forms compounds withhydrogen, oxygen and the halides. It also formsstable complexes.
Analogue species
The rare earth elements (Ce, Pr, Nd, Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) exhibit similarchemical, biochemical and biogeochemicalcharacteristics. However, these characteristicschange systematically in the group with increasingatomic number. Cerium is one of the best-studiedmembers of the group.
Analogies with other members and higheractinides such as Am can be useful.
L
Environment Agency Radionuclides Handbook 103
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
La-140 is highly particlereactive, and hence wouldremain bound to soil particlesand on the surfaces of plants.
Transfers from plant to soil andbulk movement of soils wouldbe the main transportmechanisms.
Aquatic
La-140 is highly particlereactive. It is likely to bind tosuspended sediments andwould migrate from the watercolumn to bottom sediments bydeposition.
Atmospheric
If La-140 was released to theatmosphere, it would be as anaerosol.
Environmental sink
The very short half-life and highparticle reactivity of La-140mean that it is likely to decayclose to its site of deposition interrestrial environments.
In aquatic environments,bottom sediments close to thesource of release may form animportant sink.
Intake and uptake routes
Intake by terrestrial animals is likely to be mainly the ingestion of La-140 present on the exterior surfaces of plants or deposited on soil.
La-140 is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically <0.1 %. Any La-140 that isabsorbed is mainly deposited in the liver and skeleton.
Very little uptake from the gastrointestinal tract is anticipated, exceptperhaps in pre-weaned animals.
In the aquatic environment, uptake by fish and invertebrates ismainly direct from the water rather than food. Uptake by aquaticplants is likely to be by surface adsorption.
Dose effects/dosimetry
La-140 emits energetic gamma photons.
Because of its low bioavailability and very shorthalf-life, external irradiation is more likely to beimportant than internal exposure.
Species-specific considerations
In mammals and birds, the walls of thegastrointestinal tract are likely to receivesubstantially higher doses than other organs andtissues.
L
Environment Agency Radionuclides Handbook104
Name
Radioactivehalf-life
Parent
Manganese-54
313 days
N/A
Symbol
Principal decaymode
Daughter
Mn-54
EC
Cr-54
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Produced by irradiating stable isotopes with neutrons or protons in a nuclear
reactor or cyclotron
Uses• Used to predict the behaviour of heavy metal components in effluents from
mining waste water
Modes Land • Not generally released to land
of Air • Could enter groundwater following mining water experiments
release Water • Not generally released to air
Speciation
Manganese is a transition element of Group VIIthat can show a wide range of oxidation states.
Oxidation states +2 and +3 show the widest rangeof compounds.
Manganese forms a range of oxides, includinglower oxides (e.g. MnO) and higher oxides(manganates, e.g. MnO4
-)
Analogue species
Although Mn has some chemical, biochemical andbiogeochemical affinities with Cr, Fe and Tc, itshigh concentrations in the environment and itsimportance as an essential trace element meanthat it is not appropriate to consider it as ananalogue of any other element.
M
Environment Agency Radionuclides Handbook 105
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Mn-54 is moderately particlereactive in soils and sediments.
It also tends to react withorganic matter.
Mn distributes relativelyuniformly throughout planttissues.
Aquatic
Mn-54 is highly particle reactivein aquatic environments.
It will rapidly associate withsuspended sediments.
Atmospheric
If Mn-54 was released toatmosphere, it would be as anaerosol.
MnO2 is the most likely form.
Environmental sink
As Mn-54 has a half-life of only313 days and is moderatelyparticle reactive, it can beexpected to be retained interrestrial soils and sediments,and to decay in situ.
In the aquatic environment,Mn-54 will decay in bottomsediments close to its point ofdeposition.
Intake and uptake routes
Mn distributes relatively uniformly throughout plant tissues.
Plant concentrations are similar to soil concentrations on a dry massbasis.
Mn is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~5 %. However, it is well retained inthe body, concentrating in the liver and bone.
Very high concentration ratios relative to water are observed in allclasses of marine organisms, ranging up to 10,000 or more.
Concentration ratios in freshwater fish are rather lower, ranging upto about 500.
Dose effects/dosimetry
The main emission from Mn-54 is an energeticgamma ray.
Plants will be irradiated relatively uniformly fromexternal and internal deposits of Mn-54.
In animals, the long range of the emitted photonand significant uptake in other tissues means thatmost organs and tissues receive similar radiationdoses.
Species-specific considerations
The high concentration ratios exhibited by manyaquatic organisms may mean that these are ofparticular interest.
M
Environment Agency Radionuclides Handbook106
Name
Radioactivehalf-life
Parent
Manganese-56
2.6 hours
N/A
Symbol
Principal decaymode
Daughter
Mn-56
Beta [gamma]
Fe-56
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of stable manganese present in reactor structures
Uses • Occasionally as a radiotracer
Modes Land • Treatment and disposal of spent fuel and reactor hardware
of Air • Treatment and disposal of spent fuel and reactor hardware
release Water • Treatment and disposal of spent fuel and reactor hardware
Speciation
Manganese is a transition element of Group VIIthat can show a wide range of oxidation states.
Oxidation states +2 and +3 show the widest rangeof compounds.
Manganese forms a range of oxides, includinglower oxides (e.g. MnO) and higher oxides(manganates, e.g. MnO4
-)
Analogue species
Although Mn has some chemical, biochemical andbiogeochemical affinities with Cr, Fe and Tc, itshigh concentrations in the environment and itsimportance as an essential trace element meanthat it is not appropriate to consider it as ananalogue of any other element.
M
Environment Agency Radionuclides Handbook 107
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Mn-56 is moderately particlereactive in soils and sediments.
It also tends to react withorganic matter.
Mn distributes relativelyuniformly throughout planttissues.
Aquatic
Mn-56 is highly particle reactivein aquatic environments.
It will rapidly associate withsuspended sediments.
Atmospheric
If Mn-56 was released toatmosphere, it would be as anaerosol.
MnO2 is the most likely form.
Environmental sink
Mn-56 deposited in theterrestrial environment wouldbe expected to decay close toits point of deposition.
Mn-56 in aquatic dischargeswould decay during transit tothe surface water environmentor shortly after discharge, eitherin the water column or indeposited sediments.
Intake and uptake routes
The very short half-life of Mn-56 means that it has little opportunityfor uptake by either plants or animals.
Dose effects/dosimetry
Mn-56 is a beta-gamma emitter.
The main consideration with Mn-56 in theterrestrial environment is external irradiation.
In the aquatic environment, high external doserates could occur due to trapping in depositedsediments close to the point of discharge.
Species-specific considerations
No species-specific considerations, as the shorthalf-life of Mn-56 means that there will be littleopportunity for organisms to accumulate theradionuclide.
M
Environment Agency Radionuclides Handbook108
Name
Radioactivehalf-life
Parent
Molybdenum-99
66 hours
N/A
Symbol
Principal decaymode
Daughter
Mo-99
Beta
Tc-99m [R],Tc-99 [R]
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • During the fission process in a nuclear reactor
Uses • To produce technetium-99 for medical applications
Modes Land• During treatment and disposal of spent fuel• Sewage sludge application to land, but would probably decay away before
this can occur
ofAir
• Not generally released to air - some possible during treatment and disposalof spent fuel
releaseWater
• Not generally released to water - some possible during treatment and disposalof spent fuel
• Hospital releases to sewers
Speciation
Molybdenum is a transition metal that shows alloxidation states from -2 through to +6.
Molybdenum forms compounds with thehalogens, oxygen and sulphur.
It readily forms complexes with a wide range ofatoms, most notably oxygen and sulphur.
Analogue species
Molybdenum is an essential trace element.
It exhibits distinctive chemical and biochemicalbehaviour and it is inappropriate to identify ananalogue.
M
Environment Agency Radionuclides Handbook 109
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Mo-99 is moderately particlereactive. Some transfer throughthe terrestrial environment canbe expected in surface andgroundwaters, but much willremain in situ.
Mo-99 deposited on plants willbe subject to a limited degree offoliar absorption.
Aquatic
Molybdenum in freshwaters ismainly present as dissolvedspecies.
In seawater, both dissolved andadsorbed Mo-99 could bepresent in similar quantities.
In acid waters, Mo-99 mayattach to colloidal particles ofiron hydroxides.
Atmospheric
If Mo-99 is released toatmosphere, it is likely to be as aliquid or solid aerosol.
Environmental sink
In the terrestrial environment,Mo-99 will decay close to itspoint of deposition.
In the aquatic environment, itwill decay in the water column.
Intake and uptake routes
Although foliar absorption is thought to occur readily, the short half-life of Mo-99 will limit the degree to which it takes place.
Mo-99 is highly available to animals, with a fractional gastrointestinalabsorption of ~80 %.
Although there is some preferential uptake in the skeleton, most Mo-99 will be relatively uniformly distributed throughout soft tissues.
Concentration ratios for Mo relative to water are 10-100 in marineplants, around 1,000 in freshwater plants, from 1 to 100 in marinemolluscs and around 10 in marine and freshwater fish.
Dose effects/dosimetry
Mo-99 will be present with Tc-99m in theenvironment.
Beta and gamma emissions from these tworadionuclides will generally give rise to relativelyuniform internal whole-body exposures of all typesof biota.
External exposures from deposited Mo-99 andassociated Tc-99m may also be of somesignificance in the terrestrial environment.
Species-specific considerations
Tc-99m produced from Mo-99 decaying in thebodies of mammals and birds may have atendency to translocate to the thyroid, followingpathways of iodine metabolism.
However, its short half-life and the inability of thethyroid to utilise it for hormone production willlimit the significance of this pathway.
M
Environment Agency Radionuclides Handbook110
Name
Radioactivehalf-life
Parent
Sodium-22
2.6 years
N/A
Symbol
Principal decaymode
Daughter
Na-22
Beta [gamma]
Ne-22
Origin
Grouping
Detection
Cosmogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses • In medicine as a radiotracer and for diagnostic purposes
Modes Land • Sewage sludge application to land
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Sodium is an alkali metal whose chemicalbehaviour is determined by the properties of theNa+ ion.
Most of the compounds of sodium are ionic innature, although more complex species can beformed.
Sodium reacts extremely vigorously with water,oxygen and halogens.
Analogue species
Na is an essential element for animals, but is lessimportant for plants.
Its chemistry, biochemistry and biogeochemistryare distinct from those of the other alkali metals(e.g. K) and it is inappropriate to consider it byanalogy.
N
Environment Agency Radionuclides Handbook 111
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Sodium is moderately particlereactive.
Therefore, it can be expected toremain largely in situ, althoughsome dispersion through theterrestrial environment willoccur.
Aquatic
The dominant form of sodiumin waters is Na+, but a limiteddegree of sorption to suspendedsediments may occur.
Nevertheless, Na-22 would beexpected to behaveconservatively in aquaticsystems.
Atmospheric
If Na-22 was released to theatmosphere, it would be in theform of an aerosol.
Environmental sink
Na-22 will migrate to someextent in the soil column andfrom terrestrial deposits tosurface water bodies beforedecaying.
However, the degree ofmovement will differsubstantially in Na-rich and Na-deficient soils.
In aquatic systems, Na-22 willdecay mainly in the watercolumn.
Intake and uptake routes
In terrestrial environments, high concentrations will occur in plantsfrom active uptake.
High concentrations may also occur in animals following ingestion ofcontaminated plant material or drinking water.
Gastrointestinal absorption is virtually complete.
Concentrations of Na-22 in plants and animals will tend to be higherin Na-deficient than in Na-rich conditions.
A relatively high degree of uptake is expected in freshwaterorganisms, but not in marine organisms.
Dose effects/dosimetry
Na-22 is a positron emitter. Thus, it emitsannihilation gamma rays of energy 0.511 MeV, aswell as a gamma ray of energy 1.275 MeV.
These gamma rays mean that Na-22 can give riseto significant external exposure.
However, its high bioavailability in terrestrial andfreshwater environments means that internalexposures are likely to be more important.
Species-specific considerations
Terrestrial plants and animals living in Na-deficientconditions need to be given special consideration.
Freshwater organisms in environments in whichthe Na-22 is not rapidly dispersed and dilutedshould also be given special consideration.
N
Environment Agency Radionuclides Handbook112
Name
Radioactivehalf-life
Parent
Sodium-24
15 hours
N/A
Symbol
Principal decaymode
Daughter
Na-24
Beta [gamma]
Mg-24
Origin
Grouping
Detection
Cosmogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses • In medicine as a radiotracer and for diagnostic purposes
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Sodium is an alkali metal whose chemicalbehaviour is determined by the properties of theNa+ ion.
Most of the compounds of sodium are ionic innature, although more complex species can beformed.
Sodium reacts extremely vigorously with water,oxygen and halogens.
Analogue species
Na is an essential element for animals, but is lessimportant for plants.
Its chemistry, biochemistry and biogeochemistryare distinct from those of the other alkali metals(e.g. K) and it is inappropriate to consider it byanalogy.
N
Environment Agency Radionuclides Handbook 113
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Sodium is moderately particlereactive.
Therefore, it can be expected toremain largely in situ, althoughsome dispersion through theterrestrial environment willoccur.
Aquatic
The dominant form of sodiumin waters is Na+, but a limiteddegree of sorption to suspendedsediments may occur.
Nevertheless, Na-24 would beexpected to behaveconservatively in aquaticsystems.
Atmospheric
If Na-24 was released to theatmosphere, it would be in theform of an aerosol.
Environmental sink
Na-24 will migrate to someextent in the soil column andfrom terrestrial deposits tosurface water bodies beforedecaying.
However, the very short half-lifeof Na-24 will limit the degree ofmigration.
In aquatic systems, Na-24 willdecay mainly in the watercolumn.
Intake and uptake routes
In terrestrial environments, high concentrations will occur in plantsfrom active uptake.
High concentrations may also occur in animals following ingestion ofcontaminated plant material or drinking water.
Gastrointestinal absorption is virtually complete.
Concentrations of Na-24 in plants and animals will tend to be higherin Na-deficient than in Na-rich conditions.
A relatively high degree of uptake is expected in freshwaterorganisms, but not in marine organisms.
Dose effects/dosimetry
Na-24 emits a beta particle and gamma rays withenergies of 1.37 and 2.75 MeV.
These gamma rays mean that Na-24 can give riseto significant external exposure.
Because of its very short half-life, externalexposure may be of more significance thaninternal exposure.
However, the high bioavailability of Na-24 meansthat internal exposures must not be neglected.
Species-specific considerations
Terrestrial plants and animals living in Na-deficientconditions need to be given special consideration.
Freshwater organisms in environments in whichthe Na-24 is not rapidly dispersed and dilutedshould also be given special consideration.
N
Environment Agency Radionuclides Handbook114
Name
Radioactivehalf-life
Parent
Niobium-94
2.03 x 104 years
N/A
Symbol
Principal decaymode
Daughter
Nb-94
Beta [gamma]
Mo-94
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron irradiation of niobium-93 present in reactor components
Uses • As a laboratory source of gamma rays
Modes Land • Treatment and disposal of spent fuel and reactor hardware
of Air • Treatment and disposal of spent fuel and reactor hardware
release Water • Treatment and disposal of spent fuel and reactor hardware
Speciation
The chemistry of niobium is dominated by the +5oxidation state.
It forms halide compounds that hydrolyse easily toform niobium oxide, Nb2O5.
The niobate ion (NbO3-) can also be formed by
reducing niobium oxide.
Niobium can also take part in the formation ofcolloids and organic complexes.
Analogue species
Na is an essential element for animals, but is lessimportant for plants.
Its chemistry, biochemistry and biogeochemistryare distinct from those of the other alkali metals(e.g. K) and it is inappropriate to consider it byanalogy.
N
Environment Agency Radionuclides Handbook 115
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Nb-94 is moderately particlereactive in terrestrial soils. It isstrongly excluded from plants.
The little Nb-94 that is taken upby roots is mainly retained thereand not translocated to aboveground tissues.
Aquatic
Nb-94 is highly particle reactivein aquatic sediments.
It will rapidly associate withsuspended sediments.
Atmospheric
If Nb-94 is released toatmosphere, it is likely to be asan aerosol.
Environmental sink
In terrestrial environments, Nb-94 will mainly be retained inthe soil column.
In aquatic environments, mostNb-94 is likely to becomeadsorbed to suspendedsediments and hence migrate tobottom sediments.
Intake and uptake routes
Nb-94 is not very bioavailable to plants.
Animal intakes are likely to result mainly from the ingestion of soil orof contaminated drinking water.
The fractional gastrointestinal absorption is ~0.2 %, except in pre-weaned animals. Much of the uptake is deposited in mineral bone,with the remainder widely dispersed amongst soft tissues.
Concentration ratios relative to water are ~30 for freshwater andmarine fish. Concentration ratios for marine molluscs and crustaceansare typically ~200 and ~1,000, respectively. Concentration ratios formarine plants are also ~1,000.
Dose effects/dosimetry
Nb-94 is a beta-gamma emitter.
External exposure is likely to be of greaterimportance than internal exposure in manycontexts, notably in the terrestrial environment.
Species-specific considerations
Special consideration should be given to marinemolluscs, crustaceans and plants in view of theconcentration ratios for these species.
N
Environment Agency Radionuclides Handbook116
Name
Radioactivehalf-life
Parent
Niobium-95
35 days
Zr-95
Symbol
Principal decaymode
Daughter
Nb-95
Beta [gamma]
Mo-95
Origin
Grouping
Detection
Radiogenic
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Produced during fission in a nuclear reactor• From the decay of Zr-95, also an important fission product
Uses • No significant uses outside research activities
ModesLand • During treatment and disposal of spent fuel
ofAir • Not generally released to air
release Water• During treatment and disposal of spent fuel• Liquid discharges from nuclear facilities
Speciation
The chemistry of niobium is dominated by the +5oxidation state.
It forms halide compounds that hydrolyse easily toform niobium oxide, Nb2O5.
The niobate ion (NbO3-) can also be formed by
reducing niobium oxide.
