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14 2008 Scientific and Technical Report - IRSN

Radioactivityand the environment1

IRSN - 2008 Scientific and Technical Report 15

1 RADIOACTIVITY and the environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.1 ENVIRHOM’S "ENVIRONMENTAl" THEME: A better understanding of the ecological

consequences of chronic exposure to low-level radionuclides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

newsflashnewsflashnewsflashnewsflashnewsflashnews

1.2 TAkINg INTO ACCOuNT INTERACTIONS between radioactive substances and chemical substances to improve ecological risk assessment in

a multipollution context . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

1.3 THE SAlIFA PRIMEQuAl PROjECT: A study on dry deposition of aerosols

in an urban environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

1.4 CONTRIBuTIONS OF ARTIFICIAl ATMOSPHERIC RADIONuClIDE MONITORINg to the study of transfer processes and the characterization of post-accidental situations . . 37


1.5 "ATMOSPHERIC AEROSOl wASHOuT AND ClEANINg" CAMPAIgN (Puy-de-Dôme):

characterization of atmospheric radioactivity at three sites located at different altitudes . . . 45

1.6 IMPlEMENTATION OF THE ARgOS ExPERIMENTAl PlATFORM for the assessment

and characterization of IRSN environmental radioactivity measurement instruments . . 47

1.7 MAPPINg PRIORITY zONES for radon risk control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49


1.8 MAPPINg lAND uSE AROuND NuClEAR SITES for assessment of radiological and

health impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

1.9 SYMBIOSE: Simulation and modeling of radiological risks to human health

and the environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

1.10 CREATION OF THE TRASSE NATIONAl RESEARCH gROuP as part of the PACEN program (CNRS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

1.11 FOlIAR TRANSFER OF RADIONuClIDES IN THE BIOSPHERE: A study conducted in

Chernobyl in collaboration with Andra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

1.12 MEDIuM PROjECT: Study of sediment mixing and dispersion using particulate

markers in the Seine estuary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

1.13 RADIOACTIVITY IN ORgANISMS of deep-sea hydrothermal sites . . . . . . . . . . . . . . . . . . . . . . . . . . 70

1.14 kEY EVENTS and dates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72


The subjects covered in this report reflect IRSN’s scientific

achievements in three key areas of environmental risk

assessment:

acquiring a better understanding of how chronic exposure to

radionuclides affects ecosystems;

gaining knowledge on the behavior of aerosols dispersed in the

atmosphere and their interaction with soil surfaces;

more accurately predicting the risks of radon concentration in

housing.

Ecological consequences of chronic exposure to radi-onuclidesFor several years now, IRSN has been developing experimental

research programs to improve the scientific bases of the interna-

tional radiation protection system, with particular emphasis on

the ecological and health impact of chronic environmental expo-

sure to radionuclides, within the framework of the ENVIRHOM

research program. A preliminary exploratory research phase com-

pleted in 2007, using "reference" models of chronic exposure of

humans and the environment to uranium, led to the identification

of multiple, sometimes unexpected effects for a broad range of

biological and physiological functions (reproduction, growth,

behavior, etc.).

The article by Adam et al ("ENVIRHOM’s Environmental theme:

A better understanding of the ecological consequences of chron-

ic exposure to low-level radionuclides"), provides an overview of

the results obtained since 2001 in the Environmental part of this

program, focusing on the biological effects observed in various

biological models representative of the aquatic environment

(crustaceans, mollusks, insects, fish) under controlled conditions

of chronic uranium exposure.

This experimental approach is, of course, highly simplistic with

regard to the diversity and complexity of ecosystems and the

multitude of stress factors possibly affecting them. Nevertheless,

contributes to understanding the significant elementary effects

associated with the presence of radionuclides in the environment.

The effects observed at the individual level on fundamental bio-

logical processes provide more accurate information on the "life

history traits" of the species studied, particularly reproductive

capacity and somatic growth, which are essential to population

dynamics. This information is used to determine the concentrations

at which radionuclides have no impact on all or part of the eco-

systems studied, thereby serving as the basis for environmental

risk characterization.

This research has also led to the identification of subcellular

"biomarkers" sensitive to the presence of uranium in the environ-

ment. The biological responses observed are not necessarily

indicative of damage to species or ecosystems, but they can be

used to study the main mechanisms involved during uranium

exposure, in conjunction with the Human Health part of the

ENVIRHOM research program.

Didier CHAMPIONEnvironment and Response

RADIOACTIVITY and the environment


spheric activity, and the importance of wet deposition. The data

obtained is closely representative of the general behavior of

radionuclides dispersed in the atmosphere in the form of par-

ticles, and therefore relevant for developing new atmospheric

radioactivity monitoring networks and for assessing the impact

of accident release over long distances.

