Quantification of Radionuclide Transfer in Terrestrial and Freshwater Environments for Radiological Assessments | IAEA

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IAEA-TECDOC-1616

Quantification of Radionuclide

Transfer in Terrestrial

and Freshwater Environments

for Radiological Assessments

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The originating Section of this publication in the IAEA was:

Chemistry Unit, Agency’s Laboratories, Seibersdorf International Atomic Energy Agency

Wagramer Strasse 5 P.O. Box 100 A-1400 Vienna, Austria

QUANTIFICATION OF RADIONUCLIDE TRANSFER IN TERRESTRIAL AND FRESHWATER ENVIRONMENTS FOR RADIOLOGICAL ASSESSMENTS

IAEA, VIENNA, 2009 ISBN 978–92–0–104509–6

ISSN 1011–4289

Printed by the IAEA in Austria May 2009

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FOREWORD

For more than thirty years, the IAEA has published a set of documents aimed at the limitation of the radiation exposure of the population from various nuclear activities. In particular, in 1994 the IAEA published Technical Reports Series No. 364, Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environments. Over the years, it has proved to be a valuable reference for radioecologists, modellers and authorities in Member States, and has been quoted in numerous impact assessments.

Technical Reports Series No. 364 was based on a review of available data up to the end of 1992. However, a number of high quality critical reviews have been produced in recent years for some of the transfer parameter values which merit consideration. Thus, it was assumed that there is sufficient new information available to warrant reconsideration of a significant proportion of the values given in Technical Reports Series No. 364 and to initiate an updating of Technical Reports Series No. 364 in the framework of the IAEA EMRAS (Environmental Modelling for RAdiation Safety) project. It is expected that the revision of Technical Reports Series No. 364 will initiate further updating of related IAEA publications, and international and national radiological models.

The present IAEA-TECDOC is intended to be a support to the update of Technical Reports Series No. 364, overcoming the limitations of the former, and comprises both revised transfer parameter values, as well as missing data, key transfer processes, concepts and models that were found to be important for radiation safety.

The publication was prepared by members of the EMRAS project Working Group 1, Theme 1 Revision of IAEA Technical Reports Series No. 364. The group was chaired initially by P. Santucci, followed by P. Calmon. The IAEA wishes to express its gratitude to M. Thorne, A.

Gondin da Fonseca and B.Varga for their kind assistance in editing and preparation of the document for publishing, and.to all the contributors to the IAEA-TECDOC and those who assisted in its drafting and review. The IAEA officer responsible for this publication was S. Fesenko of the Department of Nuclear Sciences and Applications.

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EDITORIAL NOTE

The papers in these proceedings are reproduced as submitted by the authors and have not undergone rigorous editorial review by the IAEA.

The views expressed do not necessarily reflect those of the IAEA, the governments of the nominating Member States or the nominating organizations.

The use of particular designations of countries or territories does not imply any judgement by the publisher, the IAEA, as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries.

The mention of names of specific companies or products (whether or not indicated as registered) does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the IAEA.

The authors are responsible for having obtained the necessary permission for the IAEA to reproduce, translate or use material from sources already protected by copyrights.

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Each of these releases involves mainly fission and neutron activation products as well as actinides [2]. Uranium mining and fuel fabrication also involve radionuclides of the uranium, actinium and thorium decay series. In addition, some industries such as mineral sands production and processing, phosphate ore processing, coal burning and oil and gas production can generate naturally occurring radioactive materials (NORMs) as waste. Other sources of human exposure include nuclear weapon testing and radiation accidents or incidents [2].

Any radiological assessments are based on an analysis of radionuclide transport patterns and processes governing radionuclide behaviour in the environment [3]. Therefore, it is an aim of the IAEA to support Member States to enhance their capability for evaluating radionuclide transport, geochemical and biochemical enrichment, and radiation effects on human beings and other biota [1].

Radionuclides released during routine operations of nuclear installations are dispersed in the environment and often difficult and expensive to measure directly because of very low radionuclide concentrations in the Environment. As a consequence, environmental radiological impacts usually are assessed by modelling both for operating nuclear facilities and during licensing. Radioecological models also have to be used for predicting future impacts, e.g. in consequence assessments of nuclear waste repositories or in emergency response planning.