Niobium can also take part in the formation ofcolloids and organic complexes.
Analogue species
Zr and Nb have been quite extensively studied.
They exhibit considerable similarities in theirenvironmental behaviour.
N
Environment Agency Radionuclides Handbook 117
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Nb-95 is moderately particlereactive in terrestrial soils. It isstrongly excluded from plants.
The little Nb-95 that is taken upby roots is mainly retained thereand not translocated to aboveground tissues.
Aquatic
Nb-95 is highly particle reactivein aquatic sediments.
It will rapidly associate withsuspended sediments.
Atmospheric
If Nb-95 is released toatmosphere, it is likely to be asan aerosol.
Environmental sink
In terrestrial environments, Nb-95 will mainly be retained inthe soil column.
In aquatic environments, mostNb-95 is likely to becomeadsorbed to suspendedsediments and hence migrate tobottom sediments.
Intake and uptake routes
Nb-95 is not very bioavailable to plants.
Animal intakes are likely to result mainly from the ingestion of soil orof contaminated drinking water.
The fractional gastrointestinal absorption is ~0.2 %, except in pre-weaned animals. Much of the uptake is deposited in mineral bone,with the remainder widely dispersed amongst soft tissues.
Concentration ratios relative to water are ~30 for freshwater andmarine fish. Concentration ratios for marine molluscs and crustaceansare typically ~200 and ~1,000, respectively. Concentration ratios formarine plants are also ~1,000.
Dose effects/dosimetry
Nb-95 is a beta-gamma emitter.
External exposure is likely to be of greaterimportance than internal exposure in manycontexts, notably in the terrestrial environment.
Species-specific considerations
Because of its low bioavailability and theimportance of external irradiation, there are nomajor species-specific considerations.
However, special consideration should be given tobenthic aquatic organisms located close to sourcesof aquatic release, as these may be exposed tohigh Nb-95 concentrations in depositedsediments.
N
Environment Agency Radionuclides Handbook118
Name
Radioactivehalf-life
Parent
Nickel-59
7.6 x 104 years
N/A
Symbol
Principal decaymode
Daughter
Ni-59
Beta
Co-59
Origin
Grouping
Detection
Cosmogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production
• Fission neutron irradiation of metallic nuclear reactor components(e.g. Cr, Mn, Fe, Co, Ni)
• Cosmic ray interactions in the upper atmosphere
Uses • No specific uses outside research activities
ModesLand • Treatment and disposal of spent fuel hardware
of Air• Treatment and disposal of spent fuel hardware• Trace amounts due to fallout from weapons testing
releaseWater • Treatment and disposal of spent fuel hardware
Speciation
Nickel is a transition metal that can exist in anumber of oxidation states.
The +2 state is the most stable in terms of theproperties of the compounds for variations in pHand Eh.
Such compounds include the halides, hydroxideand carbonate.
Analogue species
There are chemical, biochemical andbiogeochemical similarities amongst a number ofthe transition metals.
However, Ni is an essential trace element in somespecies and its environmental behaviour has beenextensively studied.
Therefore, it is not necessary or appropriate to relyon analogues.
N
Environment Agency Radionuclides Handbook 119
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ni is moderately particlereactive in soils and is unlikelyto be available for uptake byplants.
Aquatic
Ni is highly particle reactive inboth freshwaters and marineenvironments.
Significant migration todeposited sediments is likely tooccur in both types ofenvironment.
Atmospheric
If Ni-59 is released to theatmosphere, it is likely to be asan aerosol.
Environmental sink
Although Ni-59 will bemoderately well retained insoils, its long half-life meansthat there will eventually besignificant transfer to aquaticenvironments by leaching anderosive processes.
In the aquatic environment,most Ni-59 is likely toeventually be present indeposited sediments, which iswhere it will mainly decay.
Intake and uptake routes
Ni-59 is not particularly bioavailable to plants.
Intakes by animals in terrestrial environments will be of Ni-59incorporated in plants, bound to soil and in drinking water.
Ni is not very bioavailable to animals, with a fractionalgastrointestinal absorption of ~5 %.
That which is not rapidly excreted becomes uniformly distributed inthe body and tenaciously retained.
Concentration ratios relative to water are typically ~100 forfreshwater and marine fish, and ~1,000 for marine plants, molluscsand crustaceans.
Dose effects/dosimetry
Ni-59 emits low energy X-rays and electrons.
This means that external irradiation is of littleimportance.
Ni-59 incorporated into organisms is distributedrelatively uniformly throughout them. Doses toindividual organs and tissues will thus be of similarmagnitude to average whole-body doses.
Species-specific considerations
No major species-specific considerations have beenidentified.
However, special consideration should be given tobenthic organisms located close to sources ofaquatic release, as these may be exposed to highNi-59 concentrations in aquatic sediments andtake up Ni-59 from those sediments.
N
Environment Agency Radionuclides Handbook120
Name
Radioactivehalf-life
Parent
Nickel-63
100 years
N/A
Symbol
Principal decaymode
Daughter
Ni-63
Beta
Cu-63
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Fission neutron irradiation of metallic nuclear reactor components
(e.g. Cr, Mn, Fe, Co, Ni)
Uses • No specific uses outside research activities
ModesLand • Treatment and disposal of spent fuel hardware
of Air• Treatment and disposal of spent fuel hardware• Trace amounts due to fallout from weapons testing
releaseWater • Treatment and disposal of spent fuel hardware
Speciation
Nickel is a transition metal that can exist in anumber of oxidation states.
The +2 state is the most stable in terms of theproperties of the compounds for variations in pHand Eh.
Such compounds include the halides, hydroxideand carbonate.
Analogue species
There are chemical, biochemical andbiogeochemical similarities amongst a number ofthe transition metals.
However, Ni is an essential trace element in somespecies and its environmental behaviour has beenextensively studied.
Therefore, it is not necessary or appropriate to relyon analogues.
N
Environment Agency Radionuclides Handbook 121
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ni is moderately particlereactive in soils and little addedNi-63 is likely to remainavailable for uptake by plants.
Aquatic
Ni is highly particle reactive inboth freshwaters and marineenvironments.
Significant migration todeposited sediments is likely tooccur in both types ofenvironment.
Atmospheric
If Ni-63 is released to theatmosphere, it is likely to be asan aerosol.
Environmental sink
Although Ni-63 will bemoderately well retained insoils, its long half-life meansthat there will eventually besignificant transfer to aquaticenvironments by leaching anderosive processes.
In the aquatic environment,most Ni-63 is likely toeventually be present indeposited sediments, which iswhere it will mainly decay.
Intake and uptake routes
Ni-63 is not particularly bioavailable to plants.
Intakes by animals in terrestrial environments will be of Ni-63incorporated in plants, bound to soil and in drinking water.
Ni is not very bioavailable to animals, with a fractionalgastrointestinal absorption of around 5 %.
That which is not rapidly excreted becomes uniformly distributed inthe body and tenaciously retained.
Concentration ratios relative to water are typically ~100 forfreshwater and marine fish, and ~1,000 for marine plants, molluscsand crustaceans.
Dose effects/dosimetry
Ni-63 emits low-energy beta particles.
This means that external irradiation is of littleimportance.
Ni-63 incorporated into organisms is distributedrelatively uniformly throughout them. Doses toindividual organs and tissues will thus be of similarmagnitude to average whole-body doses.
Species-specific considerations
No major species-specific considerations have beenidentified.
However, special consideration should be given tobenthic organisms located close to sources ofaquatic release, as these may be exposed to highNi-63 concentrations in aquatic sediments andtake up Ni-63 from those sediments.
N
Environment Agency Radionuclides Handbook122
Name
Radioactivehalf-life
Parent
Neptunium-237
2.1 x 106 years
Am-241
Symbol
Principal decaymode
Daughter
Np-237
Alpha
Pa-233 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Trace quantities found in nature• Decay of americium-241 produced in a nuclear reactor
Uses • Sometimes used in neutron detection equipment
Modes Land • Treatment and disposal of spent fuel
of Air • Not generally released to air
release Water • Treatment and disposal of spent fuel
Speciation
Neptunium can exist in a number of oxidationstates, but only the +4 and +5 states are importantin environmental systems.
A variety of species in aqueous solution can beformed, depending on Eh and pH.
Analogue species
There are chemical similarities between Np and U,and also between Np and Pu.
However, the chemistry, biochemistry andbiogeochemistry of Np are complex, and neither Unor Pu can be relied upon as quantitativeanalogues for its behaviour in the environment.
N
Environment Agency Radionuclides Handbook 123
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Np-237 is moderately particlereactive in terrestrial soils andsediments.
Most Np-237 will thereforeremain in situ.
Aquatic
Np-237 is highly particlereactive in the aquaticenvironment and thereforetends to migrate to bottomsediments.
Atmospheric
Np-237 would be expected todisperse as an aerosol.
Environmental sink
Np-237 deposited in theterrestrial environment willmainly be transferred to soils,where it will tend to remain.
In aquatic systems, bottomsediments are the most likelyenvironmental sink and Np-237migration will be closelyassociated with sedimenttransport.
Intake and uptake routes
Np-237 is quite strongly excluded from plants. Much of the Np-237content of plants is likely to be due to surface contamination.
Ingestion of contaminated soil or sediment and inhalation couldcompete with ingestion of contaminated plant material as importantroutes of intake by animals.
Uptake from the gastrointestinal tract is limited (typically ~0.001),although enhanced concentrations of Np-237 may occur in the liver,kidneys and skeleton.
Concentration ratios of between 10 and 100 are typical for marineand freshwater species.
Dose effects/dosimetry
Ni-63 emits low-energy beta particles.
This means that external irradiation is of littleimportance.
Ni-63 incorporated into organisms is distributedrelatively uniformly throughout them. Doses toindividual organs and tissues will thus be of similarmagnitude to average whole-body doses.
Species-specific considerations
No major species-specific considerations have beenidentified.
However, special consideration should be given tobenthic organisms located close to sources ofaquatic release, as these may be exposed to highNi-63 concentrations in aquatic sediments andtake up Ni-63 from those sediments.
N
Environment Agency Radionuclides Handbook124
Name
Radioactivehalf-life
Parent
Oxygen-15
122 seconds
N/A
Symbol
Principal decaymode
Daughter
O-15
Beta
N-15
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced by irradiating stable precursors in a cyclotron
Uses • Used in positron emission tomography to study brain physiology and pathology
Modes Land • Not generally released to land
of Air • Could be released to air, but the very short half-life mitigates any adverse impact
release Water • Not generally released to water
Speciation
The predominant oxidation state for oxygen is -2.
It is an extremely reactive gas and is capable offorming compounds with most other elements,usually forming one or more oxides of thoseelements.
Analogue species
Oxygen is a ubiquitous element in theenvironment and is involved in a wide variety ofbiological, biochemical and biogeochemicalprocesses.
There is no appropriate analogue, but theenvironmental behaviour of the stable element hasbeen extensively studied.
O
Environment Agency Radionuclides Handbook 125
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
The half-life of O-15 is too shortfor significant transport in theterrestrial environment to occur.
Aquatic
The half-life of O-15 is too shortfor significant transport in theaquatic environment to occur.
Atmospheric
O-15 has a radioactive half-lifeof only 122 seconds. Therefore,the only potentially relevantpathway is atmospheric releaseand exposure from thedispersing plume.
Dispersion distances before theactivity is substantially depletedby radioactive decay will be nomore than a few kilometres.
Environmental sink
O-15 released to theatmosphere will decay as itdisperses.
Intake and uptake routes
The main uptake mechanism for O-15 is inhalation, although any O-15 that is absorbed by organisms will decay rapidly.
Dose effects/dosimetry
The 0.511 MeV photons from O-15 will give riseto whole-body exposure from external irradiation.
Positron emissions can also give rise to superficialexposures to organisms, but this is likely to be asecondary consideration.
Species-specific considerations
Because the main consideration is externalirradiation, there are no major species-dependentconsiderations.
However, aquatic organisms, plant roots andburrowing animals will be shielded, to a greater orlesser degree, from such exposures.
O
Environment Agency Radionuclides Handbook126
Name
Radioactivehalf-life
Parent
Phosphorus-32
14.3 days
N/A
Symbol
Principal decaymode
Daughter
P-32
Beta
S-32
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced by irradiating stable precursors in a cyclotron
Uses • Used in positron emission tomography to study brain physiology and pathology
Modes Land • Not generally released to land
of Air • Could be released to air, but the very short half-life mitigates any adverse impact
release Water • Not generally released to water
Speciation
Phosphorus is a Group V element that shows twostable oxidation states, +3 and +5.
Phosphorus forms compounds with the halides,hydrogen, oxygen and sulphur, and forms a rangeof organic acids.
Phosphorus can be obtained in a number ofallotropic forms, of which white phosphorus is themost reactive.
Analogue species
Oxygen is a ubiquitous element in theenvironment and is involved in a wide variety ofbiological, biochemical and biogeochemicalprocesses.
There is no appropriate analogue, but theenvironmental behaviour of the stable element hasbeen extensively studied.
P
Environment Agency Radionuclides Handbook 127
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Phosphorus shows only limitedparticle reactivity, and so can beexpected to move freelythrough the terrestrialenvironment, rather thanremaining in situ.
Aquatic
In aquatic ecosystems,phosphorus is present asparticulate organic phosphorus,dissolved inorganic phosphatesand dissolved organicphosphorus.
In most aquatic environments,particulate phosphorus is ingreatest abundance.
Atmospheric
If P-32 were released to theatmosphere, it would probablybe in the form of an aerosol.
Environmental sink
P-32 is sufficiently short-livedthat it will decay close to its siteof deposition in the terrestrialenvironment.
In the aquatic environment, P-32 is likely to decay mainly inthe water column, either insolution or incorporated inorganic particles.
Intake and uptake routes
P-32 deposited on land is likely to be highly available to plants, assoils typically contain only 0.65 ppm but plants contain about 1,000ppm.
It is highly available to animals, with gastrointestinal absorptionbeing almost complete.
In the short-term, phosphorus is widely distributed throughout alltissues. In the long-term, calcified tissues are the main reservoir.
In aquatic environments, very rapid uptake by organisms can beexpected, leading to concentration ratios relative to water of 10,000or more.
Dose effects/dosimetry
P-32 is a pure beta emitter.
Because of this and its high bioavailability, internalexposures will be of principal importance.
Although there may be some degree ofpreferential irradiation of calcified tissues, theeffect will be limited by the short half-life of theradionuclide.
Species-specific considerations
No major species-specific considerations have beenidentified.
P
Environment Agency Radionuclides Handbook128
Name
Radioactivehalf-life
Parent
Phosphorus-33
25.3 days
N/A
Symbol
Principal decaymode
Daughter
P-33
Beta
S-33
Origin
Grouping
Detection
Activation
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron bombardment of stable sulphur-33 in a cyclotron
Uses • In medicine as a radiotracer
Modes Land • Sewage sludge application to land
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Phosphorus is a Group V element that shows twostable oxidation states, +3 and +5.
Phosphorus forms compounds with the halides,hydrogen, oxygen and sulphur, and forms a rangeof organic acids.
Phosphorus can be obtained in a number ofallotropic forms, of which white phosphorus is themost reactive.
Analogue species
Phosphorus as phosphate is essential to all livingcells and is a component of DNA.
For this reason, it is appropriately considered in itsown right, rather than as an analogue of any otherelement.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Phosphorus shows only limitedparticle reactivity, and so can beexpected to move freelythrough the terrestrialenvironment, rather thanremaining in situ.
Aquatic
In aquatic ecosystems,phosphorus is present asparticulate organic phosphorus,dissolved inorganic phosphatesand dissolved organicphosphorus.
In most aquatic environments,particulate phosphorus is ingreatest abundance.
Atmospheric
If P-33 were released to theatmosphere, it would probablybe in the form of an aerosol.
Environmental sink
P-33 is sufficiently short-livedthat it will decay close to its siteof deposition in the terrestrialenvironment.
In the aquatic environment, P-33 is likely to decay mainly inthe water column, either insolution or incorporated inorganic particles.
Intake and uptake routes
P-33 deposited on land is likely to be highly available to plants, assoils typically contain only 0.65 ppm but plants contain about 1,000ppm.
It is highly available to animals, with gastrointestinal absorptionbeing almost complete.
In the short-term, phosphorus is widely distributed throughout alltissues. In the long-term, calcified tissues are the main reservoir.
In aquatic environments, very rapid uptake by organisms can beexpected, leading to concentration ratios relative to water of 10,000or more.
Dose effects/dosimetry
P-33 is a pure beta emitter.
Because of this and its high bioavailability, internalexposures will be of principal importance.
Although there may be some degree ofpreferential irradiation of calcified tissues, theeffect will be limited by the short half-life of theradionuclide.
Species-specific considerations
No major species-specific considerations have beenidentified.
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Environment Agency Radionuclides Handbook130
Name
Radioactivehalf-life
Parent
Protactinium-234m
1.2 minutes
Th-234
Symbol
Principal decaymode
Daughter
Pa-234m
Beta
U-234 [R]
Origin
Grouping
Detection
Radiogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Naturally in all environmental media from the decay of U-238
Uses • No specific uses outside research activities
Modes Land • Disposed uranium mill tailings
of Air • Only in circumstances where U-238/Th-234 is present in air
release Water • Only in circumstances where U-238/Th-234 is present in water
Speciation
Protactinium exists in aqueous solution in twooxidation states, +4 and +5, although the +5 statetends to be predominant.
Protactinium compounds tend to hydrolyse insolution.
Pa is not usually found in solution as a singlespecies, but appears as a mixture of complexesand hydrolysed species.
Analogue species
Pa-234m has a half-life of only 1.2 minutes andwill have little time to exhibit its environmentalchemistry.
Therefore, there is no need to identify analoguespecies.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Pa-234m would be expected tobe present at close to the sameactivity equilibrium as its parentTh-234.
Aquatic
Pa-234m would be expected tobe present at close to the sameactivity concentration as itsparent Th-234. Th is particlereactive.