In the case of depositions in urban areas, one of the main interests

of the studies conducted by IRSN in collaboration with various

research partners lies in improving the ability to predict the impact

of accidental release in urban environments, particularly with

regard to radiation protection. The results obtained during the

various tracing and measurement campaigns clearly show the

complexity of dry deposition parameters, depending on the type

of deposition surface (with different results obtained for glass

surfaces and façade coatings). These results can be used to quantify

deposition rates for the different surfaces considered, and also to

demonstrate the interest of studying the influence of temperature

and micrometeorology near the deposition surface.

Reviewing the basis of "radon potential" mapsFor several years now, France has developed a radon exposure

control policy including systematic screening of public spaces in

"priority" districts. Thirty-one priority districts were identified on

the basis of bibliographic research campaigns conducted by IPSN

in collaboration with the French Ministry for Health. The objective

was to compile an exhaustive statistical database (over 12,000

measurements of radon concentrations in buildings) sufficiently

reliable to assess the potential exposure of populations through-

out the country. However, the use of these results for the devel-

opment of radon risk prevention strategies has progressively

revealed its limitations, particularly in the case of regions with a

These results generally show the possibility of developing strate-

gies to characterize the ecological status of contaminated eco-

systems. This type of approach is particularly useful for proposing

more relevant ecological risk assessment methods, particularly

through the development of scientifically founded extrapolation

tools. Based on these encouraging results, IRSN is conducting

similar studies with a view to extending current knowledge to

different types of organisms and other radionuclides of interest

(e.g. 241Am, 75Se, or even external exposure to γ radiation from 137Cs).

Behavior of atmospheric aerosolsUnderstanding and predicting the behavior of atmospheric

aerosols (fine radioactive particles suspended in the atmosphere)

and their interaction with soil surfaces has long been one of the

major areas of interest in assessing the environmental impact

of nuclear activities under normal operating conditions, and all

the more so under accident conditions.

Two articles are devoted to this research area: Masson et al,

"Contributions of artificial atmospheric radionuclide monitoring for

the study of transfer processes and the characterization of post-

accident situations", discusses the results of 50 years of radioactiv-

ity monitoring activities throughout France, with special emphasis

on the use of cesium-137, an artificial radionuclide released in the

past during nuclear tests and incidents. Maro et al, "The SaliFa

PRIMEQUAL Project: A study on dry deposition of aerosols in an urban

environment", focuses on dry aerosol deposition in urban areas.

Observations of cesium-137 activity concentration in the atmo-

sphere provide information on various relevant factors such as

the origin of air masses circulating over continental France,

resuspension mechanisms, impact of altitude on specific atmo-


France with a zoning scheme more accurate than the regional

district scale, and with a more objective representation of the

variability in radon exhalation potential at the soil surface. This new

map should provide a more accurate response to the needs of pub-

lic authorities in controlling radon risk.

This report illustrates how IRSN research activities can have an

operational impact on public policy, on the action of social actors

concerned by radon risk control in public spaces, on work places,

and eventually on private dwellings.

contrasted geological context or where the distribution of biblio-

graphic data is not homogeneous.

These past years, at the request of the French nuclear safety author-

ity, IRSN research regarding radon exhalation phenomena has been

used to develop a new approach to map priority zones for radon

risk control. The article by Ielsch et al ("Mapping priority zones for

radon risk control") discusses this research and the new method

proposed, which is currently being implemented by IRSN with a

view to establishing (by late 2009) a new radon potential map of


1. 1

This article presents the approach and ongoing progress of the

Environmental part of the ENVIRHOM research program. Uranium

has been the main target of the research program since it began in

2001. This has led to the development of the necessary tools to

determine biological effects under real or plausible exposure condi-

tions representative of contamination situations potentially encoun-

tered during nuclear fuel cycle activities under normal or accident

operating conditions (from mining activities to waste processing

and storage activities). Uranium was used to contaminate different

ecosystem compartments (water, sediments, soils) under controlled

conditions, and the resulting biological effects were determined for

a limited number of biological models representative of the bio-

logical diversity of the ecosystems (plants, crustaceans, mollusks,

insects, fish).

The most recent results concern the aquatic organisms discussed

in this article. Their interpretation benefits from the knowledge base

acquired since the ENVIRHOM research program began. Other

studies are also in progress with a view to extending this research

to other types of organisms (e.g. complex terrestrial plants) and

other radionuclides of interest, so as to consider different types of

radioactive emissions (e.g. 241Am, 75Se, 3H, or external γ irradiation

with 137Cs).

Christelle ADAM-GUILLERMIN, Jean-Marc BONZOM, Stéphanie BOURRACHOT, Victor DIAS, Rodolphe GILBIN, Adélaïde LEREBOURS, Olivier SIMONRadioecology and Ecotoxicology Laboratory

Jacqueline GARNIER-LAPLACE Study of Radionuclide Behavior in Ecosystems Department

Frédéric ALONZOEnvironmental Modeling Laboratory

Chronic environmental contamination from low-activity radionuclides raises the question of assessing the poten-

tial consequences for humans and ecosystems. This assessment is confronted with insufficient scientific data and

the absence of proven methods that take into account the complexity of the processes involved.