Thus, many radiation protection models need to predict transfers of a large number of radionuclides. This requires information on transfer of many less mobile radionuclides, which do not usually comprise an important component of discharges or dose. Over the years, Technical Reports Series No. 364 provided an important source of such information, and is one of the key cited sources for many models. It is thus essential that such information is kept up-to-date and that any relevant recent literature is included, especially considering the paucity of existing data sources. This, in itself, is a strong argument for revision if the information given is now known to be incorrect, inadequate (given new information available since its preparation) and incomplete.

A few years ago a revision of the IAEA Safety Series No. 57 [4] was undertaken by the IAEA with the purpose of providing simple methods for calculating doses arising from radioactive discharges into the environment for risk assessment evaluations (screening of radioactive discharges). Within the revised document, some of the default parameter values, used in the models for calculating the transfer of radionuclides in food chains to humans and contributing to ingestion dose were those given in Technical Reports Series No. 364. In the new Safety Reports Series No. 19 only conservative values are considered [5]. In contrast, in Technical Reports Series No. 364 the expected values are based on different criteria and are not intended to be conservative. Current contradictions between the two documents have been resolved in the revision of these documents and updating Technical Reports Series No. 364.

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The scope of Technical Reports Series No. 364 had three major limitations. First, the parameters given in the document were mainly limited to temperate environments. Second, it gave parameters mainly for equilibrium conditions, and, therefore, they often cannot be applied for environmental assessments in accidental situations or to situations with variable release of radionuclides into the environment. And finally, Technical Reports Series No. 364 did not provide information on transfers of some radionuclides that are of importance in waste management practice.

A specific task of the Technical Reports Series No. 364 revision was to provide reference values for the most commonly used transfer parameters in radiological assessment models.

However, some important details and recommendations on how to use these parameters were often omitted that undermined the making of relevant choices of necessary parameters. This problem is being resolved by publishing of two separate but well-linked documents i.e. the Technical Reports Series document focused on the reference information intended for radiological assessment and the IAEA-TECDOC intended for justification of radioecological information used to derive reference values, radioecological concepts and models facilitating use of reference values in specific situations.

Thus, the present IAEA-TECDOC is intended to be a supportive document for the updated Technical Reports Series No. 364 overcoming the limitations of the former document, and comprises both revised transfer parameter values, as well as missing data, key transfer processes, concepts and models that were found to be important for radiation safety.

The scope of the current document covers both main radioecological concepts on mechanisms governing radionuclide behaviour in the environment and the parameters derived from numerous radioecological studies.

2. OBJECTIVES

The main objective of this document is to provide radioecological concepts, models, parameters and data for assessing site-specific past, present and potential future radiation exposures of humans and other biota in terrestrial and freshwater environments in different climate conditions.

3. SCOPE

The IAEA Technical Document is primarily intended to provide the Member States with an overview of radioecological concepts, models and parameters for radioecological assessment of both routine discharges of radionuclides to the environment and accidental releases.

The document is also intended for further updating and facilitating of use of the recently published IAEA documents related to the assessment of the radiological impact of radioactive discharges as described in IAEA Safety Report Series No. 19 Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances to the Environment [5], IAEA Safety Standards Series No. WS-G-2.3 Regulatory Control of Radioactive Discharges to the Environment and other related documents [6]. The document can be also used as background documentation for other relevant activities such as training in radioecology and radiation protection.

4. DATA COLLECTION AND ANALYSIS

International databases of bibliographical references (such as INIS, Scopus, JCR, SpringerLink and Academic Search Premier, INIST, Current Contents, etc.) and some national databases (such as IRSN bibliographical database) were consulted by using relevant

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key words. Such a bibliographical study did not aim at exhaustiveness and was limited to published documents within the international scientific community and, depending on their accessibility, to reports from different scientific institutions. That inventory of existing knowledge was drawn upon with a view to consulting original publications in order to use all the information that they contained, rather than relying on summaries of such information.

During the second step, databases were elaborated, where necessary. These databases associated each value for a given transfer parameter with a number of descriptors. The bibliographical references accepted were also included in the database.