Atmospheric
Pa-234m would be expected tobe present in aerosols at close tothe same activity concentrationas its parent Th-234.
Environmental sink
Pa-234m would be expected todecay close to its site ofproduction.
Intake and uptake routes
Because of its very short half-life, Pa-234m would be present in biotaat close to the same activity concentration as its parent Th-234.
Therefore, intake and uptake of Pa-234m are of little relevancecompared with intake and uptake of its parent, Th-234.
Dose effects/dosimetry
Pa-234m is mainly a beta emitter, although thereis also a small amount of gamma emission.
Therefore, it is mainly of interest as an internallyincorporated radionuclide, as it will deliver moredose than its parent Th-234.
Species-specific considerations
No species-specific considerations have beenidentified.
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Environment Agency Radionuclides Handbook132
Name
Radioactivehalf-life
Parent
Lead-210
22.3 years
Po-214
Symbol
Principal decaymode
Daughter
Pb-210
Beta
Bi-210 [R]
Origin
Grouping
Detection
Radiogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Naturally in all environmental media from the decay of U-238• By product of uranium mining and milling
Uses • Determination of the age of lake and ocean sediments
ModesLand • Fallout from atmosphere following the decay of Rn-222
of Air• From burning coal• From decay in the atmosphere of Rn-222
releaseWater • Fallout from atmosphere following the decay of Rn-222
Speciation
Lead is found predominantly in the +2 oxidationstate in environmental waters.
It exists primarily as carbonato-, hydroxy- andchloro- complexes.
Lead also forms compounds with oxygen, thehalides and various organic molecules.
Analogue species
There are similarities between the chemistry andbiochemistry of Pb and Ca.
These can be useful mainly for interpretation ofspecific observations on Pb, rather than treating Pbas behaving in a generally analogous manner toCa throughout the environment.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Pb-210 shows a very high levelof particle reactivity, and so canbe expected to remain in situ,rather than moving freelythrough the terrestrialenvironment.
Aquatic
Pb-210 is produced in aquaticsystems from the decay of Ra-226 via Rn-222 and its short-lived progeny.
Owing to its particle reactivity, itwill tend to bind to sediments.
Atmospheric
Pb-210 is produced in theatmosphere mainly from theprogeny of Rn-222. It is thensubject to deposition.
Environmental sink
In terrestrial systems, Pb-210typically decays close to its siteof production.
In aquatic systems, Pb-210tends to accumulate in bottomsediments
Intake and uptake routes
Pb-210 accumulates mainly on the external surfaces of plants, as itexhibits only a limited degree of bioavailability.
Lichens have very large surface areas per unit area of ground and canbe a major source of Pb-210 to grazing animals.
It is quite highly bioavailable to animals, with a fractionalgastrointestinal absorption ~20 % and is accumulated mainly incalcified tissues.
Aquatic biota exhibit concentration ratios relative to water of ~200 inboth marine and freshwater fish, and ~1,000 in marine molluscs,crustaceans and seaweed.
Dose effects/dosimetry
Pb-210 emits low-energy beta particles togetherwith a small amount of low energy photons.
Its short-lived daughter, Bi-210, is a pure betaemitter..
However, this then decays to Po-210, which is analpha emitter and is often a more importantcontributor to internal dose than is its ancestor Pb-210.
Species-specific considerations
Naturally occurring Pb-210 is highly accumulatedin marine organisms and in organisms such asreindeer that graze on plants with a high surfacearea per unit area of land such as lichens.
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Environment Agency Radionuclides Handbook134
Name
Radioactivehalf-life
Parent
Promethium-147
2.6 years
N/A
Symbol
Principal decaymode
Daughter
Pm-147
Beta
Sm-147 [R]
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses• As a beta source for thickness gauges• As a coating for self-luminous watch dials• Potentially as a heat source for space probes and satellites
Modes Land • Not generally released to land
of Air • Not generally released to air
release Water • Not generally released to water
Speciation
Promethium is a rare earth element that shows anoxidation state of +3, and whose compounds aretypical of other rare earth compounds.
As such, promethium forms compounds withhydrogen, oxygen and the halides.
It also forms stable complexes.
Analogue species
There are considerable similarities in the chemistry,biochemistry and biogeochemistry of all thelanthanide elements.
In particular, Ce, Sm and Eu are moderatelyextensively studied elements that are analogous toPm.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Pm-147 is highly particlereactive, and hence wouldremain bound to soil particlesand on the surfaces of plants.
Transfers from plant to soil andbulk movement of soils wouldbe the main transportmechanisms.
Aquatic
Pm-147 is highly particlereactive in the aquaticenvironment.
It is likely to bind to suspendedsediments close to its point ofdischarge and migrate lost fromthe water column by depositionof those sediments.
Atmospheric
If Pm-147 was released to theatmosphere, it would be as anaerosol and probably in oxideform.
Environmental sink
The high particle reactivity ofPm-147 mean that it is likely todecay close to its site ofdeposition in terrestrialenvironments.
In aquatic environments,bottom sediments close to thesource of release may form animportant sink.
Intake and uptake routes
Pm-147 is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically <0.001. Any Pm-147 that isabsorbed is mainly deposited in the liver and skeleton.
Intake by terrestrial animals is likely to be mainly the ingestion of Pm-147 present on the exterior surfaces of plants or deposited onsoil.
Very little uptake from the gastrointestinal tract is anticipated, exceptperhaps in pre-weaned animals.
In the aquatic environment uptake by fish and invertebrates is mainlydirect from the water rather than food. Uptake by aquatic plants islikely to be by surface adsorption.
Dose effects/dosimetry
Pm-147 is almost exclusively an emitter of low-energy beta particles.
External deposits of Pm-147 on plants and animalswill only result in irradiation of superficial outertissues, which are often unsensitive to radiationexposure.
Internal exposure will be limited by the lowbioavailability of Pm-147.
Species-specific considerations
The high uptakes in molluscs, crustaceans andaquatic plants could be important.
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Environment Agency Radionuclides Handbook136
Name
Radioactivehalf-life
Parent
Polonium-210
138 days
Bi-210
Symbol
Principal decaymode
Daughter
Po-210
Alpha
Pb-206
Origin
Grouping
Detection
Radiogenic
Natural
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Naturally in all environmental media from the decay of U-238• By product of uranium mining and milling
Uses • Source of electric power for space vehicles
ModesLand • Disposed uranium mill tailings
of Air• From burning coal• During treatment of spent fuel
releaseWater • During treatment of spent fuel
Speciation
Polonium is a Group VI element that formscompounds with the halogens, hydrogen, andoxygen to produce a range of oxides.
All polonium compounds hydrolyse in water.
Analogue species
Po-210 is the daughter of Pb-210.
Its environmental behaviour is stronglyconditioned by that of its parent.
As extensive environmental studies have beenundertaken relating to Pb-210 and Po-210, it isnot appropriate to rely on analogues.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Po-210 is formed in theterrestrial environment fromdeposited Pb-210.
Po-210 is highly particlereactive, so will tend to remainin situ rather than migrating insurface or groundwaters.
Aquatic
Po-210 is produced in aquaticsystems from the decay of Pb-210.
Owing to its particle reactivity, itwill tend to bind to sediments.
Atmospheric
Po-210 can be formed from Pb-210 in the atmosphere.
However, as the mean residencetime of dust suspended in thetroposphere is only about 15days, there is little time for itsingrowth in the atmosphere.
Environmental sink
Pb-210 typically decays close toits site of production from Pb-210.
Intake and uptake routes
Po-210 is not very available to plants.
The fractional gastrointestinal absorption of Po-210 in mammals istypically ~10 %.
Po-210 entering the systemic circulation is widely distributed in softtissues. Although it has no particular affinity for bone, it is oftenfound there in higher concentrations than in other tissues, havingbeen produced by decay of Pb-210.
Concentrations of Po-210 in aquatic foods are typically similar to, orrather higher than, those of Pb-210.
For fish products, UNSCEAR (2000) gives reference concentrations forPo-210 of 2 Bq/kg.
Dose effects/dosimetry
Po-210 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, Po-210 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerationsP
Environment Agency Radionuclides Handbook138
Name
Radioactivehalf-life
Parent
Plutonium-238
87.7 years
Cm-242
Symbol
Principal decaymode
Daughter
Pu-238
Alpha
U-234 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Formed by neutron activation of uranium in a nuclear reactor, followed by
decay of the activation products
Uses• As a power source for satellites and other space equipment• As a power source for heart pacemakers
ModesLand
• Deposition to soils as a result of weapons testing• Releases from nuclear reactors or experimental facilities
ofAir
• Releases due to weapons testing• Releases from nuclear reactors or experimental facilities
releaseWater • Releases from nuclear reactors or experimental facilities
Speciation
In aqueous solution, plutonium can exhibit any offour oxidation states.
The stable oxidation state(s) in any solution are afunction of environmental conditions such as pHand Eh.
Plutonium reacts slowly with water and rapidlywith dilute acids.
It forms halide and oxide compounds.
Analogue species
There are chemical, biochemical andbiogeochemical similarities between Pu andvarious other actinides, notably Np, Am and Cm.
However, the environmental behaviour of Pu hasbeen studied more extensively than those otheractinides, so there is little merit in using them asanalogues for Pu.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Pu-238 is highly particle reactiveand therefore binds strongly tosoils and sediments.
It is strongly excluded fromplants and is mainly present ontheir surfaces as externalcontamination.
Aquatic
Pu-238 is also highly particlereactive in the aquaticenvironment and thereforetends to bind to suspendedsediments and hence migrate tobottom sediments.
Atmospheric
Pu-238 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. nitrate, might alsoarise.
Environmental sink
Because of its high particlereactivity, Pu-238 will tend toremain in such soil systems untilit decays.
In aquatic systems, bottomsediments are the most likelyenvironmental sink.
Intake and uptake routes
Pu-238 is strongly excluded from plants and is mainly present ontheir surfaces as external contamination.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation.
Uptake from the gastrointestinal tract is limited (<0.1 %), althoughenhanced concentrations of Pu-238 may occur in the liver andskeleton.
Concentrations in marine and freshwater fish are only about a factor30 higher than concentrations in water. However, concentrations inmolluscs, crustaceans and aquatic plants can be a factor of 300 ormore higher than the surrounding water.
Dose effects/dosimetry
Pu-238 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, Pu-238 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerationsP
Environment Agency Radionuclides Handbook140
Name
Radioactivehalf-life
Parent
Plutonium-239
2.4 x 104 years
Np-239
Symbol
Principal decaymode
Daughter
Pu-239
Alpha
U-235 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Formed by neutron activation of uranium in a nuclear reactor, followed by decay
of the activation products
Uses• As the basic fuel for fast breeder reactors• The source of explosive power in nuclear weapons
ModesLand
• Deposition to soils as a result of weapons testing• Releases from nuclear reactors or experimental facilities
ofAir
• Releases due to weapons testing• Releases from nuclear reactors or experimental facilities
releaseWater • Liquid discharges from nuclear facilities
Speciation
In aqueous solution, plutonium can exhibit any offour oxidation states.
The stable oxidation state(s) in any solution are afunction of environmental conditions such as pHand Eh.
Plutonium reacts slowly with water and rapidlywith dilute acids.
It forms halide and oxide compounds.
Analogue species
There are chemical, biochemical andbiogeochemical similarities between Pu andvarious other actinides, notably Np, Am and Cm.
However, the environmental behaviour of Pu hasbeen studied more extensively than those otheractinides, so there is little merit in using them asanalogues for Pu.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Pu-239 is highly particle reactiveand therefore binds strongly tosoils and sediments.
It is strongly excluded fromplants and is mainly present ontheir surfaces as externalcontamination.
Aquatic
Pu-239 is also highly particlereactive in the aquaticenvironment and thereforetends to bind to suspendedsediments and hence migrate tobottom sediments.
Atmospheric
Pu-239 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. nitrate, might alsoarise.
Environmental sink
Because of its high particlereactivity, Pu-239 will tend toremain in such soil systems.
In aquatic systems, bottomsediments are the most likelyenvironmental sink.
Intake and uptake routes
Pu-239 is strongly excluded from plants and is mainly present ontheir surfaces as external contamination.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation.
Uptake from the gastrointestinal tract is limited (<0.1 %), althoughenhanced concentrations of Pu-239 may occur in the liver andskeleton.
Concentrations in marine and freshwater fish are only about a factor30 higher than concentrations in water. However, concentrations inmolluscs, crustaceans and aquatic plants can be a factor of 300 ormore higher than the surrounding water.
Dose effects/dosimetry
Pu-239 is primarily an alpha emitter.
Activity deposited on the outer layers of organisms(e.g. skin) will therefore be of little radiologicalconsequence.
Therefore, Pu-239 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerationsP
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Name
Radioactivehalf-life
Parent
Plutonium-240
6,537 years
Cm-244
Symbol
Principal decaymode
Daughter
Pu-240
Alpha
U-236 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modesChemical properties/characteristics
Production• Formed by neutron activation of uranium in a nuclear reactor, followed by decay
of the activation products
Uses • No significant commercial uses
Modes Land• Deposition to soils as a result of weapons testing• Releases from nuclear reactors or experimental facilities
ofAir
• Releases due to weapons testing• Releases from nuclear reactors or experimental facilities
releaseWater • Releases from nuclear reactors or experimental facilities
Speciation
In aqueous solution, plutonium can exhibit any offour oxidation states.
The stable oxidation state(s) in any solution are afunction of environmental conditions such as pHand Eh.
Plutonium reacts slowly with water and rapidlywith dilute acids.
It forms halide and oxide compounds.
Analogue species
There are chemical, biochemical andbiogeochemical similarities between Pu andvarious other actinides, notably Np, Am and Cm.
However, the environmental behaviour of Pu hasbeen studied more extensively than those otheractinides, so there is little merit in using them asanalogues for Pu.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Pu-240 is highly particle reactiveand therefore binds strongly tosoils and sediments.
It is strongly excluded fromplants and is mainly present ontheir surfaces as externalcontamination.
Aquatic
Pu-240 is also highly particlereactive in the aquaticenvironment and thereforetends to bind to suspendedsediments and hence migrate tobottom sediments.
Atmospheric
Pu-240 would be expected todisperse as an aerosol. The mostlikely chemical form would bean oxide, but other forms, e.g.nitrate, might also arise.
Environmental sink
Because of its high particlereactivity, Pu-240 will tend toremain in such soil systems untilit decays.
In aquatic systems, bottomsediments are the most likelyenvironmental sink.
Intake and uptake routes
Pu-240 is strongly excluded from plants and is mainly present ontheir surfaces as external contamination.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation.
Uptake from the gastrointestinal tract is limited (<0.1 %), althoughenhanced concentrations of Pu-240 may occur in the liver andskeleton.
Concentrations in marine and freshwater fish are only about a factor30 higher than concentrations in water. However, concentrations inmolluscs, crustaceans and aquatic plants can be a factor of 300 ormore higher than the surrounding water.
Dose effects/dosimetry
Pu-240 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, Pu-240 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerationsP
Environment Agency Radionuclides Handbook144
Name
Radioactivehalf-life
Parent
Plutonium-241
14.4 years
Cm-245
Symbol
Principal decaymode
Daughter
Pu-241
Beta
Am-241 [R]
Origin
Grouping
Detection
Breeding
Artificial
Laboratory
Production, uses and modes of release
Decay modesChemical properties/characteristics
Production• Formed by neutron activation of uranium in a nuclear reactor, followed by decay
of the activation products
Uses • No significant commercial uses
Modes Land• Deposition to soils as a result of weapons testing• Releases from nuclear reactors or experimental facilities
ofAir
• Releases due to weapons testing• Releases from nuclear reactors or experimental facilities
releaseWater • Liquid discharges from nuclear facilities
Speciation
In aqueous solution, plutonium can exhibit any offour oxidation states.
The stable oxidation state(s) in any solution are afunction of environmental conditions such as pHand Eh.
Plutonium reacts slowly with water and rapidlywith dilute acids.
It forms halide and oxide compounds.
Analogue species
There are chemical, biochemical andbiogeochemical similarities between Pu andvarious other actinides, notably Np, Am and Cm.
However, the environmental behaviour of Pu hasbeen studied more extensively than those otheractinides, so there is little merit in using them asanalogues for Pu.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Pu-241 is highly particle reactiveand therefore binds strongly tosoils and sediments.
It is strongly excluded fromplants and is mainly present ontheir surfaces as externalcontamination.
Aquatic
Pu-241 is also highly particlereactive in the aquaticenvironment and thereforetends to bind to suspendedsediments and hence migrate tobottom sediments.
Atmospheric
Pu-241 would be expected todisperse as an aerosol.
The most likely chemical formwould be an oxide, but otherforms, e.g. nitrate, might alsoarise.
Environmental sink
Because of its high particlereactivity, Pu-241 will tend toremain in such soil systems untilit decays.
In aquatic systems, bottomsediments are the most likelyenvironmental sink.
Intake and uptake routes
Pu-241 is strongly excluded from plants and is mainly present ontheir surfaces as external contamination.
The main routes of intake by animals will typically be by ingestion ofcontaminated soil or sediment, or by inhalation.
Uptake from the gastrointestinal tract is limited (<0.1 %), althoughenhanced concentrations of Pu-241 may occur in the liver andskeleton.
Concentrations in marine and freshwater fish are only about a factor30 higher than concentrations in water. However, concentrations inmolluscs, crustaceans and aquatic plants can be a factor of 300 ormore higher than the surrounding water.
Dose effects/dosimetry
Pu-241 is primarily an emitter of very low energybeta particles.
Therefore, Pu-241 is of greatest potentialsignificance when internally incorporated.
Internally incorporated Pu-241 may be lessimportant dosimetrically than its decay productAm-241 because of the intense alpha emissions ofthe latter.