Nevertheless, the future implementation of an environmental radiation protection system consistent with that

currently implemented for chemical substances (European Commission, 2003) requires the determination of

threshold levels above which exposure to radionuclides may induce damage to organisms and populations

constituting ecosystems, with the resulting ecological consequences. The ENVIRHOM research program aims

to address these issues by acquiring new scientific data concerning the effects of chronic radionuclide exposure

and identifying relevant markers through experiments on living organisms (complex vertebrates, fish, inverte-

brates, plants, etc.).

ENVIRHOM’S "ENVIRONMENTAl" THEME: A better understanding of the ecological consequences of chronic exposure to low-level radionuclides

1. 1


High sensitivity of early life stages (studies on Danio rerio)

The effects of radionuclides such as uranium were studied with respect

to the life history traits of several organisms representative of aquat-

ic ecosystems, such as monocellular algae, microcrustaceans (daphnia),

insects (chironomidae) and fish. Danio rerio (zebrafish) is a sort of

aquatic lab rat well suited for toxicological laboratory studies (main-

tainability of controlled conditions, brief life cycle, significant knowl-

edge regarding its physiology, well sequenced genome, etc.). The results

acquired with uranium show a particularly high sensitivity during the

early stages of fish development, from egg to larva [Bourrachot et al,

2008a]. The different stages of embryonic development are not

equally affected by uranium. Pre-eclosion embryos are protected by

the egg envelope (chorion), which prevents most of the metal in the

surrounding environment from entering the organism, whereas the

larval eclosion period is significantly affected by uranium concentra-

tions in water representative of contaminated sites such as those in

the immediate upstream vicinity of certain mining areas (uranium

concentrations of 20 µg per liter and higher), with organisms exhibit-

ing an eclosion delay of up to approximately 40% (Figure 2a).

This eclosion delay is accompanied by a decrease in larval size and

growth rate, and an increase in mortality at higher concentrations.

A decrease in reproductive success is observed in adults exposed

to uranium concentrations of 20 µg/l and higher. The impact on

fecundity (number of eggs laid – Figure 2b) is dramatic, with reduc-

tions of a factor of 2 and 60 for organisms exposed to uranium

concentrations of 20 and 250 µg/l, respectively. In addition, the

From test tubes to ecosystems

Ecotoxicology makes use of different complementary approaches,

ranging from monospecific laboratory biotests to field studies, as

well as laboratory experiments using more or less complex exper-

imental systems. Although in situ studies provide realism and inte-

gration of biological processes, their explanatory and predictive

potential for other situations remains limited due to the complex-

ity of the environment (space-time variables of ecological factors,

adaptation effects, etc.). Studies in controlled environments are

used to examine the responses of organisms to different exposure

conditions representative of potential situations (exposure levels

and pathways, duration, nature and chemical forms of the toxic

element considered, etc.). In a simplified approach, ecotoxicological

studies generally target organisms representative of the different

trophic levels. For example, in the case of continental aquatic

ecosystems, a distinction is made between planktonic species at

the base of the trophic network (algae, microcrustacean consumers),

benthic invertebrates associated with sediments, and fish.

The effects of environmental contaminants are first studied in the

laboratory by measuring responses at the individual level in terms

of fundamental biological processes. For example, in ecotoxicology,

life history traits are considered for all life stages of a given species:

eggs, larvae, juveniles, mature adults, etc. These life history traits

include reproductive capacity (fecundity, reproductive success, etc.)

and somatic growth. The data acquired concerning life history is

integrated into dynamic population models and used to establish

threshold values, i.e. doses or concentrations expected to have no

effect on all or part of an ecosystem. These values are necessary

for environmental risk characterization and management [Garnier-

Laplace et al, 2006 and 2008].

In addition, biological responses can be related to cellular or subcel-

lular alterations of certain specific tissues or organs. The magnitude

of these alterations is an indicator (i.e. biomarker) of exposure level

or effects of contaminants. Biomarkers are used extensively in

ecotoxicology due to their early response capability and their

sensitivity. They also provide a better understanding of toxic action

modes and cellular targets and improve identification of these

phenomena (Figure 1). In order to be useful in environmental risk

characterization, the biomarkers considered must be sensitive to

exposure to environmentally relevant doses, exhibiting quantifiable

dose-response relations and, if possible, reflecting the physiological

status of organisms or even populations.

Tissue/organ

Subcellular/cellular

Individual Population Community

Minutes Hours Days Months Years

Response time

Ecological relevance

Mechanistic basis

Figure 1 Main characteristics of effect indicators as a function of the level of biological organization studied.