The data have been analysed with the objectives of (i) estimating a geometric mean and/or an arithmetic mean for a given parameter, and (ii) obtaining an indication of the extent of uncertainty about these estimates. The estimation of these values and the extent of uncertainty about every such value have been carried out by applying statistical analysis, when possible.

In the ideal case, if adequate data were available, both a geometric (GM) and an arithmetic means (AM) were derived.

When the number of observations was 2, only the arithmetical mean (AM) was calculated, and the single observation is presented when number of data was equal to 1. The uncertainties assigned to geometric mean were estimated by the geometrical standard deviation (GSD), although the standard deviations (SD) are also calculated as the uncertainty assigned to arithmetic mean. Ranges with minimum and maximum values are also given as well as the number of data (N) and number of references (#ref) used for a value evaluation. In some cases, the expected values are given without a statement of uncertainty or a range because of the limited data available. The recommended values in such cases should be used with caution.

Geometric mean is a type of mean or average, which indicates the central tendency or typical or expected value of a set of numbers:

N N

xi

GM ¹^/

1

) (

∏

= (2)

Geometric standard deviation (GSD) is the exponent of the standard deviation of the natural logarithms of the individual values. GSD can also be calculated based on the expression:

) )) ln(

) (ln(

( exp( ¹

2

N

GM x

GSD

N

∑

i ⁻

=

Arithmetic mean:

∑

⋅

= ^N xi

AM N

1

1 (3)

Standard deviation:

2 / 1 2 1

) ) 1 (

( 1 x AM

SD⁼ N ₋ ^⋅

∑

^N _i ⁻

Thus, standardized tables reporting transfer parameter values are provided where possible giving the following information for each radionuclide: number of entries (N); geometric mean (GM); geometric standard deviation (GSD); arithmetic mean (AM), standard deviation (SD), minimum (MIN) and maximum (MAX) values and number of references from which entries were extracted (# Ref).

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5. SUMMARY OF THE DOCUMENT

The document consists of twentry seven papers unified in nine topics (sections) according to traditional presentation of radioecological data for environmental assessments. Some of radioecological concepts, definitions, units and some important references as well as classifications of soil and plants used in the document are described in the introductory section.

Four papers included into the second section are dedicated to data for, and models of, foliar uptake. The main aspects and processes governing radionuclide mobility in soil including the K_d radionuclide vertical migration concepts and data, are described in the next two papers, composing the section on radionuclide mobility in soil.

Data on root uptake for various environments: temperate, tropical and subtropical, transfer to rice and data for some time dependent contamination scenaries are presented and discussed in the section on root uptake in agricultural ecosystem while the next section is dedicated to radionuclide transfer to animals and animal products. The data on radionuclide transfer in agricultural ecosystems are being completed by the paper on radionuclide transfer to fruits.

Parameters for modelling radionuclide transfer, including data and evaluation of processes governing radionuclide transfer in forest ecosystems (trees, berries, mushrooms, game), Arctic and Alpine environment compose the section on natural and semi-natural ecosystems.

Section on freshwater ecosystems comprises five papers devoted to transport of radionuclides in freshwater ecosystems including contamination routes, physical processes and radionuclide accumulation by freshwater biota. Specific activity models for the relevant radionuclides (³H,

14C, ³⁶Cl), food processing and use of analogue approach for radiological assessments are covered by the section on miscellanius topics. Most papers consist appendexis which provide references used for data evaluation and examples of data evaluation.

REFERENCES

[1] FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS, INTERNATIONAL ATOMIC ENERGY AGENCY, INTERNATIONAL LABOUR ORGANISATION, OECD, NUCLEAR ENERGY AGENCY, PAN AMERICAN HEALTH ORGANIZATION, WORLD HEALTH ORGANIZATION, International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, Safety Series No. 115, IAEA, Vienna (1996).

[2] INTERNATIONAL ATOMIC ENERGY AGENCY, Health and Environmental Aspects of Nuclear Fuel Cycle Facilities, IAEA-TECDOC-918, Vienna (1996).

[3] INTERNATIONAL ATOMIC ENERGY AGENCY, Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environments, Technical Reports Series No.