Species-specific considerations
No species-specific considerationsP
Environment Agency Radionuclides Handbook146
Name
Radioactivehalf-life
Parent
Radium-226
1,600 years
Th-230
Symbol
Principal decaymode
Daughter
Ra-226
Alpha
Rn-222 [R]
Origin
Grouping
Detection
Radiogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Naturally in all environmental media through the decay of U-238• By product of uranium mining and milling
Uses• In sealed sources for the treatment of cancer• Historically, used as a component of luminous paint and in lightening conductors
Modes Land• Disposed uranium mill tailings• Disposal of luminising waste (past practices)
ofAir
• From burning coal• As part of spent fuel
releaseWater • As part of spent fuel
Speciation
Radium is an alkaline earth element and, as aconsequence, the most important species is theRa2+ ion.
Isotopes of radium can therefore be expected totake part in a number of precipitation andsubstitution reactions.
Precipitation as sulphate, carbonate or hydroxideis possible.
Analogue species
The alkaline earth elements Ca, Sr, Ba and Raexhibit close chemical, biochemical andbiogeochemical analogies.
However, Ra has been studied extensively in itsown right, so it is not necessary to rely onanalogies with the other alkaline earths.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ra-226 is widely dispersed insoils due to the presence of U-238. It mainly decays in situ,as it is incorporated in themineral phase.
Ra-226 is strongly excludedfrom plants.
Aquatic
The Ra-226 content of surfacewaters is low and it has only alimited tendency to bind withsediments.
However, highly insoluble Ba/Rasulphates may be precipitated inthe context of uraniumprocessing.
Atmospheric
Ra-226 is not generally of greatinterest in the context ofatmospheric releases, althoughit could be dispersed fromfacilities where uranium oreshave been processed.
Environmental sink
Most Ra-226 decays local to itspoint of production from decayof primordial U-238.
However, Ra-226 enteringsurface waters may either decayin the water column or betransferred to sediments.
High concentrations of Ra-226may accumulate in tailingsponds at uranium oreprocessing facilities.
Intake and uptake routes
Ra-226 is strongly excluded from plants.
Its fractional gastrointestinal absorption in mammals is typically only~3 %.
Ra-226 entering the systemic circulation is mainly accumulated inmineral bone.
Ra-226 exhibits concentration ratios relative to water of about 50 inboth marine and freshwater fish. It accumulates in the bone, scalesand fins.
Concentration ratios in marine invertebrates range from 3 to 7,000.Typical values are 100 for molluscs and 1,000 for crustaceans.
Dose effects/dosimetry
Ra-226 is primarily an alpha emitter.
Activity deposited on the outer layers of organisms(e.g. skin) will therefore be of little radiologicalconsequence.
Thus, Ra-226 is of greatest potential significancewhen internally incorporated in organs and tissuesthat are susceptible to the effects of alpharadiation.
Ra-226 decays to Rn-222. Although much of thisRn-222 diffuses out of the body, some remainstrapped and decays in situ.
Species-specific considerations
No species-specific considerations
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Name
Radioactivehalf-life
Parent
Rubidium-81
4.6 hours
N/A
Symbol
Principal decaymode
Daughter
Rb-81
EC
Kr-81 [R]
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • By irradiation of stable precursors in a cyclotron or nuclear reactor
Uses • In the production of krypton-81 (the decay product)
Modes Land • Sewage sludge application to land
of Air • Not generally released to air
release Water • Hospital releases to sewers, but would probably decay away before this can occur
Speciation
Rubidium is an alkali metal whose chemicalbehaviour is determined by the properties of theRb+ ion.
Most of the compounds of rubidium are ionic innature, although more complex species can beformed.
Analogue species
Rb has no known biological role, but it is a closechemical analogue for K and can substitute for it,to some degree, in biota.
In terms of binding to soils and sediments, both Kand Cs are useful analogues.
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Rubidium is moderately particlereactive and so a substantialproportion will remain in situ.
A limited amount will betransported around theterrestrial environment insurface and groundwaters.
Aquatic
Freshwater sediments mayabsorb Rb-81 significantly. But islikely to behave conservativelyin the marine environment.
Atmospheric
It is likely to be released as anaerosol, but its very short half-life will limit the amount ofdeposition to plants and groundsurfaces
Environmental sink
Because of its short half-life Rb-81 in the terrestrialenvironment will decay close toits point of deposition.
In aquatic environments, Rb-81will mainly decay in the watercolumn as it disperses, orpossibly in deposited freshwatersediments.
Intake and uptake routes
The very short radioactive half-life of Rb-81 will preclude substantialuptake by plants.
Rb-81 is highly bioavailable to animals and would be efficientlyabsorbed by animals grazing on externally contaminated vegetation.
It would rapidly become relatively uniformly distributed throughoutthe bodies of those animals.
Concentration ratios relative to water are likely to be much higher infreshwater than marine organisms, although the very short half-life ofRb-81 would limit the extent of accumulation.
Dose effects/dosimetry
Rb-81 is a positron emitter. Therefore, there is astrong 0.511 MeV gamma ray emission.
External exposure will therefore be an importantexposure pathway.
Rb-81 taken up by biota would be relativelyuniformly distributed throughout their tissues, soindividual organ and tissue doses would be ofsimilar magnitude to the average whole-bodydose.
Species-specific considerations
As Rb-81 is a chemical analogue for K, which is anessential element for almost all biota, there are nomajor species-specific considerations.
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Environment Agency Radionuclides Handbook150
Name
Radioactivehalf-life
Parent
Rubidium-86
18.7 days
N/A
Symbol
Principal decaymode
Daughter
Rb-86
Beta
Sr-86
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses • In medicine for the determination and treatment of electrolyte disorders
Modes Land • Sewage sludge application to land
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Rubidium is an alkali metal whose chemicalbehaviour is determined by the properties of theRb+ ion.
Most of the compounds of rubidium are ionic innature, although more complex species can beformed.
Analogue species
Rb has no known biological role, but it is a closechemical analogue for K and can substitute for it,to some degree, in biota.
In terms of binding to soils and sediments, both Kand Cs are useful analogues.
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Environment Agency Radionuclides Handbook 151
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Rubidium is moderately particlereactive and so a substantialproportion will remain in situ.
A limited amount will betransported around theterrestrial environment insurface and groundwaters.
Aquatic
Freshwater sediments mayabsorb Rb-86 significantly. But islikely to behave conservativelyin the marine environment.
Atmospheric
Rb-86 is likely to be released asan aerosol and may bedeposited on plants and soils bywet and dry depositionprocesses.
Environmental sink
Because of its short half-life, Rb-86 in the terrestrialenvironment will decay close toits point of deposition.
In aquatic environments, Rb-86will mainly decay in the watercolumn as it disperses, orpossibly in deposited freshwatersediments.
Intake and uptake routes
Significant rapid, metabolically active foliar absorption of Rb-86deposited on plants is likely to occur.
Rb-86 is highly bioavailable to animals and would be efficientlyabsorbed by animals grazing on externally contaminated vegetation.
It would rapidly become relatively uniformly distributed throughoutthe bodies of those animals.
Concentration ratios relative to water are likely to be much higher infreshwater than marine organisms. For freshwater organisms, valuesof a few hundred are typical.
Dose effects/dosimetry
Rb-86 taken up by biota would be relativelyuniformly distributed throughout their tissues, soindividual organ and tissue doses would be ofsimilar magnitude to the average whole-bodydose.
Species-specific considerations
As Rb-86 is a chemical analogue for K, which is anessential element for almost all biota, there are nomajor species-specific considerations.
R
Environment Agency Radionuclides Handbook152
Name
Radioactivehalf-life
Parent
Rhenium-186
3.7 days
N/A
Symbol
Principal decaymode
Daughter
Re-186
Beta
Os-186 [R]
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced by irradiation of stable precursors in a cyclotron or nuclear reactor
Uses• To provide pain relief from bone cancer• In the treatment of rheumatoid arthritis
Modes Land• Sewage sludge application to land, but would probably decay substantially
before this can occurof
Air • Not generally released to airrelease
Water • Hospital releases to sewers
Speciation
Rhenium is a Group VII element that can showoxidation states from -1 through to +7.
It forms compounds with the halogens andoxygen, and can form an extensive range ofcomplexes, of which many contain bonds withoxygen or nitrogen.
Analogue species
Almost nothing is known about the environmentalbehaviour of Re.
Although there are chemical similarities with Tc,both elements have complex, redox-dependentchemistries and it would not be appropriate to relyon Tc as an environmental analogue for Re.
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Environment Agency Radionuclides Handbook 153
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Re-186 is most likely to enterthe terrestrial environment byatmospheric deposition.
It is likely to exhibit only limitedparticle reactivity in oxicconditions.
Aquatic
As for the terrestrialenvironment, Re-186 is likely toexhibit only limited particlereactivity in oxic conditions.
Atmospheric
If Re-186 were released to theatmosphere, it would disperse asan aerosol.
Environmental sink
In the terrestrial environment,Re-186 is likely to decay close toits site of deposition.
In the aquatic environment, it islikely to decay as it disperses inthe water column.
Intake and uptake routes
Foliar uptake of Re-186 could occur, but its short half-life means thatit will mainly be present on the external surfaces of plants.
Re-186 ingested by animals is likely to be highly bioavailable andwidely dispersed throughout soft tissues.
Re-186 may exhibit high concentration ratios relative to water inmarine invertebrates and seaweed.
However, its short half-life may prevent such ratios being achieved.
Dose effects/dosimetry
Re-186 is mainly a beta emitter.
However, a small amount of gamma emission alsooccurs.
Because of its potentially high bioavailability, thepathway of greatest interest may possibly beinternal exposure of animals.
Species-specific considerations
Insufficient information is available to permit anycomment to be made.
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Environment Agency Radionuclides Handbook154
Name
Radioactivehalf-life
Parent
Radon-222
3.8 days
Ra-226
Symbol
Principal decaymode
Daughter
Rn-222
Alpha
Po-218 [R]
Origin
Grouping
Detection
Radiogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • From the decay of radium-226 in the uranium-238 decay chain
Uses • Sometimes used in sealed tubes in the treatment of cancer
Modes Land • Naturally present in soil and rock pores containing uranium
of Air • Emitted from soils and rocks containing uranium
release Water • Naturally present in waters containing radioactive precursors
Speciation
Radon is a noble gas and, as such, forms only alimited number of chemical compounds due to itslack of reactivity.
One such example is RnF2.
Analogue species
There are broad similarities in the behaviour of allthe noble gases (Ne, Ar, Kr, Xe, Rn).
However, Rn-222 is characterised by various short-lived, chemically reactive and radioactive progeny.
As it has been studied extensively in its own right,there is no need to resort to analogies.
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Environment Agency Radionuclides Handbook 155
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Rn-222 is not deposited to asignificant degree in terrestrialenvironments.
Its short-lived descendants dodeposit to surfaces, but this ismainly relevant in mitigatinginhalation exposures (dosesfrom Rn-222 inhalation aredominated by the decay ofshort-lived descendants).
Aquatic
Rn-222 is produced from Ra-226 in aquatic environments,but is of little radiologicalsignificance compared with itslong-lived descendants, Pb-210and Po-210.
Atmospheric
Rn-222 is produced from Ra-226present in soils and sedimentsand is subsequently released tothe atmosphere.
Outdoor concentrations vary byabout a factor of 100,depending on the geographicalcontext and near-surfaceuranium concentrations.
Concentrations are higher inenclosed spaces, e.g. burrows.
Environmental sink
Rn-222 released from soils andsediments decays mainly in theatmosphere.
However, much of the Rn-222produced in soils and sedimentsdecays in situ.
Rn-222 produced at depths ofmore than about 0.3 m haslittle chance of escaping fromthe soil surface.
Intake and uptake routes
The main intake route for Rn-222 and its short-lived progeny isinhalation.
Being a noble gas, very little radon is retained in the body.
However, short-lived descendants can settle and attach themselves tothe lung surface.
Dose effects/dosimetry
Rn-222 and its short-lived progeny emit a mixtureof alpha, beta and gamma radiation.
In animals, short-lived progeny of Rn-222 depositon, and preferentially irradiate, the surfaces of thetrachea and bronchi.
Species-specific considerations
Rn-222 is mainly of interest in respect of terrestrialanimals.
Exposures of burrow-dwelling animals are ofparticular importance.
R
Environment Agency Radionuclides Handbook156
Name
Radioactivehalf-life
Parent
Ruthenium-106
373.6 days
N/A
Symbol
Principal decaymode
Daughter
Ru-106
Beta
Rh-106 [R]
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced as a result of fission processes in a nuclear reactor
Uses • Sometimes used in medical research and diagnostics
ModesLand • Reaches surface soils as a result of sewage sludge applied to land
ofAir • Sometimes released from nuclear reactors, hospitals and research facilities
release Water• Sometimes released from nuclear reactors, hospitals and research facilities• Liquid discharges from nuclear facilities
Speciation
Ruthenium is a platinum metal that showsoxidation states from -2 through to +8; theprincipal ones are +2 and +3.
Ruthenium forms compounds with the halogensand oxygen.
It can also form various complexes, of which thoseinvolving bonding to nitrogen are the most stable.
Analogue species
There are broad similarities in the behaviour of allthe noble gases (Ne, Ar, Kr, Xe, Rn).
However, Rn-222 is characterised by various short-lived, chemically reactive and radioactive progeny.
As it has been studied extensively in its own right,there is no need to resort to analogies.
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Environment Agency Radionuclides Handbook 157
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Ru-106 is moderately adsorbedin mineral soils, but is stronglyadsorbed in organic soils.
In mineral soils, cationic formsadsorb much more stronglythan anionic forms.
Nitrogen-ruthenium complexesare only poorly adsorbed andare available for plant uptake.
Aquatic
Ru-106 is highly particlereactive, although the degree ofsorption to freshwatersediments is much less than tomarine sediments.
In seawater, almost no Ru ispresent in ionic form.Particulate-bound and colloidalRu are dominant.
Atmospheric
If Ru-106 were to be released toatmosphere, it would be as anaerosol.
Environmental sink
Intake and uptake routes
In terrestrial environments, Ru-106 can be expected to decayclose to its site of deposition.
In freshwater environments, itmay be transported as ionic orcolloidal forms.
In the marine environment,decay will occur in the watercolumn or deposited sediments.
Intake and uptake routes
In terrestrial environments, uptake to plants from foliar absorption islikely to be more important than root uptake in the first season afterdeposition.
The fractional gastrointestinal absorption of Ru in mammals is <10 %.
Ru-106 entering the systemic circulation becomes relatively uniformlydistributed and is well retained.
Concentration ratios relative to water are <10 for the soft tissues ofcrustaceans, but ~100 for whole animals. For molluscs, soft tissueand whole body ratios are 500 and 2,000, respectively. In fish, wholebody ratios are typically between 10 to 100.
Dose effects/dosimetry
Ru-106 is a soft beta emitter.
However, it decays to the very short-lived Rh-106,which emits energetic beta particles andmoderately energetic gamma rays.
Internal and external exposures from Ru-106/Rh-106 should be taken into account.
Species-specific considerations
Molluscs and crustaceans accumulate Ru-106 intheir guts and external organs.
Uptake to the shell can be particularly important.
R
Environment Agency Radionuclides Handbook158
Name
Radioactivehalf-life
Parent
Sulphur-35
87.3 days
P-35
Symbol
Principal decaymode
Daughter
S-35
Beta
Cl-35
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• By irradiation of stable isotopes of sulphur and carbon with neutrons in a nuclear
reactor or cyclotron
Uses • Used in research as a radiotracer
ModesLand • Deposition from air onto surface soils
ofAir • Released from gas-cooled nuclear reactors
release Water• Release to sewers• Leaching to groundwater from surface soils
Speciation
Sulphur can exhibit oxidation states of -2, 0, +2,+4 and +6.
It can thus form a wide range of compounds,particularly with the halogens.
Sulphur also has a great tendency towardscatenation (the formation of element-elementbonds).
Analogue species
Sulphur is an essential element for all livingorganisms.
There are extensive studies of its behaviour in theenvironment and it is inappropriate to consider itby analogy with any other element.
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Environment Agency Radionuclides Handbook 159
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
S-35 is likely to enter theterrestrial environment bydeposition from theatmosphere.
S-35 as SO2 is strongly taken upby plants through foliarabsorption and is reduced toorganic sulphur compounds.
The mechanism of depositionand uptake is affected byseasonal factors.
Aquatic
The majority of sulphur inseawater is present as sulphateand little is thought to bepresent as particulates.
Concentrations of sulphur infreshwaters are generally muchlower than those in marinewaters.
Atmospheric
S-35 is likely to be released tothe atmosphere as the gasesCOS or SO2.
However, it could also bereleased as a particulate aerosol,e.g. sulphate.
Environmental sink
S-35 is mainly of interest in theterrestrial environment.
It will mainly be accumulatedby plants and soils and willdecay in situ.
Intake and uptake routes
S-35 will be rapidly and efficiently taken up in plants by foliarabsorption.
It is highly available to animals, gastrointestinal absorption beingvirtually complete.
S-35 entering the systemic circulation from diet is uniformlydistributed in the body and is well retained.
Concentration ratios in aquatic organisms relative to water are ~0.5and 100 for marine and freshwater organisms, respectively.
Dose effects/dosimetry
S-35 is a pure beta emitter and is only of interestin the context of internal irradiation.
As it is relatively uniformly distributed in plantsand animals, doses to individual organs and tissueswill be of similar magnitude to average whole-body doses.
Species-specific considerations
No major species-specific considerations have beenidentified.
S
Environment Agency Radionuclides Handbook160
Name
Radioactivehalf-life
Parent
Antimony-125
2.8 years
N/A
Symbol
Principal decaymode
Daughter
Sb-125
Beta [gamma]
Te-125m [R],Te-125
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses • No significant uses outside research activities
Modes Land • During treatment and disposal of spent fuel
of Air • During treatment and disposal of spent fuel
release Water • Not generally released to water
Speciation
Antimony is a metalloid of Group V, whosechemistry is dominated by the +3 and +5oxidation states.
Antimony forms compounds with hydrogen,oxygen, sulphur, halides and other elements.