Radioactivity in the environment 1. 1


Sensitivity of population dynamics to growth delay and energy budget (studies on Daphnia magna)

Based on data acquired at the individual level, mathematical mod-

els can be used to extrapolate the effects of contaminants on

populations.

This extrapolation is carried out using models of population dynam-

ics such as Leslie’s matrix model (Figure 3a). In this type of model,

the population structure is described as a distribution per age class.

viability of eggs and larvae decreases with the increase in uranium

concentration, since embryos are comparatively more exposed to

uranium through maternal transfer than through direct exposure

to the surrounding environment. These various criteria clearly

indicate the significant sensitivity of early life stages to uranium

exposure, either directly or through parental exposure, with sub-

lethal effects observed at concentrations of 20 µg/l and higher.

They also provide biological response data in terms of incidence on

populations. In a natural environment, the decrease in reproductive

success combined with the increase in larval mortality could have

a significant impact on the survival of certain populations.

Concentration (µg U /L)

HT50

(hpf)

055

60

65

70

75

80

85

90

20 50 100 150 250 500

Number of eggs laid per female

Cyprinid fish (24-hour embryo)

Danio rerio

20 µg U/L 250 µg U/LControl group

600

500

400

300

200

100

0

**

Eggs(future cohort N1)

Cladocera microcrustaceanDaphnia magna

(juvenile)

Number of individuals

Time1 2 3…

i

i

Age

… Max. age

Survival index Si Fecundity index Fi

N1 = ∑ Fi • Ni

Ni+1 = Si • Ni

Ni

Age i(at time t)

Age i +1(at t +1)

Decrease in fecundity

Reproduction time

Increase in mortality

% of effect on life history traits

0% 20% 40% 60% 80%0

2

3

1

Population growth period

Figure 2 Effect of uranium on Danio rerio. a) Mean eclosion time (HT50) expressed in hours of post-fertilization (hpf; average ± confidence interval of 95%; *: statistically different from control group, p < 0.05). b) Number of eggs laid by female after 20 days of exposure to uranium. Source: [Bourrachot et al, 2008a and 2008b].

Figure 3 a) Diagram of mathematical model of population structured by age (Leslie’s matrix model). b) Impact of responses of life history traits on the growth delay of Daphnia magna populations. Source: [Alonzo et al, 2008].

a

a

b

b

1. 1


energy of an organism cannot increase indefinitely, due to food

limitations in the environment and constraints specific to the spe-

cies. Every metabolic cost associated with pollution therefore occurs

at the expense of important processes for population dynamics.

Based on this approach, it is shown that uranium contamination at

concentrations of 25 µg/l and higher leads to critical perturbations

in the nutrition of Daphnia [Zeman et al, 2008]. Also, the slight

increase in energy expenditure (respiration) observed with

Americium-241 has a potentially significant impact on the mass

and survival of individuals in the offspring generation [Alonzo et al,

2006 and 2008].

Tolerance acquisition as an indication of microevolution (studies on Chironomus riparius)

Studies were conducted on the representative benthic invertebrate

Chironomus riparius to determine uranium toxicity at the individual

level for a first generation [Dias et al, 2008]. Subsequently, a com-

parison of the life history traits of populations initially identical but

exposed to different uranium concentrations for eight generations

(0, 32, 64 and 128 µg of uranium per gramme of dry sediment) led

to the identification of microevolutionary phenomena. Changes in

the phenotypic characteristics of populations contaminated for more

than two generations, as compared to control populations, may be

indicative of this type of microevolution [Bell and Collins, 2008]. For

example, as of the first generation, individuals exposed to uranium

exhibit a lower fitness (number of viable and fertile descendants, or

Changes in numbers of individuals in every age class over time are

determined by age-specific survival rates and fecundity rates.

Summing the fecundity of reproductive age-classes yields the num-

ber of individuals in the class of age 1. This simple model is used

to estimate the growth rate (in number of individuals) of a theo-

retical population (Figure 3b).

Due to its short parthenogenetic lifecycle, the zooplanktonic micro-

crustacean Daphnia magna is particularly suited for the acquisition

of data required in this type of model. In this approach, simulations

predicts a delay in population growth, i.e. an increase in the time

required for a population to grow from 10 to 106 individuals in

different conditions of exposure. It is also used to compare the

relative impact on population dynamics of changes in different

criteria measured at the individual level (survival rate, fecundity, age

at first reproduction). Working from the assumption that a popula-

tion is not limited in terms of food or space and that the effects

are the same from one generation to another, it can be shown that

the age at first reproduction has a dominant influence on population

dynamics of an organism such as daphnia (Figure 3b).

However, such models are limited to counting the number of

individuals in a population and does not make it possible to assess

impacts of contaminants on total biomass or biomass structure,

which are relevant ecological indicators. The ecological relevancy

of population dynamics can be improved by integrating physiolog-

ical aspects (food assimilation, energy expenditure, energy reserve,

production) into a dynamic energy budget model [Kooijman, 2000].