364, IAEA, Vienna (1994).

[4] INTERNATIONAL ATOMIC ENERGY AGENCY, Generic Models and Parameters for Assessing the Environmental Transfer of Radionuclides from Routine Releases: Exposures of Critical Groups, Safety Series No. 57, IAEA, Vienna (1982).

[5] INTERNATIONAL ATOMIC ENERGY AGENCY, Generic Models for Use in Assessing the Impact of Discharges of Radioactive Substances, IAEA Safety Reports Series No. 19, Vienna (2001).

[6] INTERNATIONAL ATOMIC ENERGY AGENCY, Regulatory Control of Radioactive Discharges to the Environment, IAEA Safety Standards Series No. WS-G-2.3, IAEA, Vienna (2000).

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RADIOECOLOGICAL DEFINITIONS, SOIL, PLANT CLASSIFICATIONS AND REFERENCE ECOLOGICAL DATA FOR RADIOLOGICAL ASSESSMENTS S. FESENKO

International Atomic Energy Agency, Vienna N. SANZHAROVA

Russian Institute of Agricultural Radiology and Agroecology, Obninsk, Russian Federation M. VIDAL

Analytical Chemistry Department–Universitat de Barcelona, Barcelona, Spain H. VANDENHOVE, Y.THIRY

Belgium Nuclear Research Centre (SCK•CEN ), Mol, Belgium E. REED

SENES Oak Ridge Inc., Center for Risk Analysis, Oak Ridge, USA B.J. HOWARD

Centre for Ecology and Hydrology, Lancaster, United Kingdom G. PRÖHL

Helmholtz Zentrum München-Institute of Radiation Protection, Neuherberg, Germany G. ZIBOLD

Hochschule Ravensburg-Weingarten, Germany B. VARGA

Central Agricultural Office, Hungary A. RANTAVAARA

Radiation and Nuclear Safety Authority (STUK), Finland

Abstract

The paper gives an overveiew of radioecological concepts, reference information on plants and soils used in the project. Main classification schemes applied to summarize the data on radionuclide transfer to plants are also described. Generic quantities and units used in the current document are also given. They are mainly defined according to the the ICRU 65 report.

1. DEFINITIONS, QUANTITIES AND UNITS

In 1997, a report committee was initiated and established by the International Commission on Radiation Units and Measurements (ICRU) to prepare a report on statistical aspects and sampling strategies when measuring radionuclides in the environment.

Two reports are being produced: one on the quantities and units used that is already available [1], and the second on statistical aspects and sampling strategies that is at the final stage of preparation.

The first report (ICRU report 65) contained a list of units and quantities frequently used in the field of radioecology, and tried to harmonise the units derived from various different disciplines such as ecology, chemistry, medicine or physics. First symbols, definitions and

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descriptions, their dependencies and a list of previously used symbols are given. In addition, appendices give generic, helpful information for the ‘unexperienced in the specific field’ on soil chemistry, soil classifications, taxonomy of species in common and Latin names in terrestrial and aquatic environments.

The current document mainly follows the recommendations given in the above ICRU report [1]. However, the classification schemes for soils and plants deviate from the recommendations of the ICRU report in a few places, because of specific requirements from the data presentations and their use for radiological assessments. Generic quantities and units used across the entire document are given below (Table 1). As mentioned earlier, they are mainly (with some exceptions discussed below) defined as in the ICRU report 65 [1].

The definitions of specific terms are given in the introductions to the stand-alone papers. Only some of the generic quantities (transfer parameters) that are in wide use are covered by the ICRU report. Those generic parameters that were not defined by the ICRU are also specified in the papers where they are used.

Soil-to-plant transfer factors were defined on a dry weight basis, for both plants and soil to reduce uncertainty. In those cases in which the transfer factor (concentration ratio) values or the plant concentrations, the feed or to berries reported in the literature were expressed relative to fresh weight, the fresh weight/dry weight conversion factors given by Tables 2-4 were applied.

In some estimations given in the document the carcass weighs and meat fractions are in use (Table 5). These fractions were derived by subtraction of the weight of bones and other not edible parts from carcass weights (Table 5).