It can form antimonyl compounds involvingantimony and oxygen (SbO)+.
Analogue species
Sb exhibits some chemical and biochemicalsimilarities to arsenic.
However, there are also considerable differencesand the environmental behaviour of Sb is besttreated without reference to potential analogues.
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Environment Agency Radionuclides Handbook 161
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
In general, when Sb-125 isadded to soils in soluble form, itcan be expected to remainmobile as it is, at most,moderately particle reactive.
Sb-125 is not very available toplants.
Aquatic
Sb-125 is likely to be present inboth fresh and marine watersmainly in ionic form.
However, a substantial fractionmay become bound tosuspended and bottomsediments.
Atmospheric
If Sb-125 were released to theatmosphere, it would probablybe as an aerosol rather than thehighly toxic gas stibine (SbH3).
Environmental sink
In the terrestrial environment,some migration of Sb-125 inthe soil profile can be expectedbefore it decays.
In aquatic environments, decaywill occur mainly in the watercolumn and only to a limiteddegree in deposited sediments.
Intake and uptake routes
Sb-125 is not very available to plants and there is no evidence ofsubstantial foliar uptake.
The fractional gastrointestinal absorption in mammals is typically ~1 %.
Antimony is widely distributed in the soft tissues of mammals, butbone is the main long-term reservoir.
Concentration ratios of Sb-125 in aquatic organisms relative to waterare typically in the range 5 to 100.
Dose effects/dosimetry
Sb-125 is a mixed beta-gamma emitter.
Gamma emissions are of high yield and moderateenergy.
Because of the low bioavailability of Sb-125,external irradiation may be more important thaninternal irradiation in terrestrial environments.
Species-specific considerations
No major species-specific considerations have beenidentified.
S
Environment Agency Radionuclides Handbook162
Name
Radioactivehalf-life
Parent
Selenium-75
120 days
N/A
Symbol
Principal decaymode
Daughter
Se-75
EC
As-75
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Neutron activation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses• In medicine for diagnostic imaging• To investigate the production of digestive enzymes
ModesLand • Sewage sludge application to land
of Air• Not generally released to air, but some releases of volatile selenium compounds
may occur from sewage sludgerelease
Water • Hospital releases to sewers
Speciation
Selenium can exist in one of four oxidation states:-2 (selenide compounds), 0 (elemental selenium),+4 (selenite compounds) and +6 (selenatecompounds).
Selenide and elemental selenium are expected tobe present in reducing conditions, with seleniteand selenate species appearing as conditions movetowards oxidising.
Analogue species
There are considerable similarities between thechemistry and biochemistry of Se and S, and Secan substitute for S in a number of contexts.
However, Se is an essential trace element in itsown right, so this analogy should be usedcautiously.
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Environment Agency Radionuclides Handbook 163
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
The chemistry of Se in soils iscomplex, but it can bindstrongly to clay minerals. Theproportion of available Se insoils can vary from <1 % to 30 %.
There are strong distinctionsbetween normal and Se-deficient soils.
Selenate is likely to be muchmore available than selenite.
Aquatic
Se-75 in aquatic systems ismoderately particle reactive.
Binding to sediments dependson the acidity and the Fe, Mnand clay contents of thesediments.
Atmospheric
Se-75 could be released toatmosphere either as an aerosolor as a gas, e.g. dimethylselenide.
Environmental sink
Se-75 deposited in theterrestrial environment is likelyto be strongly retained in theplant-soil system and decayclose to its point of deposition.
In aquatic systems, it may decayeither in the water column or inbottom sediments, dependingon the chemical form.
Intake and uptake routes
Se-75 is very highly bioavailable to both terrestrial plants and animals(especially as selenate) and is likely to be substantially accumulated,particularly in Se-deficient conditions.
Both foliar uptake and root absorption are likely to be important inplants.
Se is widely distributed in animal tissues and is well retained.
Concentration ratios relative to water are ~100 for most aquaticorganisms.
Dose effects/dosimetry
Se-75 is predominantly a gamma-emittingradionuclide.
However, because of its high bioavailability andrelatively long half-life, internal irradiation is likelyto be more important than external irradiation,especially for small organisms.
Species-specific considerations
No major species-specific considerations have beenidentified.
However, Se-deficient terrestrial environments arelikely to be associated with an exceptionally highdegree of bioavailability of Se-75.
S
Environment Agency Radionuclides Handbook164
Name
Radioactivehalf-life
Parent
Samarium-153
46.7 hours
N/A
Symbol
Principal decaymode
Daughter
Sm-153
Beta
Eu-153
Origin
Grouping
Detection
Activation
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Produced during fission in a nuclear reactor• By irradiating stable precursors in a cyclotron
Uses• In medicine for relieving pain from secondary bone cancers• For diagnostic imaging and radioimmunotherapy
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Samarium is a rare earth element that showsoxidation states of +2 and +3, and whosecompounds are typical of other rare earthcompounds.
As such, samarium forms compounds withhydrogen, oxygen and the halides. It also formsstable complexes.
Analogue species
There are considerable similarities in the chemistry,biochemistry and biogeochemistry of all thelanthanide elements.
In particular, Ce and Eu are moderately extensivelystudied elements that are analogous to Sm.
S
Environment Agency Radionuclides Handbook 165
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Sm-153 is highly particlereactive, and hence wouldremain bound to soil particlesand on the surfaces of plants.
Transfers from plant to soil andbulk movement of soils wouldbe the main transportmechanisms.
Aquatic
Sm-153 is highly particlereactive in the aquaticenvironment.
It is likely to bind to suspendedsediments close to its point ofdischarge, and deposit from thewater column to bottomsediments.
Atmospheric
If Sm-153 was released to theatmosphere, it would be as anaerosol and probably in oxideform.
Environmental sink
The short half-life and highparticle reactivity of Sm-153mean that it is likely to decayclose to its site of deposition interrestrial environments.
In aquatic environments,bottom sediments close to thesource of release may form animportant sink.
Intake and uptake routes
Intake by terrestrial animals is likely to be mainly the ingestion of Sm-153 present on the exterior surfaces of plants or deposited on soil.
Sm-153 is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically <0.1 %.
Any Sm-153 that is absorbed is mainly deposited in the liver andskeleton.
In the aquatic environment, uptake by fish and invertebrates ismainly direct from the water rather than food. Uptake by aquaticplants is likely to be by surface adsorption.
Dose effects/dosimetry
Sm-153 is mainly an emitter of low-energy betaparticles.
External deposits of Sm-153 on plants and animalswill mainly result in irradiation of superficial outertissues, which are often insensitive to radiationexposure.
Internal exposure will be limited by the lowbioavailability of Sm-153.
Species-specific considerations
The high uptakes in molluscs, crustaceans andaquatic plants could be important.
S
Environment Agency Radionuclides Handbook166
Name
Radioactivehalf-life
Parent
Strontium-89
50.5 days
N/A
Symbol
Principal decaymode
Daughter
Sr-89
Beta
Y-89
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Produced as a fission product in a nuclear reactor• In a cyclotron for medical purposes
Uses • Used in medicine to treat metastases in bone cancer
Modes Land • Sewage sludge application to land
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Strontium is an alkaline earth element and thusthe most important species is the Sr2+ ion.
Isotopes of strontium can therefore be expected totake part in a number of precipitation andsubstitution reactions.
Precipitation as sulphate, carbonate or hydroxideis possible.
Analogue species
The alkaline earths Ca, Sr, Ba and Ra exhibitconsiderable chemical, biochemical andbiogeochemical similarities.
Ratios of Sr-90 to stable Ca have often been usedto characterise the environmental behaviour of theradionuclide.
S
Environment Agency Radionuclides Handbook 167
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Sr-89 is only weakly tomoderately particle reactive insoils.
However, its degree of mobilityis limited by its short half-life.
Foliar uptake of Sr-89 uptakecan be significant.
Aquatic
Sr-89 has only a limitedtendency to bind to sedimentsin either freshwater or marinesystems.
Atmospheric
Sr-89 would be expected todisperse as an aerosol.
Environmental sink
Although Sr-89 is relativelymobile, its short half-life meansit will largely decay in situ interrestrial environments.
However, in freshwater andmarine environments, it may bewidely dispersed beforedecaying, largely in the watercolumn.
Intake and uptake routes
Sr-89 is moderately bioavailable to plants. Foliar uptake can besignificant.
Strontium is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~20 %.
There is considerable early retention in soft tissues. However, thelong-term reservoir for accumulation is bone.
It is only very weakly accumulated by aquatic organisms, typicallyexhibiting concentration ratios relative to water in the range 1 to 5.
Dose effects/dosimetry
Sr-89 is almost a pure beta emitter.
Therefore, externally deposited Sr-89 onlyirradiates superficial tissues, which are not alwaysvery radiosensitive.
However, the radionuclide is relatively highlybioavailable, so internal irradiation is likely to bethe dominant consideration in animals.
In plants, either external or internal irradiationmay be more important, depending on themorphology and physiology of the plant, and thecharacteristics of the deposit.
Species-specific considerations
Accumulation in terrestrial animals seems likely tobe of greater interest than uptake in terrestrialplants or aquatic organisms.
S
Environment Agency Radionuclides Handbook168
Name
Radioactivehalf-life
Parent
Strontium-90
29.1 years
N/A
Symbol
Principal decaymode
Daughter
Sr-90
Beta
Y-90 [R]
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • As a result of fission processes in a nuclear reactor
Uses • As an energy source for powering remote machinery e.g. satellites• In medicine for the treatment of cancer
Modes Land • Deposition onto soils from weapons testing or nuclear accidents
of Air • As a result of a nuclear accident or historic weapons testing
release Water • Liquid discharges from nuclear facilities
Speciation
Strontium is an alkaline earth element and thusthe most important species is the Sr2+ ion.
Isotopes of strontium can therefore be expected totake part in a number of precipitation andsubstitution reactions.
Precipitation as sulphate, carbonate or hydroxideis possible.
Analogue species
The alkaline earths Ca, Sr, Ba and Ra exhibitconsiderable chemical, biochemical andbiogeochemical similarities.
Ratios of Sr-90 to stable Ca have often been usedto characterise the environmental behaviour of theradionuclide.
S
Environment Agency Radionuclides Handbook 169
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Sr-90 is only weakly tomoderately particle reactive insoils.
Foliar uptake of Sr-90 uptakecan be significant, but theradionuclide tends to remain inthe plant part where it wasdeposited and does not becomewidely translocated.
Aquatic
Sr-90 has only a limitedtendency to bind to sedimentsin either freshwater or marinesystems.
Atmospheric
Sr-90 would be expected todisperse as an aerosol.
Environmental sink
Although Sr-90 is relativelymobile, it can often remain insoils and sediments close to itspoint of deposition until itdecays.
However, in freshwater andmarine environments, it may bewidely dispersed beforedecaying in the water columnand bottom sediments.
Intake and uptake routes
Sr-90 is moderately bioavailable to plants.
Strontium is moderately bioavailable to animals, with a fractionalgastrointestinal absorption of ~20 %.
There is considerable early retention in soft tissues. However, thelong-term reservoir for accumulation is bone.
It is only very weakly accumulated by aquatic organisms, typicallyexhibiting concentration ratios relative to water in the range 1 to 5.
Dose effects/dosimetry
Sr-90 and its short-lived daughter Y-90 are almostpure beta emitters.
However, the beta particles from Y-90 areparticularly energetic, so more penetration ofsuperficial tissues from external deposits occursthan with most beta emitters.
However, Sr-90 is relatively highly bioavailable andlong-lived, so internal irradiation is likely to be thedominant consideration in both plants andanimals.
Species-specific considerations
Accumulation in terrestrial animals seems likely tobe of greater interest than uptake in terrestrialplants or aquatic organisms.
S
Environment Agency Radionuclides Handbook170
Name
Radioactivehalf-life
Parent
Technetium-99
2.1 x 105 years
Mo-99, Tc-99m
Symbol
Principal decaymode
Daughter
Tc-99
Beta
Ru-99
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • As a result of fission processes in a nuclear reactor
Uses • Sometimes used to reduce corrosion of steels
Modes Land • Present in soils due to fallout from weapons testing
of Air • Discharged to air from operating nuclear reactors
release Water • Liquid discharges from nuclear facilities
Speciation
Technetium can exist in a number of oxidationstates, although +7 and +4 are the most stableforms in solution.
In oxidising conditions, the pertechnetate ion(TcO4
-) is the most stable form. It gives rise to saltsthat are stable in the pH range 0 to 14, and whichare generally very soluble.
In reducing conditions, oxides of technetium arethe dominant form of the element.
Analogue species
Technetium exhibits complex chemical,biochemical and biogeochemical interactions.
It is, therefore, strongly recommended thatanalogies be used only with extreme caution whenattempting to characterise the environmentalbehaviour of technetium.
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Environment Agency Radionuclides Handbook 171
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Tc-99 could be stronglyaccumulated in stronglyreducing soils and sediments.
In oxic conditions, however, it islikely to be present as thepertechnetate and to be highlymobile.
Aquatic
Tc-99 reacts only weakly withparticulate matter in oxidisingconditions, but can be highlyparticle reactive in reducingconditions.
Discharges to freshwater,estuarine or marineenvironments would beexpected to disperse widely,mixing throughout the worldísoceans in the long term.
Atmospheric
Sr-90 would be expected todisperse as an aerosol.
Environmental sink
Because of its redox-sensitivecharacteristics, highly reducedsoils and sediments can be asink for Tc-99.
However, if the Tc remains inoxic form, it is likely to behighly mobile.
In the marine environment, itwill largely remain present inthe water column until itdecays.
Intake and uptake routes
In oxic conditions, Tc-99 is highly available to plants andconsiderable accumulation can occur.
Tc can be highly available to animals, with fractional gastrointestinalvalues approaching 100 %.
Tc entering the systemic circulation is widely distributed throughoutsoft tissues, but is not well retained.
Concentration ratios relative to water for Tc are about 30 forfreshwater and marine fish, but are about 1,000 for molluscs,crustaceans and seaweed.
Dose effects/dosimetry
Tc-99 is a soft beta emitter.
Therefore, external irradiation is not aconsideration.
As Tc-99 distributes relatively uniformlythroughout body tissues, doses to individualorgans and tissues will be of the same order ofmagnitude as average whole-body doses.
Species-specific considerations
The high concentration ratios exhibited bymolluscs, crustaceans and seaweed mean thatthese species should be given specialconsideration.
Lettuce and spinach have also been observed toexhibit particularly high concentration ratios.
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Environment Agency Radionuclides Handbook172
Name
Radioactivehalf-life
Parent
Technetium-99m
6.02 hours
Mo-99
Symbol
Principal decaymode
Daughter
Tc-99m
IT
Tc-99 [R]
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Irradiation of molybdenum with neutrons in a nuclear reactor or cyclotron
Uses• In medicine for diagnostic purposes• Assessing the results of surgery and medical treatment
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Technetium can exist in a number of oxidationstates, although +7 and +4 are the most stableforms in solution.
In oxidising conditions, the pertechnetate ion(TcO4
-) is the most stable form. It gives rise to saltsthat are stable in the pH range 0 to 14, and whichare generally very soluble.
In reducing conditions, oxides of technetium arethe dominant form of the element.
Analogue species
Technetium exhibits complex chemical,biochemical and biogeochemical interactions.
It is, therefore, strongly recommended thatanalogies be used only with extreme caution whenattempting to characterise the environmentalbehaviour of technetium.
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Environment Agency Radionuclides Handbook 173
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Tc-99m could be stronglyaccumulated in stronglyreducing soils and sediments.
In oxic conditions, however, it islikely to be present as thepertechnetate and to be highlymobile.
In oxic conditions, Tc-99 ishighly available to plants
Aquatic
Tc-99m reacts only weakly withparticulate matter in oxidisingconditions, but can be highlyparticle reactive in reducingconditions.
Discharges to freshwater,estuarine or marineenvironments would beexpected to disperse widely.
Atmospheric
If Tc-99m were released to theatmosphere, it would be as anaerosol.
Environmental sink
The very short half-life meansthat Tc-99m will decay in situ inthe terrestrial environment.
In aquatic environments, it maydisperse a few kilometres beforedecaying in the water column.
Intake and uptake routes
The very short half-life of Tc-99m means that it will have littleopportunity to be transferred to terrestrial animals or aquaticorganisms.
However, following a release to air, Tc-99m would be present on thesurfaces of plants and could be subject to some foliar absorption.
Dose effects/dosimetry
Tc-99m is mainly a gamma emitter.
Therefore, external exposure following depositionin a terrestrial environment may be of greatersignificance than internal exposure, given thelimited time for plant or animal uptake.
Species-specific considerations
The high concentration ratios exhibited bymolluscs, crustaceans and seaweed mean thatthese species should be given specialconsideration.
Lettuce and spinach have also been observed toexhibit particularly high concentration ratios.
T
Environment Agency Radionuclides Handbook174
Name
Radioactivehalf-life
Parent
Thorium-227
18.7 days
Ac-227
Symbol
Principal decaymode
Daughter
Th-227
Alpha
Ra-223 [R]
Origin
Grouping
Detection
Radiogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • From the decay of Ac-227, arising from the decay of U-235
Uses • No specific uses for Th-227
Modes Land• From the decay of naturally occurring U-235 in soils and rocks• Reprocessing of spent fuel
ofAir
• Treatment, reprocessing and disposal of spent fuel• From burning coal
releaseWater • Treatment and disposal of spent fuel
Speciation
The chemistry of thorium is determinedpredominantly by the properties of the +4oxidation state.
Thorium salts tend to hydrolyse in water.
Thorium forms oxide, chloride, nitrate andsulphate compounds, and can also participate inthe formation of organic complexes.
Analogue species
There are similarities between the chemical,biochemical and biogeochemical properties of Thand those of Pu.
However, a considerable amount is known aboutthe environmental behaviour of Th, so it is bestconsidered in its own right.
T
Environment Agency Radionuclides Handbook 175
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Thorium is very highly particlereactive in terrestrialenvironments and is stronglyadsorbed to all soil types.