This approach is based on the assumption that the acquisition of

Generation

Mean fitness

Diptera insectChironomus riparius

(adult) - 40 1 2 3 4 5 6 7 8

-1

0

1

2

- 3

- 2

32 µg U/g 64 µg U/g 128 µg U/g0 µg U/g

Génération

Fitness moyenne

- 40 1 2 3 4 5 6 7 8

-1

0

1

2

- 3

- 2

32 µg U/g 64 µg U/g 128 µg U/g0 µg U/g

Figure 4 Evolution of mean fitness of Chironomus riparius in the course of eight generations, as a function of contamination (µg U/g of dry sediment). Source: [Dias et al, 2008].



Identification of subcellular biomarkers for a better understanding of the action mechanisms involved

Gene expression profiles

The biological responses observed from the individual level to that

of populations are often the result of various distinct kinetic toxic-

ity mechanisms taking place at the subcellular level and specific to

each target organ. The analysis of gene expression profiles in dif-

ferent organs can constitute a powerful approach to understanding

the diversity of the toxicity mechanisms underlying the effects

observed at other levels of biological organization. This approach

has been used on zebrafish in order to identify the toxic action

mechanisms of uranium in four target organs: gills, skeletal tissue,

liver and brain.

The expression level of a set of 20 genes involved in cellular toxic-

ity mechanisms (Table 1) has been measured by RT-PCR (Reverse

Transcription-Polymerase Chain Reaction) in male zebrafish exposed

to approximately 20 and 100 µg of depleted uranium per liter. The

gene expression profiles show that at concentrations of 20 µg/l and

higher, uranium exposure induces a change in the expression of

certain genes involved in inflammatory and oxidative response.

Genes involved in apoptosis (particularly in skeletal tissue), mito-

chondrial metabolism and DNA repair are also affected. In the brain,

the vchat and gls1 genes are also induced, which indicates a neural

response affecting glutamate synthesis and the cholinergic system,

consistent with the previously reported effects of uranium on

variations in acetylcholinesterase activity [Barillet et al, 2007).

Genetic responses vary depending on the organ considered. In the

gills, despite the accumulation of high concentrations of uranium,

product of survival and fecundity rates) than non-exposed individu-

als (Figure 4). However, this decrease in fitness disappears gradually

from one generation to the next for all uranium concentrations, and

by the eighth generation exposed individuals exhibit the same size

as non-exposed individuals. Is this a genetic selection in response to

uranium exposure? To answer this question, "common garden"

experiments were conducted [Falconer and Mackay, 1996], consisting

of transferring all test populations to the same non-contaminated

environment and comparing their performance data. The results

obtained have revealed a phenotypic divergence suggesting a genet-

ic divergence between the control populations and those previously

exposed to uranium. However, other measurements taken in the

course of this experiment seem to show that, despite the adaptation

of exposed populations to uranium, the metabolic cost of acquiring

this tolerance makes them more vulnerable to a new environment,

even if it is identical to their original environment.

When populations previously exposed to significant uranium con-

tamination (128 µg of uranium per gramme of dry sediment) are

placed once again in a non-contaminated environment, they exhib-

it a lower reproductive success rate than the control populations.

This result suggests that rapid and frequent environmental changes,

as compared to the characteristic duration of a generation (or life-

cycle), may have an environmental impact on populations specialized

for a specific environment, and that these populations could tend to

disappear. Although these populations are clearly capable of adapt-

ing to an environment contaminated with uranium, the metabolic

cost of this tolerance acquisition can make them more vulnerable to

a new environment (e.g. lower reproductive success rate than control

populations). This example illustrates the complexity of the eco-

logical processes involved and the multitude of indirect effects to be

considered.

Table 1 Comparison of gene expression alterations in four target organs of uranium for zebrafish exposed to 20 or 100 µg/l [Lerebours et al, 2008].

Cellular processes Brain Skeletal tissue Liver Gills

Detoxification cytp450 tap, cytp450 tap, cytp450 –

Stress oxydantgpx, gst, cat

catgpx, gst, cat, sod(Cu/Zn),

sod(Mn)gpx, sod(Mn)

Apoptose – bax bax –

DNA repair gadd – gadd rad51(1)

Mitochondrial metabolism – coxI coxI coxl(1)

Inflammation il1 il1 il1 –

Neural response vchat, cd11b, gls1 Undetermined Undetermined Undetermined

(1) Alteration observed only at 100 µg U/l.

1. 1


Certain types of damage may be correctly repaired with normal

pursuit of the cell cycle, other types may be non-repairable,

resulting in the elimination of cells affected by apoptosis, and

others may be incorrectly repaired. In the latter case, irreversible

effects may occur, such as mutations, carcinogenesis and terato-

genesis.