Thus, all transfer factor values were expressed on a dry weight plant and dry weight soil basis before further analysis and interpretation. It is emphasised that actual fresh weight to dry weight ratios are likely to have varied somewhat around the adopted values, so this is an additional source of uncertainty in the analysis. In some specific situations, fresh weight is used in assessment calculations and in these situations the fresh weight/dry weight conversion factors (see Appendix 1) can be applied to scale the dry weight based values given in this report.

The International Union of Radioecology (IUR) decided, in 1982, to standardize the depth of soil in defining transfer factor values [7, 8]. Instead of the real rooting depth, a standardized depth of soil was adopted. All roots and all activity present in the actual rooting zone are assumed to be present in the standardized zone. For grass, this value is 10 cm and for all other crops (fruit trees included) the value is 20 cm.Transfer factors are commonly used to quantify radionuclide uptake from soil by plants. However, the definition based on the ratio of the activity concentration in plants (Bq kg^-1 dry weight) to that in soil within the layer of a standardized thickness (Bq kg^-1 dry weight), is not appropriate for forests and some other natural and semi-natural ecosystems. The reasons are the multi-layered character of the soils and the high inhomogeneity of distribution of root systems (or mycelia) over the soil profile.

Therefore, aggregated transfer factors (Tag) are used in the current document as an alternative to quantify radionuclide availability to various types of natural or semi-natural vegetation, animals or other products. Tag is defined as the ratio ofthe radionuclide activity concentration in plant or any other natural or semi-natural product (Bq kg^-1 fresh or dry weight, depending on the product) divided by the total deposition on the soil (Bq m^-2). The Tag concept is also used for assessments of radionuclide transfers to game.

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TABLE 1. QUANTITIES AND UNITS USED Symbol used by the ICRU 65 Symbol used in IAEA publications Symbol used in the current document

Name Definition1 Unit1 Specification1 Comments1 . agCagTagTAggregated transfer factor agCis the mass activity density (Bq kg-1 ) in a specified object per unit area activity density, Aa (Bq m-2 ) in the soil.

m2 kg-1 Time, location, pathway, object, wet or dry mass basis, deposition type etc.

Developed to deal with natural and semi- natural transfers from soil to biota. Can be soil to animal, soil to plant etc. It will encompass many processes including food-chain transfers, root uptake, soil adhesion, direct soil ingestion, etc. It may have lower variation in the case of transfers from soil because it may overcome the effects of the differences in soil bulk density between organic and mineral soils. Previous symbols TAG, TF, Tag rCvB, vF, TFvFConcentration ratio rC is the ratio of the activity density of radionuclide in the receptor compartment to that in the donor compartment.

Dimen- sionless or kg kg 1

Depending on compartments specified, radionuclide, receptor and source compartment, wet or dry weight of for each compartment, degree of equilibrium etc.

Most often used to describe plant uptake from the soil, or activity concentrations in aquatic organisms in relation to activity concentrations in water. The intention here is to include such ratios as feed to plant tissue/soil, animal tissue/feed, fish muscle/water etc. The terms bioaccumulation, bioconcentration and biomagnification are related, but are used with very specific connotations that should be carefully specified. The recommended symbol Cr is a change from past usage, but it accomplishes the desire to have a single primary character and to achieve compatibility with other symbols in the ICRU 65 report. Previous symbols CR, TF, Bv, CF, BCG, Br

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TABLE 1. QUANTITIES AND UNITS USED (Cont.) Symbol used by the ICRU 65 Symbol used in IAEA publications Symbol used in the current document

Name Definition1 Unit1 Specification1 Comments1 . frCmF, fF

mF, fF

Feed transfer coefficient

Cfr is the mass or volumetric activity density in the receptor tissue or product of an animal (Bq kg-1 wet mass or Bq L-1 ) divided by the transfer rate (in Bq d-1 ) d kg-1 or d L-1 , where d is the time in days

Radionuclide, animal, specific tissues or animal product; feed type, contamination source; degree of equilibrium between activity density in product and intake rate

The coefficient is used to estimate the activity density in an animal tissue or product that is eaten by humans (i.e. milk, meat, eggs). The tissue or product activity density is assumed to be at steady state with respect to the intake rate. The intake rate in this case refers strictly to intake by ingestion into mouth to be continued. dKdKdK Distribution coefficient The distribution coefficient is the ratio of the mass activity density (Am in Bq kg–1 ) on the specified solid phase (usually on a dry mass basis) to the volumetric activity density (Av in Bq L- 1 ) in the specified liquid phase.