It is very strongly excluded fromplants.
Aquatic
Thorium is very highly particlereactive in aquatic environmentsand may tend to adsorb tosuspended sediments.
It would migrate to bottomsediments by deposition.
Atmospheric
If Th-227 were released to theatmosphere, it would be as anaerosol.
Environmental sink
Th-227 will decay close to itssite of production in terrestrialenvironments.
In aquatic environments, it willeither decay in the watercolumn or in depositedsediments.
Intake and uptake routes
Thorium is very strongly excluded from plants.
The main route of intake by animals is likely to be ingestion of soil orsediment.
Thorium is also of very limited bioavailability in animals. Thefractional gastrointestinal absorption is typically <0.1 %.
The Th-227 that does enter the systemic circulation is mainlydeposited in bone, with the liver and kidneys as secondary sites ofdeposition.
It is relatively highly accumulated in aquatic organisms. Thesetypically exhibit concentration ratios relative to water of around1,000 in both freshwater and marine environments.
Dose effects/dosimetry
Th-227 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, Th-227 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerations
T
Environment Agency Radionuclides Handbook176
Name
Radioactivehalf-life
Parent
Thorium-228
1.9 years
Ac-228
Symbol
Principal decaymode
Daughter
Th-228
Alpha
Ra-224 [R]
Origin
Grouping
Detection
Radiogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • From the decay of Ac-228 arising from naturally occurring Th-232
Uses • No specific uses for Th-228
ModesLand • From the decay of naturally occurring Th-232 in soils and rocks
of Air• Treatment and disposal of spent fuel• From burning coal
releaseWater • Treatment and disposal of spent fuel
Speciation
The chemistry of thorium is determinedpredominantly by the properties of the +4oxidation state.
Thorium salts tend to hydrolyse in water.
Thorium forms oxide, chloride, nitrate andsulphate compounds, and can also participate inthe formation of organic complexes.
Analogue species
There are similarities between the chemical,biochemical and biogeochemical properties of Thand those of Pu.
However, a considerable amount is known aboutthe environmental behaviour of Th, so it is bestconsidered in its own right.
T
Environment Agency Radionuclides Handbook 177
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Thorium is very highly particlereactive in terrestrialenvironments and is stronglyadsorbed to all soil types.
It is very strongly excluded fromplants.
Aquatic
Thorium is very highly particlereactive in aquatic environmentsand would tend to adsorb tosuspended sediments.
It would migrate to bottomsediments by deposition.
Atmospheric
If Th-228 were released to theatmosphere, it would be as anaerosol.
Environmental sink
Th-228 will decay close to itssite of production in terrestrialenvironments.
In aquatic environments, it willeither decay in the watercolumn or in depositedsediments.
Intake and uptake routes
Thorium is very strongly excluded from plants.
The main route of intake by animals is likely to be ingestion of soil orsediment.
Thorium is also of very limited bioavailability in animals. Thefractional gastrointestinal absorption is typically <0.1 %.
The Th-228 that does enter the systemic circulation is mainlydeposited in bone, with the liver and kidneys as secondary sites ofdeposition.
It is relatively highly accumulated in aquatic organisms. Thesetypically exhibit concentration ratios relative to water of around1,000 in both freshwater and marine environments.
Dose effects/dosimetry
Th-228 is primarily an alpha emitter.
Activity deposited on the outer layers of organisms(e.g. skin) will therefore be of little radiologicalconsequence.
Therefore, Th-228 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerations
T
Environment Agency Radionuclides Handbook178
Name
Radioactivehalf-life
Parent
Thorium-230
7.7 x 104 years
U-234
Symbol
Principal decaymode
Daughter
Th-230
Alpha
Ra-226 [R]
Origin
Grouping
Detection
Radiogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • From the decay of U-234 in nature and in nuclear reactors
Uses • No specific uses for Th-230
ModesLand • From the decay of U-234 in soils and rocks
of Air• Treatment and disposal of spent fuel• From burning coal
releaseWater • Treatment and disposal of spent fuel
Speciation
The chemistry of thorium is determinedpredominantly by the properties of the +4oxidation state.
Thorium salts tend to hydrolyse in water.
Thorium forms oxide, chloride, nitrate andsulphate compounds, and can also participate inthe formation of organic complexes.
Analogue species
There are similarities between the chemical,biochemical and biogeochemical properties of Thand those of Pu.
However, a considerable amount is known aboutthe environmental behaviour of Th, so it is bestconsidered in its own right.
T
Environment Agency Radionuclides Handbook 179
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Thorium is very highly particlereactive in terrestrialenvironments and is stronglyadsorbed to all soil types.
It is very strongly excluded fromplants.
Aquatic
Thorium is very highly particlereactive in aquatic environmentsand would tend to adsorb tosuspended sediments.
It would migrate to bottomsediments by deposition.
Atmospheric
If Th-230 were released to theatmosphere, it would be as anaerosol.
Environmental sink
The distribution of Th-230 inthe environment will usually besimilar to that of uranium.
However, when Th-230 isproduced from U-234 insolution, e.g. in groundwaters,it will be preferentially lost tosolids by adsorption.
Th-230 originating in, oradsorbed to, solids willgenerally decay in situ.
Intake and uptake routes
Thorium is very strongly excluded from plants.
The main route of intake by animals is likely to be ingestion of soil orsediment.
Thorium is also of very limited bioavailability in animals. Thefractional gastrointestinal absorption is typically <0.1 %.
The Th-230 that does enter the systemic circulation is mainlydeposited in bone, with the liver and kidneys as secondary sites ofdeposition.
It is relatively highly accumulated in aquatic organisms. Thesetypically exhibit concentration ratios relative to water of around1,000 in both freshwater and marine environments.
Dose effects/dosimetry
Th-230 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, Th-230 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerations
T
Environment Agency Radionuclides Handbook180
Name
Radioactivehalf-life
Parent
Thorium-231
25.5 hours
U-235
Symbol
Principal decaymode
Daughter
Th-231
Beta
Pa-231 [R]
Origin
Grouping
Detection
Radiogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • From the decay of U-235
Uses • No specific uses for Th-231
ModesLand • From the decay of U-235 in soils and rocks
of Air• Treatment and disposal of spent fuel• From burning coal
releaseWater • Treatment and disposal of spent fuel
Speciation
The chemistry of thorium is determinedpredominantly by the properties of the +4oxidation state.
Thorium salts tend to hydrolyse in water.
Thorium forms oxide, chloride, nitrate andsulphate compounds, and can also participate inthe formation of organic complexes.
Analogue species
There are similarities between the chemical,biochemical and biogeochemical properties of Thand those of Pu.
However, a considerable amount is known aboutthe environmental behaviour of Th, so it is bestconsidered in its own right.
T
Environment Agency Radionuclides Handbook 181
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Thorium is very highly particlereactive in terrestrialenvironments and is stronglyadsorbed to all soil types.
It is very strongly excluded fromplants.
Aquatic
Thorium is very highly particlereactive in aquatic environmentsand would tend to adsorb tosuspended sediments.
It would migrate to bottomsediments by deposition.
Atmospheric
If Th-231 were released to theatmosphere, it would be as anaerosol.
Environmental sink
Th-231 will decay close to itssite of production in terrestrialenvironments.
In aquatic environments, it willeither decay in the watercolumn or in depositedsediments.
Intake and uptake routes
Thorium is very strongly excluded from plants.
The main route of intake by animals is likely to be ingestion of soil orsediment.
Thorium is also of very limited bioavailability in animals. Thefractional gastrointestinal absorption is typically <0.1 %.
The Th-231 that does enter the systemic circulation is mainlydeposited in bone, with the liver and kidneys as secondary sites ofdeposition.
It is relatively highly accumulated in aquatic organisms. Thesetypically exhibit concentration ratios relative to water of around1,000 in both freshwater and marine environments.
Dose effects/dosimetry
As a short-lived radionuclide emitting primarilylow energy beta particles and gamma rays, Th-231is of little environmental significance in its ownright.
It is mainly of interest as the immediate parent ofPa-231.
Species-specific considerations
No major species-specific considerations have beenidentified.
T
Environment Agency Radionuclides Handbook182
Name
Radioactivehalf-life
Parent
Thorium-232
1.41 x 1010 yrs
U-236
Symbol
Principal decaymode
Daughter
Th-232
Alpha
Th-228 [R]
Origin
Grouping
Detection
Primordial
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Naturally during the formation of the Universe• From the decay of U-236
Uses• Manufacture of gas mantles (Thorium oxide)• As a basis for production of fissionable U-233
ModesLand • From naturally occurring Th-232 in soils and rocks
of Air• Treatment and disposal of spent fuel• From burning coal
releaseWater • Treatment and disposal of spent fuel
Speciation
The chemistry of thorium is determinedpredominantly by the properties of the +4oxidation state.
Thorium salts tend to hydrolyse in water.
Thorium forms oxide, chloride, nitrate andsulphate compounds, and can also participate inthe formation of organic complexes.
Analogue species
There are similarities between the chemical,biochemical and biogeochemical properties of Thand those of Pu.
However, a considerable amount is known aboutthe environmental behaviour of Th, so it is bestconsidered in its own right.
T
Environment Agency Radionuclides Handbook 183
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Thorium is very highly particlereactive in terrestrialenvironments and is stronglyadsorbed to all soil types.
It is very strongly excluded fromplants.
Aquatic
Thorium is very highly particlereactive in aquatic environmentsand would tend to adsorb tosuspended sediments.
It would migrate to bottomsediments by deposition.
Atmospheric
If Th-232 were released to theatmosphere, it would be as anaerosol.
Environmental sink
Th-232 is widely distributed inthe environment.
However, it is largelyincorporated in minerals andtends to be very immobile.
Intake and uptake routes
Thorium is very strongly excluded from plants.
The main route of intake by animals is likely to be ingestion of soil orsediment.
Thorium is also of very limited bioavailability in animals. Thefractional gastrointestinal absorption is typically <0.1 %.
The Th-232 that does enter the systemic circulation is mainlydeposited in bone, with the liver and kidneys as secondary sites ofdeposition.
It is relatively highly accumulated in aquatic organisms. Thesetypically exhibit concentration ratios relative to water of around1,000 in both freshwater and marine environments.
Dose effects/dosimetry
Th-232 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, Th-232 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Species-specific considerations
No species-specific considerations
T
Environment Agency Radionuclides Handbook184
Name
Radioactivehalf-life
Parent
Thorium-234
24.1 days
U-238
Symbol
Principal decaymode
Daughter
Th-234
Beta
Pa-234m [R]
Origin
Grouping
Detection
Radiogenic
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • From the decay of U-238
Uses • No specific uses for Th-234
Modes Land• Disposed uranium mill tailings and debris• From naturally occurring U-238 in soil and rocks
ofAir
• Treatment and disposal of spent fuel• From burning coal
releaseWater • Treatment and disposal of spent fuel
Speciation
The chemistry of thorium is determinedpredominantly by the properties of the +4oxidation state.
Thorium salts tend to hydrolyse in water.
Thorium forms oxide, chloride, nitrate andsulphate compounds, and can also participate inthe formation of organic complexes.
Analogue species
There are similarities between the chemical,biochemical and biogeochemical properties of Thand those of Pu.
However, a considerable amount is known aboutthe environmental behaviour of Th, so it is bestconsidered in its own right.
T
Environment Agency Radionuclides Handbook 185
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Thorium is very highly particlereactive in terrestrialenvironments and is stronglyadsorbed to all soil types.
It is very strongly excluded fromplants.
Aquatic
Thorium is very highly particlereactive in aquatic environmentsand would tend to adsorb tosuspended sediments.
It would migrate to bottomsediments by deposition.
Atmospheric
If Th-234 were released to theatmosphere, it would be as anaerosol.
Environmental sink
The distribution of Th-234 inthe environment will usually besimilar to that of U-238.
However, when Th-230 isproduced from U-234 insolution, e.g. in groundwaters,it will be preferentially lost tosolids by adsorption.
Th-234 originating in, oradsorbed to, solids willgenerally decay in situ.
Intake and uptake routes
Thorium is very strongly excluded from plants.
The main route of intake by animals is likely to be ingestion of soil orsediment.
Thorium is also of very limited bioavailability in animals. Thefractional gastrointestinal absorption is typically <0.1 %.
The Th-234 that does enter the systemic circulation is mainlydeposited in bone, with the liver and kidneys as secondary sites ofdeposition.
It is relatively highly accumulated in aquatic organisms. Thesetypically exhibit concentration ratios relative to water of around1,000 in both freshwater and marine environments.
Dose effects/dosimetry
Th-234 is a short-lived beta-gamma emitter.
It is of little dosimetric significance compared withits progeny, notably U-234.
Species-specific considerations
No major species-specific considerations have beenidentified.
T
Environment Agency Radionuclides Handbook186
Name
Radioactivehalf-life
Parent
Thallium-201
3.04 days
N/A
Symbol
Principal decaymode
Daughter
Tl-201
EC
Hg-201
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses • Sometimes used in medical research and diagnostics
Modes Land• Sewage sludge application to land, but would probably decay substantially
before this can occurof
Air • Not generally released to airrelease
Water • Hospital releases to sewers
Speciation
Thallium is a Group III element whose dominantoxidation states are +1 and +3.
Both states can form oxides, nitrates, sulphatesand halides.
The +3 oxidation state can readily formcomplexes.
Analogue species
Biochemically, Tl mimics K, which it resembles insize and ionic charge.
In mammals, it is an insidious poison because itaffects K-activated enzymes in the brain, musclesand skin.
T
Environment Agency Radionuclides Handbook 187
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Tl-201 is likely to bind stronglyto the clay fraction of soils.However, because of its shorthalf-life, it is likely to be mainlyof interest in terms of foliardeposition.
Aquatic
By analogy with K, Tl-201would be expected to be readilyavailable to aquatic organisms.
Atmospheric
If Tl-201 were released toatmosphere, it would be as anaerosol.
Environmental sink
Tl-201 in the terrestrialenvironment is likely to decay insitu.
Dispersion in aquaticenvironments will be limited byits short half-life and it willdecay mainly in the watercolumn
Intake and uptake routes
Some uptake of foliar-deposited Tl-201 may occur, but this has notbeen measured.
Tl-201 is highly bioavailable to animals.
It is completely absorbed from the gastrointestinal tract in mammalsand becomes relatively uniformly distributed throughout the body.
It is likely to be concentrated in the muscle of freshwater fish.
Dose effects/dosimetry
Tl-201 is primarily a gamma-emitting radionuclide.
Because of its short half-life, external irradiation interrestrial environments may be more importantthan internal irradiation.
Species-specific considerations
No major species-specific considerations have beenidentified.
T
Environment Agency Radionuclides Handbook188
Name
Radioactivehalf-life
Parent
Total alpha
Various
Various
Symbol
Principal decaymode
Daughter
Total alpha
Various
Various
Origin
Grouping
Detection
Various
Various
Various
Production, uses and modes of release
Chemical properties/characteristics
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Production• Neutron irradiation of uranium and plutonium (post-actinides)• Decay of post-actinides or naturally occurring isotopes
Uses • Various
Modes Land • Various, e.g. treatment of spent fuel
of Air • Various, e.g. treatment of spent fuel
release Water • Various, e.g. treatment of spent fuel
Speciation
The compounds formed by the different types ofalpha emitter will depend on the species underconsideration. More information can be foundunder the individual radionuclide entries.
Analogue species
Alpha emitters arise mainly in the actinide series,so they exhibit a number of chemical similarities toeach other. However, the range of elements(including Po, Rn, Ra, Th, U, Np, Pu, Am and Cm)is too wide for any general statement to be madeconcerning analogues.
The behaviour of alpha emitters in the environment is most appropriately discussed in the context ofindividual radioisotopes of Po, Rn, Ra, Th, U, Np, Pu, Am and Cm.
Environmental sink
As above
Intake and uptake routes
As above. Also, most alpha emitters exhibit low bioavailability in bothterrestrial plants and animals. However, alpha emitters oftenaccumulate strongly in marine invertebrates and seaweed.
Dose effects/dosimetry
Species-specific considerations
Unless alpha emitters also emit substantialamounts of gamma radiation, which is unusual,they are almost exclusively of relevance in thecontext of internal irradiation.
Species-specific considerations
As above
T
Terrestrial Aquatic Atmospheric
Environment Agency Radionuclides Handbook 189
Name
Radioactivehalf-life
Parent
Total beta
Various
Various
Symbol
Principal decaymode
Daughter
Total beta
Various
Various
Origin
Grouping
Detection
Various
Various
Various
Production, uses and modes of release
Chemical properties/characteristics
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Production • Various, e.g. activation and fission
Uses • Various, including medical and engineering applications
Modes Land • Various
of Air • Various
release Water • Various
Speciation
The compounds formed by the different types ofbeta emitter will depend on the species underconsideration. More information can be foundunder the individual radionuclide entries.
Analogue species
Beta emitters comprise radioisotopes of elementswith a very wide range of chemical, biochemicaland geochemical characteristics. Therefore, nogeneralisations can be made.
Environmental sink
See above
Intake and uptake routes
See above
Dose effects/dosimetry
Species-specific considerations
See above. It should be remembered that manybeta emitters are also strong gamma emitters.
Species-specific considerations
See above
T
In some circumstances, enquiry can establish that total beta actually relates to a limited number ofradionuclides. If this is the case, reference can be made to radionuclide-specific datasheets. The generalcategory of total beta without further characterisation is of little utility.
Terrestrial Aquatic Atmospheric
Environment Agency Radionuclides Handbook190
Name
Radioactivehalf-life
Parent
Uranium-234
2.45 x 105 yrs
Pa-234m,Pu-238
Symbol
Principal decaymode
Daughter
U-234
Alpha
Th-230 [R]
Origin
Grouping
Detection
Primordial
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• From the decay of Pu-238• From the decay of Pa-234m in the U-238 chain
Uses • Mainly for research purposes
Modes Land• Disposed uranium mill tailings and debris;• From naturally occurring U-234 in soil and rocks• Treatment, reprocessing and disposal of spent fuel
ofAir
• Treatment, reprocessing and disposal of spent fuel• From burning coal
releaseWater • Treatment, reprocessing and disposal of spent fuel
Speciation
Uranium can exist in any one of four oxidationstates, with the +4 state being favoured inreducing conditions and the +6 state in oxidisingconditions.