In vitro studies

Fish primary cell cultures for in vitro studies have been developed

to establish rapid and sensitive tests for discerning the genotoxic

potential of uranium and thereby identify the most sensitive in vivo

exposure scenarios. The alkaline comet test has been privileged for

the detection of genotoxic events. This test detects single and

double-stranded DNA breaks, as well as alkali-labile sites. It requires

the dissociation of tissues in order to isolate cells without altering

their DNA.

Among the various possible cell types, germ cells and hepatic cells

have been selected, since they are particularly useful in evaluating

genotoxicity. An alteration of the genetic material of gametes can

compromise an organism’s ability to produce viable descendants,

and can modify the genetic constitution of subsequent generations

by introducing more or less deleterious mutations, thereby causing

a severe impact on population dynamics. The liver plays a central

role in the general metabolism of an organism, and also in the

detoxification and transformation of toxic molecules penetrating

the organism.

a very limited number of genes is induced at the higher concentra-

tion level, and very moderately so (maximum induction factor

of 7), suggesting a low sensitivity of this organ to uranium exposure.

In the liver, where high concentrations of uranium also accumulate,

genetic responses (induction or repression) are observed for a large

number of genes (maximum repression factor of 100), mainly at

the lower exposure concentration (20 µg/l). The absence or decrease

in number of repressed or overexpressed genes during exposure to

a high concentration of uranium could indicate that the organ’s

defense capacity has been exceeded, which can be corroborated

with the liver histopathologies observed by other researchers [Cooley

et al, 2000]. Finally, in the brain and skeletal tissue, where the

accumulation of uranium is approximately 10 times lower, numer-

ous genes respond precociously and with a more marked intensity

at the lower concentration level, clearly indicating the sensitivity

of these organs to uranium exposure, in conjunction with the

potential neurological effects of this element.

DNA alterations and effects at the individual level

Exposure to radionuclides can directly modify the structure and

function of the main biological macromolecules: lipids, sugars,

proteins, and nucleic acids. It is generally acknowledged that DNA

is the target molecule of radiation-induced damage and associ-

ated biological effects. The impact of the various structural DNA

modifications induced by ionizing radiation can be more or less

severe, depending on how they are repaired by cellular defense

mechanisms.

00 1 10 100 750

10

20

30

40

DNA in comet tail (%)


Depleted uranium (µM)Dose rate (mGy/day)

00 1 10 100

10

20

40

50

30

* *

**

**

** ***

Hepatocytes Gametes Hepatocytes Gametes

DNA labelled with ethidium bromideBottom: intact DNATop: damaged DNA

Figure 5 Level of DNA damage (percentage of DNA in comet tail) in male gametes and hepatocytes exposed for 24 hours to (a) dose rates (external gamma radiation, 137Cs) and (b) concentrations of depleted uranium. Average ± standard error (n = 5; *: p < 0.05, **: p < 0.01, ***: p < 0.001). [Giraudo, 2006].

a b



adults were directly exposed for 20 days to depleted uranium in

concentrations of 20 and 250 µg/l [Bourrachot et al, 2008b]. In

the case of individuals exposed to a uranium concentration of

250 µg/l, a decrease in reproductive performance was observed

(Figure 2b), associated with a significant increase in the quantity

of DNA damage in male and female germ cells (Figure 6). The

uranium concentrations in tissue (5 to 15 mg of uranium per kg

of gonad, calculated based on a fresh-to-dry-weight ratio of five)

are of the same order of magnitude as the concentrations used in

vitro (2.4 to 24 mg/l in the culture environment), which confirms

that cell cultures may be used as a screening tool.

This consistency between the data obtained from in vitro and in

vivo studies, combined with the identification of target organs of

uranium accumulation exhibiting high cell sensitivity, implies that

the effects observed at the molecular level may be linked to those

observed at the individual level. Nevertheless, this type of correlation

does not necessarily imply a direct cause and effect relationship,

and may merely indicate common toxic action mechanisms.

Conclusion

The approach adopted with uranium to identify individual

responses and their impact on populations, in conjunction with

action mechanisms identified at the subcellular level, shows how

current knowledge of the ecological consequences of chronic

exposure to low concentrations of radionuclides could be gradu-

ally improved, and which tools could be used in the future for

determining the ecological status of a contaminated ecosystem.

This approach is particularly useful for developing a relevant

ecological risk assessment method, particularly through the use

of scientifically founded extrapolation tools (e.g. extrapolation of

effects from individuals to populations using mathematical mod-

els). These developments require further experimental studies to

select ecologically relevant criteria and gradually replace current

extrapolation rules with adequate knowledge.

Effect biomarkers can also be used to further knowledge on the

predominant accumulation and effect targets in organisms (in

conjunction with the Human Health part of the ENVIRHOM

research program) by using tools based on the observation of

early response, useful for monitoring ecosystem contamination.