L kg-1 Radionuclide; solid and liquid media; adsorption and desorption basis; laboratory or field conditions; linearity of solid versus liquid concentrations; attainment of equilibrium; ratio of solid to liquid mass, chemical form of radionuclide.

The strict definition is at equilibrium (steady- state equilibrium and reversible processes), but the quantity is often used where complete equilibrium cannot be proven. Additional subscripts may be assigned to clarify the conditions specified, such as whether sorption or desorption is used for the measurement of the Kd. Sorption and desorption Kd values at equilibrium will usually differ. Many methods are used to measure the Kd, and these differences lead to variability and interpretation ambiguities. It is particularly important to describe in detail the method of separating the solid from the solution. If filtration is used, the pore size of the filter should be specified. An operationally defined or fully empirical Kd, for which the two concentrations are measured in field samples, is often preferred to minimise bias caused by the method, but these values often include radionuclides which are not reversibly bound, and for which equilibrium is not necessarily attained. Kd values are sensitive to the composition of the solution (e.g. competing ions, ionic strength, temperature, pH, redox potential), to properties of solids (e.g. clay content and type, particle size, mineralogy) and to the chemical form of the radionuclide. Previous symbols: Rd, CR

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Name Definition1 Unit1 Specification1 Comments1 . αα, fαInterception coefficient The interception coefficient, α, is the ratio of the initial mass activity density on the plant (Am in Bq kg–1 ) per unit areal activity density (Ain Bq m–2 ) on the terrestrial surface (soil plus vegetation).

m2 kg–1 Radionuclide; plant species and part; wet or dry mass basis; washed or unwashed; wet or dry deposition

This quantity is used in the same sense as the Cag, except that is an initial condition, measured before processes such as weathering, leaching and absorption, which alter the activity density on the plant. The term is well defined only for dry deposition. It is often used in the expression for the fraction of the activity density or deposition (Aα) initially intercepted by plant foliage (1–e–αß ), which was described by Chamberlain. The value of the interception coefficient depends on the surface characteristics, meteorological conditions, biomass density, leaf area index, species, plant part, time, etc. Previous symbol: μ K sKKsResuspensio n ratio The resuspension ratio is the ratio of the volumetric activity density, Av, measured in air or water (Bq m–3 ) to the areal activity density. Aα, measured on the soil or sediment surface (Bq m-2 ).

m–1 Receptor compartment; donor compartment (in particular, the depth of the soil or sediment layer assumed to be subject to resuspension); process involved; degree of time-averaging.

The resuspension ratio is intended to represent the transfer from a surface into a volume. It is most often used for the transfer of material from a soil surface into air, but the transfer can be from sediment to water, from water to air, and from other surfaces (e.g. asphalt) to air. The processes are extremely time-dependent due to episodic weather changes, disturbance events, depletion losses, and movement into the soil. The temporal fluctuations can be dampened with time-averaging. When soil or sediment is the donor compartment, it is important to specify the assumed thickness of the compartment, since contamination deeper than a few mm is usually not available for immediate resuspension. In addition to weather and disturbance events, K is extremely sensitive to nature of the surface and to the characteristics of the actual material being resuspended. Previous symbols: RF, RR

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Name Definition1 Unit1 Specification1 Comments1 trftrftrfTranslocation ratio, translocation factor, translocation coefficient

The translocation ratio is the mass activity density (Am in Bq kg–1 ) in one tissue, typically an edible tissue, divided by the mass activity density (Am in Bq kg–1 ) in another tissue of the same plant or crop. It is also can be calculated as the mass activity density in the edible tissue (Bq kg–1 ) in another tissue of the same plant or crop. It is also can be calculated as the mass activity density in the edible tissue (Bq kg–1 ) divided by the activity contained on the mass foliage covering a square metre of land surface (Bq m–2 ) Dimension- less, m2 kg– 1

Radionuclide; kind of plant; specific tissues; type of contamination; contamination history; wet or dry mass.