Uranium forms a wide range of halide and oxidecompounds.
The hydroxide and carbonate are also known anduranium can participate in the formation oforganic complexes.
Analogue species
The chemical, biochemical and biogeochemicalproperties of uranium are quite distinct from thoseof the other actinide elements and there is a greatdeal of information on its environmentalbehaviour.
For this reason, there is no requirement to identifyanalogue elements.
U
Environment Agency Radionuclides Handbook 191
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Uranium is not stronglyadsorbed to soils.
However, its behaviour is redoxsensitive and it can accumulatein reducing horizons.
In general, it is stronglyexcluded from plants
Aquatic
Uranium behaves conservativelyin aqueous environments.
It is not strongly accumulatedby aquatic organisms.
Atmospheric
U-234 released to atmospherewould be expected to disperseas an aerosol.
Chemical forms could includeUO2, U3O8 and UF4. In addition,the toxic gas UF6 could bereleased.
Environmental sink
U-234 is produced in theenvironment from U-238.Almost all of this uraniumremains at its site of productionuntil it decays.
However, U-234 entering theenvironment due to humanactivities may be more mobile,migrating with groundwatersand surface waters until itreaches the aqueousenvironment.
Intake and uptake routes
In general, uranium is strongly excluded from plants, although cerealcrops can show a degree of accumulation of uranium.
Uranium is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically 1%-2 %. Mineral bone is theprincipal site of accumulation.
Concentration ratios relative to water are about 10 for freshwaterand marine fish and crustaceans. Concentration ratios for molluscscan be a little higher (~30) and values ~100 are typical of marineplants.
Dose effects/dosimetry
U-234 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, U-234 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Note that uranium is chemically toxic as well asposing a radiation hazard.
Species-specific considerations
No major species-specific considerations have beenidentified.
U
Environment Agency Radionuclides Handbook192
Name
Radioactivehalf-life
Parent
Uranium-235
7.04 x 108 yrs
Pu-239
Symbol
Principal decaymode
Daughter
U-235
Alpha
Th-231 [R]
Origin
Grouping
Detection
Primordial
Natural
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Naturally during the formation of the Universe
Uses • As a basic fuel for nuclear fission reactors
ModesLand • Treatment and disposal of spent fuel
of Air• Treatment and disposal of spent fuel• From burning coal
releaseWater • Treatment and disposal of spent fuel
Speciation
Uranium can exist in any one of four oxidationstates, with the +4 state being favoured inreducing conditions and the +6 state in oxidisingconditions.
Uranium forms a wide range of halide and oxidecompounds.
The hydroxide and carbonate are also known anduranium can participate in the formation oforganic complexes.
Analogue species
The chemical, biochemical and biogeochemicalproperties of uranium are quite distinct from thoseof the other actinide elements and there is a greatdeal of information on its environmentalbehaviour.
For this reason, there is no requirement to identifyanalogue elements.
U
Environment Agency Radionuclides Handbook 193
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Uranium is not stronglyadsorbed to soils.
However, its behaviour is redoxsensitive and it can accumulatein reducing horizons.
Aquatic
Uranium behaves conservativelyin aqueous environments.
It is not strongly accumulatedby aquatic organisms.
Atmospheric
U-235 released to atmospherewould be expected to disperseas an aerosol.
Chemical forms could includeUO2, U3O8 and UF4. In addition,the toxic gas UF6 could bereleased.
Environmental sink
U-235 is a primordialradionuclide widely distributedin rocks, soils and sediments.
As it is incorporated in themineral phase, it tends toremain in situ.
U-235 entering theenvironment due to humanactivities may be more mobile.
Intake and uptake routes
In general, uranium is strongly excluded from plants, although cerealcrops can show a degree of accumulation of uranium.
Uranium is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically 1%-2 %. Mineral bone is theprincipal site of accumulation.
Concentration ratios relative to water are about 10 for freshwaterand marine fish and crustaceans. Concentration ratios for molluscscan be a little higher (~30) and values ~100 are typical of marineplants.
Dose effects/dosimetry
U-235 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, U-235 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Note that uranium is chemically toxic as well asposing a radiation hazard.
Species-specific considerations
No species-specific considerations
U
Environment Agency Radionuclides Handbook194
Name
Radioactivehalf-life
Parent
Uranium-238
4.47 x 1010 yrs
Pu-242
Symbol
Principal decaymode
Daughter
U-238
Alpha
Th-234 [R]
Origin
Grouping
Detection
Natural
Primordial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Naturally during the formation of the Universe
Uses• As the starting point for production of Pu-239• For the production of armour-piercing munitions
Modes Land• Disposed uranium mill tailings and debris• From naturally occurring U-238 in soil and rocks• Treatment, reprocessing and disposal of spent fuel
ofAir
• Treatment, reprocessing and disposal of spent fuel• From burning coal
releaseWater • Treatment, reprocessing and disposal of spent fuel
Speciation
Uranium can exist in any one of four oxidationstates, with the +4 state being favoured inreducing conditions and the +6 state in oxidisingconditions.
Uranium forms a wide range of halide and oxidecompounds.
The hydroxide and carbonate are also known anduranium can participate in the formation oforganic complexes.
Analogue species
The chemical, biochemical and biogeochemicalproperties of uranium are quite distinct from thoseof the other actinide elements and there is a greatdeal of information on its environmentalbehaviour.
For this reason, there is no requirement to identifyanalogue elements.
U
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Uranium is not stronglyadsorbed to soils.
However, its behaviour is redoxsensitive and it can accumulatein reducing horizons.
In general, it is stronglyexcluded from plants
Aquatic
Uranium behaves conservativelyin aqueous environments.
It is not strongly accumulatedby aquatic organisms.
Atmospheric
U-238 released to atmospherewould be expected to disperseas an aerosol.
Chemical forms could includeUO2, U3O8 and UF4. In addition,the toxic gas UF6 could bereleased.
Environmental sink
U-238 is a primordialradionuclide widely distributedin rocks, soils and sediments.
As it is incorporated in themineral phase, it tends toremain in situ.
U-238 entering theenvironment due to humanactivities may be more mobile.
Intake and uptake routes
In general, uranium is strongly excluded from plants, although cerealcrops can show a degree of accumulation of uranium.
Uranium is not very bioavailable to animals. The fractionalgastrointestinal absorption is typically 1%-2 %. Mineral bone is theprincipal site of accumulation.
Concentration ratios relative to water are about 10 for freshwaterand marine fish and crustaceans. Concentration ratios for molluscscan be a little higher (~30) and values ~100 are typical of marineplants.
Dose effects/dosimetry
U-238 is primarily an alpha emitter.
Activity deposited on the outer layers oforganisms (e.g. skin) will therefore be of littleradiological consequence.
Therefore, U-238 is of greatest potentialsignificance when internally incorporated inorgans and tissues that are susceptible to theeffects of alpha radiation.
Note that uranium is chemically toxic as well asposing a radiation hazard.
Species-specific considerations
No species-specific considerations
U
Environment Agency Radionuclides Handbook196
Name
Radioactivehalf-life
Parent
Vanadium-48
16.2 days
N/A
Symbol
Principal decaymode
Daughter
V-48
EC
Ti-48
Origin
Grouping
Detection
Activation
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Irradiation of non-radioactive precursors in a cyclotron or nuclear reactor
Uses• Certain medical applications, for example delivering radiation doses to arteries
inside a stent (mesh container)
Modes Land • Sewage sludge application to land
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Vanadium is a transition metal that can showoxidation states from -1 through to +5.
It forms sulphate, oxide and halide compounds.
Because of the ability to hold different oxidationstates, there are several different forms ofsulphate, oxide and halide compounds.
Analogue species
There have been extensive studies on thedistribution and transport of vanadium in theenvironment.
Therefore, it is not appropriate to identify anyanalogues.
V
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Relative to other metals, V isfairly mobile in neutral oralkaline soils, but its mobility islower in acid soils.
Mobility is much higher inoxidising than in reducingconditions.
Aquatic
In freshwater, V-48 is likely to bepresent as V4+ under reducingconditions and V5+ underoxidising conditions.
Both species are known to bindstrongly to mineral or biogenicsurfaces.
In the oceans, most V isremoved from the water columnby deposition.
Atmospheric
If V-48 is released toatmosphere, it will be in theform of an aerosol.
Environmental sink
Because of its short half-life, V-48 in terrestrial environmentsis likely to decay in situ.
In aquatic systems, V-48 willdecay both in the water columnand in deposited sediments.
Intake and uptake routes
V-48 in the terrestrial environment is likely to be present mainly onthe external surfaces of plants following deposition from theatmosphere.
Vanadium is of limited bioavailability to animals and the fractionalgastrointestinal absorption is ~1 %.
Vanadium entering the systemic circulation is preferentially depositedin the skeleton of mammals.
Marine plants and invertebrates contain higher concentrations ofvanadium than terrestrial plants and animals.
Dose effects/dosimetry
V-48 emits energetic gamma rays.
Because of its short half-life and limitedbioavailability to many plants and animals interrestrial environments, external irradiation maybe of greater significance than internal irradiation.
Similarly, external irradiation from materialadsorbed to external surfaces of organisms may beimportant in the aquatic environment.
Species-specific considerations
There are specific species of higher plants andfungi that accumulate stable V. These may alsoaccumulate V-48.
V
Environment Agency Radionuclides Handbook198
Name
Radioactivehalf-life
Parent
Xenon-133
5.2 days
N/A
Symbol
Principal decaymode
Daughter
Xe-133
Beta
Cs-133
Origin
Grouping
Detection
Fission
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production • Produced during fission in a nuclear reactor
Uses • Occasionally used in medicine for diagnostic imaging
Modes Land • Not generally released to land
of Air • During treatment and disposal of spent fuel
release Water • Not generally released to water
Speciation
Xenon is a noble gas and, as such, forms only alimited number of chemical compounds due to itslack of reactivity.
One such example is XeF2.
Analogue species
All the noble gases (Ne, Ar, Kr, Xe and Rn) exhibitsimilar environmental behaviour.
Rn is a special case because it is generated in theenvironment from isotopes of radium and becauseit decays to produce chemically reactive, short-lived and long-lived radioactive progeny.
Rn is therefore not an appropriate analogue for Xe.
X
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Xe-133 is not transferredsignificantly to the terrestrialenvironment.
Aquatic
Xe-133 is not transferredsignificantly to the aquaticenvironment.
Atmospheric
Xe-133 is almost exclusivelyreleased to the atmosphere.
Its short radioactive half-life andlow reactivity means that itdecays almost entirely duringatmospheric transport and is nottransferred significantly to otherenvironmental media.
Environmental sink
No major sink, owing to its lackof reactivity and short half-life.
Intake and uptake routes
Xe-133 is sparingly soluble in body tissues, notably those with a highfat content. However, it is not metabolised.
Some Xe-133 will be present in the lungs in inhaled air.
Dose effects/dosimetry
Xe-133 emits beta particles and low energygamma rays.
Radiation doses to organisms arise mainly due toexternal beta and gamma irradiation, irradiation ofthe lungs of animals from contained gas andinternal irradiation from gas dissolved in tissues.
Species-specific considerations
Because Xe-133 is not metabolised to anysignificant degree, there are no major species-dependent considerations.
X
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Name
Radioactivehalf-life
Parent
Yttrium-90
64 hours
Sr-90
Symbol
Principal decaymode
Daughter
Y-90
Beta
Zr-90
Origin
Grouping
Detection
Radiogenic
Artificial
Laboratory
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Produced during fission in a nuclear reactor• From decay of strontium-90, another important fission isotope
Uses • In medicine for the treatment of cancer and arthritis
Modes Land • Sewage sludge application to land, but would probably decay away before this can occur
of Air • Not generally released to air
release Water • Hospital releases to sewers
Speciation
Yttrium is a transition metal that only formscompounds in the +3 oxidation state.
The chemistry of yttrium is very similar to that ofthe rare earths.
As such, yttrium forms compounds withhydrogen, oxygen and the halides. It also forms anumber of stable complexes.
Analogue species
Ce is the most studied of the rare earths andprovides a good analogue for the behaviour of Y-90.
However, in the environment, Y-90 is usuallypresent as a result of the decay of Sr-90 and itsbehaviour is often determined by that of itsparent.
Y
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Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Y-90 is highly particle reactiveand would tend to bind tosurfaces when produced.
Aquatic
In aquatic environments, Y-90produced from Sr-90 wouldtend to be particle reactive andwould, therefore, tend tomigrate from the water columnby deposition
Atmospheric
If Y-90 were released to theatmosphere, it would be in theform of an aerosol.
Environmental sink
In general, the short half-lifeand limited mobility of Y-90 willmean that it decays close to itspoint of production.
Intake and uptake routes
In plants and animals, Y-90 is likely to be present in concentrationsthat are close to secular equilibrium with those of Sr-90.
With the assumption of secular equilibrium, intake and uptake routesfor Y-90 are of limited importance.
As with Sr-90, high concentrations are likely to be found in theskeleton.
Dose effects/dosimetry
Y-90 is a pure beta emitter.
Under the assumption of secular equilibrium, aconvenient approach to dosimetry is to assign theY-90 beta energy to its parent Sr-90.
Species-specific considerations
As for Sr-90
Y
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Name
Radioactivehalf-life
Parent
Zirconium-95
64 days
N/A
Symbol
Principal decaymode
Daughter
Zr-95
Beta [gamma]
Nb-95 [R]
Origin
Grouping
Detection
Fission
Artificial
In situ
Production, uses and modes of release
Decay modes
Chemical properties/characteristics
Production• Produced during fission in a nuclear reactor• Irradiation of zirconium cladding with neutrons in a nuclear reactor
Uses • No specific uses outsides research activities
ModesLand • During treatment and disposal of spent fuel
ofAir • During treatment and disposal of spent fuel
release Water• During treatment and disposal of spent fuel• Liquid discharges from nuclear facilities
Speciation
The most important oxidation state for zirconiumin aqueous solution is +4.
However, the Zr4+ ion is only soluble in strong(laboratory) acid solutions (pH <1).
In water, zirconium hydrolyses very easily to formhydroxo complexes, unless in the form of the verystable fluoride.
Analogue species
There are chemical, biochemical andbiogeochemical similarities between Zr and Nb.
However, both elements have been studied to asimilar degree and there is little merit in treatingZr as an analogue of Nb or vice versa.
Z
Environment Agency Radionuclides Handbook 203
Behaviour in the environment
Exposure routes and pathways
Effects on organisms
Terrestrial
Zr-95 is highly particle reactive.
It will therefore tend to remainin situ, rather than migratingthrough the terrestrialenvironment in surface orgroundwaters.
Aquatic
Zr-95 is highly particle reactivein marine systems.
In freshwater systems, it hasmoderate to high particlereactivity.
However, even in marinesystems, a significant fraction ofthe Zr-95 may be associatedwith colloids or dissolvedorganic matter complexes.
Atmospheric
If Zr-95 were released to theatmosphere, it would disperse asan aerosol.
Environmental sink
Zr-95 will generally decay closeto its point of deposition in theterrestrial environment.
In aquatic systems, Zr-95 willinteract with mineral sediments,colloids and dissolved organicmatter.
Some will be transferred tobottom sediments and decaywill occur there or in the watercolumn.
Intake and uptake routes
Zr-95 is strongly excluded from plants.
It is also not very bioavailable to animals, with a fractionalgastrointestinal absorption of ~0.2 %, although this may beincreased in pre-weaned juveniles.
Zr-95 that enters systemic circulation is widely dispersed in softtissues, but the main reservoir of uptake and long-term retention ismineral bone.
Concentration ratios relative to water are about 20 for freshwaterand marine fish, but can be >1,000 for marine invertebrates andseaweed.
Dose effects/dosimetry
Zr-95 has a high yield of energetic gamma rays.
Because of its low bioavailability in terrestrialenvironments, external irradiation is likely to be ofgreater significance than internal irradiation.
External irradiation may also be of greatestimportance in the aquatic environment.
Species-specific considerations
The main species-specific consideration is thepartitioning of Zr-95 in marine invertebratesbetween adsorbed, unassimilated particulate andtissue uptake fractions.
Z
Glossary
This glossary defines some of the terms used in thispublication, but also replicates entries from theglossary found in Copplestone et al. (2001). Othersources, e.g. IAEA (2000), provide a more extensivelist of definitions.
AberrationDeparture from normal.
Absorbed doseQuantity of energy imparted by ionising radiationto unit mass of matter such as tissue. Unit Gray,symbol Gy. 1Gy = 1 joule per kilogram.
ActinidesA group of 15 elements with atomic number fromthat of actinum (89) to lawrencium (103) inclusiveand analogous to the so-called lanthanide series ofrare earth metals. All are radioactive. In general,the actinides are highly particle reactive and arenot taken up easily by plants or animals.Nevertheless, they are generally very radiotoxic.
ActivationThe process in which non-radioactive elements areconverted to radioactive elements as a result ofexposure to radiation in a nuclear reactor orweapon explosion. An example is the formation oftechetium-99m for medical purposes fromirradiation of molydenum-99.
ActivityAttribute of an amount of a radionuclide.Describes the rate at which transformations occurin it. Unit Becquerel, symbol Bq. 1Bq = 1 transformation per second.
Acute exposureExposure received within a short period of time.Normally used to refer to exposure of sufficientlyshort duration that the resulting dose can betreated as instantaneous (e.g. less than an hour).Usually contrasted with chronic and transitoryexposure.
AdsorbUsually a solid holding molecules (of a gas orliquid, etc.) to its surface, forming a thin film.
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Advanced gas cooled reactorA development of the Magnox reactor, usingenriched uranium oxide fuel in stainless steelcladding.