The sensitivity of the two cell types considered (hepatocytes and

male gametes) has been compared for exposure to external gamma

radiation or depleted uranium (Figure 5). In the case of exposure

to external gamma radiation, a significant increase in the number

of DNA breaks is observed in gametes at 1 mGy/day, whereas

hepatic DNA alterations only occur at 750 mGy/day. Likewise, in

the case of exposure to depleted uranium, a significant increase in

DNA damage is observed in male gametes at the second uranium

concentration level (2.4 mg/l), whereas no significant trend is

observed in hepatocytes. These results show that the extent of DNA

damage is a function of the cell type considered, characterized by

the repair capacity of the DNA and a specific cellular renewal rate.

Since spermatozoa lack efficient DNA repair systems, they maintain

DNA integrity with difficulty and are therefore more sensitive to

the presence of genotoxic agents in the environment than hepa-

tocytes.

In vivo studies

The high sensitivity of germ cells observed in vitro leads to the

consideration of possible effects on reproductive parameters. An

in vivo study was therefore conducted to determine the link between

DNA alterations in germs cells and effects on fecundity. Danio rerio


Spermatozoa (light microscope)

250 µg U/L20 µg U/L0

Control

5

10

20

25

30

35

40

15*

***

Female gametes Male gametes

x 200

Figure 6 DNA damage measured by comet tests on male and female gonad cells. Average ± standard deviation (n = 3; *: p < 0.05 and ***: p < 0.001). Source: [Bourrachot et al, 2008].

1. 1


References

F. Alonzo, R. Gilbin, S. Bourrachot, M. Floriani, M. Morello, J. Garnier-Laplace (2006). Effects of chronic internal alpha irradiation on physiology, growth and reproductive success of Daphnia magna. Aquat Toxicol 80(3), 228-236.

F. Alonzo, T. Hertel-Aas, M. Gilek, R. Gilbin, D.H. Oughton, J. Garnier-Laplace (2008). Modelling the propagation of effects of chronic exposure to ionising radiation from individuals to populations. J Environ Radioactiv, 99, 1464-1473.

S. Barillet, C. Adam, O. Palluel, A. Devaux (2007). Bioaccumulation, oxidative stress and neurotoxicity in Danio rerio exposed to different isotopic compositions of uranium. Environ Toxicol Chem 26(3), 497-505.

G. Bell, S. Collins (2008). Adaptation, extinction and global change. Evol Appl 1, 3-16.

S. Bourrachot, O. Simon, R. Gilbin (2008a). The effects of waterborne uranium on the hatching success, development and survival of early life stages of zebrafish (Danio rerio). Aquat Toxicol, publication in progress.

S. Bourrachot, L. Aubergat, O. Simon, R. Gilbin (2008b). Effects of uranium on reproduction of zebrafish: relationships between biomarkers of exposure and toxicity. Congrès SETAC Europe, Varsovie, 25-29 mai.

H.M. Cooley, R.E Evans, J.F. Klaverkamp (2000). Toxicology of dietary uranium in lake whitefish (Coregonus clupeaformis). Aquat Tox 48, 495-515.

V. Dias, C. Vasseur, J.M. Bonzom (2008). Exposure of Chironomus riparius larvae to uranium: effects on survival, development time, growth, and mouthpart deformities. Chemosphere 71(3), 574-581.

European Commission (2003). Technical Guidance Document. Dir. 93/67/EEC and Reg. EC 1488/94, Dir. 98/8/EC.

D.S. Falconer. T.F.C. Mackay (1996). Introduction to Quantitative Genetics, Ed 4. Longmans Green, Harlow, Essex, UK.

J. Garnier-Laplace , C. Della-Vedova, R. Gilbin, D. Copplestone, J. Hingston, P. Ciffroy (2006). First derivation of predicted-no-effect values for freshwater and terrestrial ecosystems exposed to radioactive substances. Environ Sci Technol 40, 6498-6505.

J. Garnier-Laplace, D. Copplestone, R. Gilbin, F. Alonzo, P. Ciffroy, M. Gilek, A. Agüero, M. Björk, D.H. Oughton, A. Jaworska, C.M. Larsson, J.L. Hingston (2008). Issues and practices in the use of effects data from FREDERICA in the ERICA Integrated Approach. J Environ Radioactiv, 99, 1474-1483.

M. Giraudo (2006). Développement et optimisation du test des comètes sur cellules primaires isolées de poisson zèbre (Danio rerio) : application à l’étude des effets de l’uranium. Stage de Master II, Master Recherche bioinformatique, biochimie structurale et génomique, université de Provence – Aix-Marseille I.

S.A.L.M. Kooijman (2000). Dynamic energy and mass budgets in biological systems. University Press, Cambridge, 424 p.

A. Lerebours, P. Gonzales, C. Adam, V. Camilleri, J.-P. Bourdineaud, C. Garnier-Laplace (2008). Comparative analysis of gene expression in brain, liver, skeletal muscles and gills of the zebrafish (Danio rerio) exposed to environmentally relevant waterborne uranium concentrations. Submitted to Environ Toxicol Chem.