This quantity is often used to estimate the activity density in an unmeasured tissue from another tissue in the same plant which has been measured. The quantity may be used for fruits, seeds, specific edible vegetables or the bole of trees. It varies with radionuclide and chemical form, time, species, growth stage, nutrition status, etc. Previous symbols: Ti, TF, TLF, TLFα fpfrFrFFood processing retention factor

The food processing retention factor is the ratio of the mass activity density (Am) of a given food item when ready for consumption to the activity density before processing and preparation.

Dimension- less Radionuclide; food; type and conditions of the food processing and preparation.

Examples of food processing and preparation include cheese making, washing, scrubbing, peeling, boiling, baking and frying. Conditions used to determine sample masses before and after processing and preparation must be specified for proper interpretation. This quantity varies according to the radionuclide, the way it is bound to the food, the type of food, and the varied conditions of preparation (e.g. temperature, time, etc.).

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Name Definition1 Unit1 Specification1 Comments1 2/1T2/1T2/1THalf life The half life is (ln2)/λ, where λ is the decay constant (s-1 )

s Radionuclide The half life is specific to each radionuclide and can be visualised as the time required for the activity as a consequence of radioactive decay. af1f1fAbsorbed fraction The absorbed fraction is the fraction of the ingestion or inhalation intake by animal or a human that is transferred to a specified receptor tissue.

Dimension- less Radionuclide; route of intake (pathway), receptor tissue.

This quantity is related to the f1 factor in the metabolic model for human dosimetry, where the receptor tissue is blood, and to blood-tissue transfer fractions. The method of determination is very important; for example, an `apparent` f is computed from information on the whole-body intake and excretion of the radionuclide. A `true`f is measured in a metabolic study that involves injection of a tracer, and allows for the determination of endogenous faecal excretion (i.e. direct transfer from blood to the intestine). The absorbed fraction depends on metabolic factors (e.g. age, lactation state, physiological condition), chemical and physical speciation of the radionuclide, competing ions, gut contents and chemical conditions, etc. Previous symbols: f1, α, Aα, At 1 According to ICRU Report 65 [1].

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TABLE 2. DRY MATTER CONTENTS IN VARIOUS PLANTS, % [2, 3]

Crop Dry matter content (%)

Spring vetch, seeds 86.9

Vegetative mass 24.3

Winter vetch, seeds 87.9

Field pea, seeds 85.1

Garden pea, seeds 83.0

Grass pea vine, seeds 86.4

Soya, seeds 88.6

Lupin yellow, seeds 85.2

Lupin blue, seeds 85.5

Seradella, vegetative mass 22.4

Broadbeans, seeds 88.0

Bean (field, kidney and French), vegetative mass 27.7 Lentil, vegetative mass 24.9

Winter rye, grain 87.0

Wheat, grain 88.0

Oats, grain 86.7

Barley, grain 87.0

Maize (corn), grain 85.2

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TABLE 2. DRY MATTER CONTENTS IN VARIUS PLANTS, % (Cont.)

Sudan grass, seeds 90.0

Sorghum, grain 87.0

Annual ryegrass, vegetative mass 20.0

Millet, grain 88.0

Alfalfa, vegetative mass 26.0 Sickle alfalfa, vegetative mass 33.0 Bastard Lucerne, vegetative mass 23.0 Red clover, vegetative mass 22.0 Ladino clover, vegetative mass 26.0

Sainfoin 23.0 White sweetclover, vegetative mass 22.0

Yellow sweetclover, vegetative mass 22.0 Fussian brome grass, vegetative mass 20.8 Slender wheat grass , vegetative mass 34.0 Couch grass, vegetative mass 37.0 Standard crested grass, vegetative mass 39.0 Timothy grass, vegetative mass 25.5 Meadow fescue, vegetative mass 20.0 Cock’s foot grass, vegetative mass 22.0 Meadow grass, vegetative mass 22.0

Cabbage 12.0 Lettuce 8.0

Leek 11.0

Onion (aboveground part) 11.0

Spinach 8.0 Celery 6.0 Cauliflower 11.0 Kohlrabi 6.0 Tomato 6.0

Cucumber 5.0

Pumpkin (english) 7.5

Vegetable marrow (English) 9.0

Zuchini 5.0

Beetroot (red beet) 16.0

Sugar beet 22.0

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TABLE 2. DRY MATTER CONTENTS IN VARIUS PLANTS, % (Cont.)