AerosolA suspension of fine solid or liquid particles in gas.Smoke, fog, and mist are examples of aerosols.
Alpha particleA particle consisting of two protons plus twoneutrons, i.e. fast-moving helium nuclei (atomicmass of 4 and atomic number 2). Emitted by aradionuclide.
AllotropyThe ability of certain elements and compounds(e.g. phosphorus) to show two or more distinctphysical forms in the same physical state (e.g.solid).
AntineutrinoA particle without mass or charge that is emittedfrom the nucleus, along with an electron, duringbeta decay.
ApoptosisApoptosis or programmed cell death occursnaturally during the development andmaintenance of animal tissues and organs. Duringthese processes, more cells are produced than arerequired for building tissues and organs. Theunwanted cells are programmed to die eitherbecause the chemical signals that direct them togo on living are suppressed or because they receivea specific signal to die.
AtomThe smallest portion of an element that cancombine chemically with other atoms.
Atomic massThe mass of an atomic nucleus, usually denoted bythe symbol A.
Atomic numberThe number of protons within an atomic nucleus,usually denoted by the symbol Z.
Auger electronA low-energy electron ejected from an atomfollowing the transition of another electron from ahigher to lower energy state.
AuthorisationThe granting by a regulatory body or othergovernmental body of written permission for anoperator to perform specified activities.
BackgroundThe dose or dose rate (or an observed measurerelated to the dose or dose rate), attributable to allsources other than the one(s) specified.
Becquerel (Bq)See activity.
Benthic invertebrateAquatic invertebrate living on or in sediment.
BenthosSynonym for community of benthic invertebrate.
Beta particleA negatively charged (electron) or positivelycharged (positron) particle emitted from thenucleus of an atom during radioactive decay.Often loosely assumed to be the negativelycharged particle.
BioavailabilityThe degree and rate at which a substance isabsorbed into a living system or is made availableat the site of physiological activity.
BiomarkerA biological response to an environmentalpollutant, which gives a measure of exposure. Theresponse may be molecular, cellular or wholeorganism.
BiotaA collective term for the flora and fauna.
Breeding (in radiation term)The production of one radionuclide from anotherdue to the action of incident atomic particles, e.g.the production of plutonium-239 from uranium-238.
ChromatidWhen a chromosome becomes shorter and thickerduring the first stage of mitosis it is seen tobecome a double thread. Each thread is achromatid.
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Chromosome translocationSporadic and random fusion of part of onechromosome onto part of another.
ChromosomesRod-shaped bodies found in the nucleus of cells inthe body. They contain the genes or hereditaryconstituents. Each chromosome has acharacteristic length and banding pattern.
Chronic exposureExposure persisting in time. Normally used to referto continuous exposures to low concentrations ofpollutants. See also transitory and acute exposure.
Concentration factor (CF)Ratio of element or nuclide in the consumer (or aspecific tissue or organ etc.), to that in what isconsumed, or to that in the environmentalmedium.
Cosmic radiationHigh energy ionising radiation from outer space.
CosmogenicDenoting radionuclides produced in the upperatmosphere due to the action of cosmic rays.
Critical groupSub-group of the public most affected by a givenrelease of radioactivity.
Critical organThe organ or tissue the irradiation of whichpresents the greatest threat to the health of theindividual.
Critical pathwayThe pathway that leads to the greatest dose ofradiation. An example would be the air-grass-cow-milk pathway, important for iodine isotopesreleased into the air.
CyclotronAn apparatus for producing high-energy atomicparticles.
Cytogenetic damageDamage to chromosomes that can be detected onthe microscopic level. Examples of damageinclude deletions, translocations and micronuclei.
DecayThe process of spontaneous transformation of aradionuclide. The decrease in the activity of aradioactive substance.
Decay productA nuclide or radionuclide produced by decay. Itmay be formed directly from a radionuclide or as aresult of a series of successive decays throughseveral radionuclides.
DecommissioningThe process of closing down a nuclear reactor,removing the spent fuel, dismantling some of theother components, and preparing them fordisposal. Term may also be applied to other majornuclear facilities.
DepositionThe settling of particles from the atmosphere tothe ground or plant surfaces. Deposition can bewet (e.g. through rainfall) or dry.
Deterministic effectA radiation effect for which generally a thresholdlevel of dose exists above which the severity of theeffect is greater for a higher dose.
DisposalIn relation to radioactive waste, dispersal oremplacement in any medium without the intentionof retrieval.
DNADeoxyribonucleic acid. The compound thatcontrols the structure and function of cells and isthe material of inheritance.
DoseGeneral term for quantity of ionising radiation.See absorbed dose, equivalent dose and effectivedose. Frequently used for effective dose.
Dose assessmentAssessment of the dose(s) to an individual or groupof people.
Dose rateDose released over a specified unit of time.
Effective doseThe quantity obtained by multiplying theequivalent dose to various tissues and organs by aweighting factor appropriate to each and summingthe products. Unit Sievert, symbol Sv. Frequentlyabbreviated to dose.
Electromagnetic radiationRadiation consisting of electric and magnetic wavesthat travel at the speed of light. Examples: light,radio waves, gamma rays, x-rays.
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ElectronThe electron is a small atomic particle with 1 unitof negative electric charge and a mass of 1/1836 of aproton. Every atom consists of one nucleus andone or more electrons in orbit around the nucleus.Positively charged electrons, called positrons, alsoexist. See also beta particle.
Electron capture (EC)A form of radioactive decay in which the nucleuscaptures an orbiting electron, converting a protonto a neutron, the energy being released as X-rays(or Auger electrons).
Electron voltUnit of energy employed in radiation physics.Equal to the energy gained by an electron inpassing through a potential difference of 1 volt.Symbol eV. 1eV = ~1.6 x 10-19 joule.
Embryo (in animals)The stage of development between the time thatthe fertilised egg begins to divide and thedeveloping animal hatches or is born.
Embryo (in plants)The part of a seed which develops into the root(radicle) and shoot (plumule) of a plant.
EmbryogenesisThe processes leading to the development of anembryo.
Endpoint1. The final stage of a process, especially the pointat which an effect is observed.2. A radiological or other measure of protection orsafety that is the calculated result of an analysis orassessment.
Enriched uraniumUranium in which the content of the isotopeuranium-235 has been increased above its naturalvalue of 0.7 % by weight.
Equivalent doseThe quantity obtained by multiplying the absorbeddose by a weighting factor (radiation weightingfactor) to allow for the different effectiveness of thevarious ionising radiation in causing harm to tissue.Unit Sievert, symbol Sv.
FalloutThe transfer of radionuclides produced by nuclearweapons from the atmosphere to earth; thematerial transferred.
FecundityThe number of viable offspring produced by anorganism; mature seeds produced, eggs laid, orlive offspring delivered, excluding fertilisedembryos that have failed to develop.
FertilityIn sexually reproducing plants and animals, it is thenumber of fertilised eggs produced in a given time.
FissionNuclear fission. A process in which a nucleus splitsinto two or more nuclei and energy is released.Frequently refers to the splitting of a nucleus ofuranium-235 into two approximately equal partsby a thermal neutron with emission of one or moreneutrons and the release of energy.
Fission productsThe atoms formed as a result of nuclear fission, e.g.caesium-137, iodine-131, strontium-90, cerium-144.
FoetusThe developing embryo is known as a foetus onceit can be recognised as a species.
Free radicalA grouping of atoms that normally exists incombination with other atoms but can sometimesexist independently. Generally very reactive in achemical sense.
GametesThe sex cells which fuse together at fertilisation toform the zygote. In animals, the gametes are thesperm in males and the ovum (egg) in females. Inplants, the gametes are the pollen in the male andthe ovules in the female.
GametogenesisProcess leading to the production of gametes.
Gamma radiationVery penetrating electromagnetic radiation,without mass or charge, frequently emitted fromthe nucleus of an atom during radioactive decay.Emitted by a radionuclide.
GenesThe biological units of heredity. They are arrangedalong the length of chromosomes.
GenotoxicityAbility to cause damage to genetic material. Suchdamage may be mutagenic and/or carcinogenic.
Environment Agency Radionuclides Handbook 207
Germ cellCell specialised to produce gametes. The germ cellline is often formed very early in embryonicdevelopment.
GestationThe process of being carried in the womb, fromconception to birth.
Gray (Gy)See absorbed dose.
High level waste (HLW)The radioactive liquid containing most of thefission products and actinides present in spent fuel,which forms the residue from the first solventextraction cycle in reprocessing, and some of theassociated waste streams. The term is also usedfor: this material following solidification; spent fuel(if it is declared a waste); or any other waste withsimilar radiological characteristics.
ImplantationWhen an embryo passes from the oviduct to theuterus, it becomes attached to the uterine wall.
Indicator speciesA species that only thrives under certainenvironmental conditions and whose presenceshows that these conditions are present.
Inert gasA member of the family of gaseous chemicalelements characterised by their extreme lack ofreactivity. The inert gases are: helium, neon,argon, krypton, xenon and radon.
IonAn atom or group of atoms that carries a netelectrical charge - either positive or negative.
IonisationThe process by which a neutral atom or moleculeacquires or loses an electric charge. Theproduction of ions.
Ionising radiationRadiation that produces ionisation in matter.Examples are alpha particles, gamma rays, X-raysand neutrons. When these pass through thetissues of the body, they have sufficient energy todamage DNA.
IrradiationExposed to radiation.
Isomeric transformation (IT)A form of radioactive decay in which a metastablenucleus decays with the release of energy asgamma rays.
IsomersIn this context, nuclides having the same numberof protons and neutrons in their nucleus but indifferent energy states.
IsotopeNuclides with the same number of protons butdifferent numbers of neutrons. Not a synonym fornuclide.
KaryotypeThe complete set of chromosomes of a cell ororganism.
LanthanidesThe group of elements with atomic numbersbetween Z = 57 and Z = 70. They have similarchemical properties and are highly particlereactive.
LD50
The dose that causes mortality in 50 % of theorganisms tested.
Linear energy transfer (LET)A measure of how, as a function of distance,energy is transferred from radiation to the exposedmatter. Radiation with high LET is normallyassumed to comprise of protons, neutrons andalpha particles (or other particles of similar orgreater mass). Radiation with low LET is assumedto comprise of photons (including X-rays andgamma rays), electrons and positrons.
Low and intermediate level waste (LLW and ILW)Radioactive waste with radiological characteristicsbetween those of exempt waste and high levelwaste. These may be long-lived waste (LILW-LL) orshort-lived waste (LILW-SL).
Magnox reactorA thermal reactor named after the magnesiumalloy in which the uranium metal fuel is contained.The moderator is graphite and the coolant iscarbon dioxide gas.
MeiosisA form of nuclear division in which each daughtercell receives only one of each homologouschromosome pair. Meiosis occurs during theformation of gametes.
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MetabolismThe chemical changes in living cells by whichenergy is provided for vital processes and activitiesand new material is assimilated.
MitosisA type of cell division by which two daughter cellsare produced from one parent cell, with no changein the number of chromosomes.
ModeratorA material used in nuclear reactors to reduce theenergy and speed of the neutrons produced as aresult of fission.
MoleculeThe smallest portion of a substance that can existby itself and retain the properties of the substance.
MorbidityThe state of being diseased.
MorphogenesisThe process of ëshape formationí: the processesthat are responsible for producing the complexshapes of adults from the simple ball of cells thatderives from division of the fertilised egg.
MutationA change in the genetic material of an organism.This can be spontaneous or induced by chemicalsor radiation.
Naturally occurring radionuclidesRadionuclides that occur naturally in significantquantities on Earth.
NeutrinoA particle without mass or charge that is emittedfrom the nucleus, along with a positron, duringbeta decay.
NeutronA fundamental nuclear particle of mass 1 and zeroelectric charge.
Non-ionising radiationRadiation that does not produce ionisation inmatter. Examples are ultraviolet radiation, light,infrared radiation and radio-frequency radiation.When these radiation pass through the tissues ofthe body, they do not have sufficient energy todamage DNA directly.
Non-nuclear licensed siteA non-nuclear licensed site (or non-nuclear site) iswhere the handling, use and discharge ofradioactive substances may occur but not as themain activity. This includes research institutions,hospitals, defence establishments, etc.
Nuclear fuel cycleThe stages in which the fuel for nuclear reactors isfirst prepared, then used, and later reprocessed forpossible use again. Waste management is alsoconsidered part of the cycle.
Nuclear licensed siteA nuclear licensed site (or nuclear site) holds anoperating licence under the Nuclear InstallationsAct 1965; the handling or use of radioactivematerials is the main activity.
Nuclear powerPower obtained from the operation of a nuclearreactor.
Nuclear reactorA device in which nuclear fission can be sustainedin a self-supporting chain reaction involvingneutrons. In thermal reactors, fission is broughtabout by thermal neutrons.
Nuclear weaponExplosive device deriving its power from fission orfusion of nuclei or from both.
Nucleus (of atom)The core of an atom, occupying little of thevolume, containing most of the mass, and bearingpositive electric charge.
Nucleus (of cell)The central part of a cell containing chromosomesand the genetic information bound in DNA.
NuclideA species of atom distinguished by its particularnumber of protons and number of neutrons.
OocyteThe developing female gamete before maturationand release.
OrganogenesisThe process of formation of specific organs in aplant or animal involving morphogenesis anddifferentiation.
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OrganometallicAn organic compound that contains a metal ormetalloid element bonded directly to carbon.
Oxidation numberThe number of electrons that must be added to apositive ion, or removed from a negative ion, toproduce a neutral atom. Thus, for example, forvanadium in an oxidation state of +5, five electronsmust be added to produce neutral vanadium.
Pelagic biotaAquatic organisms living in the water column of abody of water, rather than along the shore or inthe bottom sediments.
PhotonA quantum of electromagnetic radiation.
PhotosynthesisThe formation of carbohydrates from carbondioxide and a source of hydrogen (e.g. water) inthe chlorophyll-containing tissues of plantsexposed to light.
PositronA positively charged beta+ particle. Positronsrapidly interact with negatively charged electrons,releasing two gamma ray photons.
Pressurised water reactor (PWR)A thermal reactor using water as both a moderatorand coolant. Uses enriched uranium oxide fuel.
Primordial radionuclidesRadionuclides left over from the creation of theuniverse. They necessarily have very long half-lives, e.g. uranium-238 and thorium-232.
ProgenyAtomic nuclei produced from the radioactive decayof parent nuclei. Same as ëdaughtersí.
ProtonA fundamental nuclear particle with mass of1.672614 x 10-27 kg and positive electric charge of1. The proton is in effect a hydrogen nucleus.
RadiationThe emission and propagation of energy throughspace or through a material medium in the form ofwaves. The term may be extended to includestreams of sub-atomic particles such as alpha andbeta particles as well as electromagnetic radiation.Frequently used for ionising radiation, except whenit is necessary to avoid confusion with non-ionisingradiation.
Radiation weighting factor (wr)wr values (radiation weighting factors) representthe relative biological effectiveness of the differentradiation types, relative to X- or gamma rays, inproducing endpoints of ecological significance.
RadioactiveThe term used to describe an element thatundergoes radioactive decay.
Radioactive half-lifeThe time taken for half of the atoms of aradioactive element to decay. Each radioisotopehas a unique half-life. The half-life is a constantwhich is unaffected by any physical conditionssuch as temperature or pressure. Symbol T1/2.
Radioactive wasteUseless material containing radionuclides.Frequently categorised in the nuclear powerindustry according to activity and other criteria, aslow level, intermediate level, and high level waste.
RadiobiologyThe study of the effects of ionising radiation onliving things.
RadiogenicA term applied to radionuclides that arise from thedecay of other radionuclides.
Radiological protectionThe science and practice of limiting the harm tohuman beings from radiation.
RadionuclideAn unstable nuclide that emits ionising radiation.
Regulatory bodyAn authority or a system of authorities designatedby the government of a state as having legalauthority for conducting the regulatory process,including issuing authorisations and therebyregulating nuclear processes, radiation, radioactivewaste and transport safety.
Environment Agency Radionuclides Handbook210
Relative Biological Effectiveness (RBE)A relative measure of the effectiveness of differentradiation types at inducing a specified healtheffect, expressed as the inverse ratio of theabsorbed doses of two different radiation typesthat would produce the same degree of a definedbiological endpoint.
ReprocessingA process or operation, the purpose of which is toextract radioactive isotopes from spent fuel forfurther use.
RespirationThe process by which organic compounds ofcarbon in plant and animal tissue are broken downto carbon dioxide and water, at the same timereleasing energy.
RiskA measure of the probability and extent of harm.
SievertSee effective dose.
Somatic cellsSoma, from the Greek meaning body. All bodycells except the gametes and the cells from whichthe gametes develop.
Spent fuelNuclear fuel removed from a reactor followingirradiation, which is no longer useable in itspresent form because of depletion of fissilematerial, poison build-up or radiation damage.
SpermatocytesCells of the male reproductive system.
Stem cellA cell that upon division produces dissimilardaughters, one replacing the original stem cell, theother differentiating further (e.g. meristems ofplants).
Stochastic effectA radiation-induced health effect, the probability ofoccurrence of which is greater for a higherradiation dose and the severity of, which (if itoccurs) is independent of dose.
Taxon (taxa)A member of a formal classification of plants andanimals according to their presumed naturalrelationships.
TelomereThe end of a chromosome.
Transitory exposureExposure that is too protracted to be described asacute exposure, but does not persist for manyyears, is sometimes described as transitoryexposure.
Transuranic elementElements of atomic number greater than that ofuranium (atomic number 92). Examples areneptunium, plutonium, curium and americium
Wash-offThe removal of radionuclides from plant surfaces tothe ground through the action of precipitation.
X-rayA discrete quantity of electromagnetic energywithout mass or charge, with less energy thangamma rays. They can be produced by the actionof an electron beam on a metal target. They areemitted by some processes in radioactive decay.
Environment Agency Radionuclides Handbook 211
Environment Agency Radionuclides Handbook212
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