Radish 9.0

Carrot 14.0 Potato 21.0

Turnip (Swede) 12.0

Jerusalem artichoke 22.0

Tapioca 38.0 Raspberry 16.0 Water-melon 7.0

TABLE 3. DRY MATTER CONTENTS IN VARIUS FEED, % (www.agriknowledge.co.uk)

Feed Dry matter content (%)

Concentrate feed 0.88

Grass silage 0.26

Pasture 0.20

Grass hay 0.86

Lucerne hay 0.86

Lucerne silage 0.34

Corn silage 0.25

TABLE 4. DRY MATTER CONTENT OF SOME WILD BERRIES, %

English name Latin name N AM SD Max Min Blueberry Vaccinium myrtillus 307 13.2 1.9 21 8.6 Lingonberry Vaccinium vitis-idaea 254 14.1 1.3 18.8 11.3 Cranberry Vaccinium oxycoccus 16 10.8 0.9 12.1 9.3 Bog bilberry Vaccinium uliginosum 6 12.1 1.1 13.5 10.5 Black crowberry Empetrum nigrum 1 7.4 - - - Cloudberry Rubus chamaemorus 26 14.0 1.6 18 9 Wild raspberry Rubus idaeus 21 17.3 1.8 21.9 14.4 Wild strawberry Fragaria vesca 1 15.4 - - -

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TABLE 5. CARCASS WEIGHT AND MEAT FRACTION FOR GAME ANIMALS [4-6]

Species of animal Carcass weight, kg Fraction of meat in carcass weight

Moose, adult 1.9 × 10² 0.80

Moose, calf 8.3 × 10¹ 0.78

White-tailed deer 5.0 × 10¹ 0.78

Fallow deer 3.3 × 10¹ 0.78

Roe deer 1.8 × 10^{1 a} 0.78

Brown hare 2.4 0.90

Arctic hare 1.8 0.90

Capercaillie 1.9 0.90

Black grouse 6.6 × 10^-1 0.90

Hazel grouse 2.4 × 10^-1 0.90

Willow grouse 3.6 × 10^-1 0.90

Partridge 2.4 × 10^-1 0.90

Pheasant 6.9 × 10^-1 0.90

Goose 2.3 0.90

Eider 1.3 0.90

Long-tailed duck 3.8 × 10^-1 0.90

Mallard 6.6 × 10^-1 0.90

Goldeneye 4.5 × 10^-1 0.90

Teal 1.8 × 10^-1 0.90

aRoe deer gains more weight in Northern than in Central Europe.

The concept of Tag is adopted as a reasonable empirical measure to normalize radionuclide accumulation in forest and semi-natural products regardless of variations in the vertical radionuclide distribution and availability in the soil profile, which greatly depends on the site.

Because of the multi-layered character of soils and of great variations in humus thickness in natural and semi-natural ecosystems such as forests, a transfer factor that averages over the total deposit in soil without consideration for the soil layers most exploited by roots, can exhibit a strong time-dependence. Some observations report on the time-dependence of the migration in soil and movement of radionuclides between the various environmental components.

The long-term, time-dependent behaviour of radionuclides is often quantified by reference to the ecological half-life, _T₁^eco_/₂ , which is an integral parameter that lumps all processes except radioactive decay that cause a reduction of activity in a specific medium. The processes involved in determining the value of the ecological half-life are specific to the medium considered, e.g. for the reduction of activity in game, losses of radionuclides from the root layer of the soil, fixation to soil particles and uptake by plants are the most relevant processes.

If radioactive decay – characterized by a physical half-life Tr–is included in the reduction of the content or concentration of a particular radionuclide in a system, then the effective half- life T₁^eff_/₂ is given by:

Tr

T^eff T^eco 1 1 1

2 / 2 1 / 1

+

= (1)