F.A. Zeman, R. Gilbin, F. Alonzo, C. Lecomte-Pradines, J. Garnier-Laplace, C. Aliaume (2008). Effects of waterborne uranium on survival, growth, reproduction and physiological processes of the freshwater cladoceran Daphnia magna. Aquat Toxicol 86(3), 370-378.

1.2

newsflashnewsflashnewsflashnewsflashnewsflashnewsflash


Rodolphe GILBIN, Catherine LECOMTE-PRADINES,

Céline RÉTY, Florence ZEMANRadioecology and Ecotoxicology Laboratory

(1) Technical Guidance Document on Risk Assessment – http://ecb.jrc.it/Technical-Guidance-Document/

(2) ERICA integrated assessment tool – http://www.erica-project.org/

In the event of chronic exposure of a con-

tinental aquatic ecosystem to low concentra-

tions of contaminants, risk assessments

currently performed often result in the iden-

tification of several potentially hazardous

contaminants (chemical or radioactive sub-

stances). These contaminants may act in a

synergic or antagonistic manner, and their

effects add up with those of natural variables

(temperature, luminosity, eutrophication,

etc.). Ecological risk assessments need to take

these interactions into account, whether to

determine the exposure of living organisms

or to assess potential effects. However, the

operational assessment methods currently

recommended by the European Agency for

Chemical Substances (described in the

Technical Guidance Document on Risk

Assessment(1)) and the tools recently pro-

posed for assessing the ecological risks asso-

ciated with radionuclides(2) do not provide

relevant models of multistress contexts, since

mixture scenarios are not considered.

The project considered here is being

conducted in the Radioecology and

Ecotoxicology Laboratory in conjunction

with the Environmental part of the

ENVIRHOM research program. It began in

2005 with a first study on daphnia, an

aquatic microcrustacean (thesis defended

by F. Zeman in October 2008). This study

has led to the establishment of a method-

ological framework for the identification

of interactions in a binary mixture of ura-

nium and selenium.

The general approach is illustrated in

Figure 1:

exposure studies are performed by evalu-

ating the potential physical and chemical

interactions between contaminants and

their impact in terms of exposure of bio-

logical ecosystem components (exposure

of habitats, bioavailability);

effect studies are conducted by establish-

ing dose-effect relationships to determine

the effect levels for each substance consid-

ered individually, and by applying modeling

methods for mixture effects (i.e. concentra-

tion addition; independent action);

risk characterization studies are con-

ducted by integrating interactions at the

exposure and effect level.

The results obtained have shown that a

complete test design (i.e. testing each

binary mixture in variable proportions) is

indispensable for identifying a genuine

interaction between the different sub-

stances. As a result, an antagonistic effect

of selenium on uranium toxicity was iden-

tified. Further research is being conducted

within the framework of a joint project

between IRSN and EDF (GGP-Environment

project) devoted to improving prospective

TAkiNG iNTo ACCouNT iNTERACTioNS between radioactive substances and chemical substances to improve ecological risk assessment in a multipollution context



or retrospective assessments of potential

risks for continental aquatic ecosystems

(large rivers), associated with chronic, spo-

radic, or diffuse release from nuclear power

plants (NPP) under normal or incident oper-

ating conditions, taking into account the

specific characteristics of their catchment

basins. This research considers a number of

chemical substances (metals, organic

micropollutants) and radioactive substanc-

es (beta and gamma radiation emitters),

particularly as a function of natural stress

parameters (eutrophication, temperature).

Experimental studies (thesis by C. Réty,

2007-2009) have been devoted to a lim-

ited number of substances representative

of routine releases from NPP and charac-

teristic of specific exposure types (e.g. cop-

per, tritium), and to a phytoplanktonic

organism (growth inhibition in a monocel-

lular green alga, photosynthesis and oxida-

tion stress). The effect of gamma radiation

has also been studied on this organism.

As a supplement to the research con-

ducted within the framework of the

ECOSENSOR program, coordinated by the

National Institute of Universe Sciences

(CNRS-INSU) in collaboration with the

Hydrosciences Laboratory of the University

of Montpellier and the Macromolecular

Biochemistry Research Center (CNRS UMR

5237, Montpellier), the project considered

here aims to study the effects of mixtures

of contaminants with different action

mechanisms (cadmium, nonylphenol,

gamma radiation emitters) using wild-type

and mutant nematode C elegans as biosen-

sors.

The final objective is to provide an eco-

logical risk indicator based on comparison

with environmental monitoring data, so as

to validate new interaction models and

define their scope of application.

Total concentration

Bioavailable concentration

Internal concentration

Toxic effect

Speciation

Total concentration

Bioavailable concentration

Speciation

Substance 1 Toxico-kinetic

Substance 2

EXPOSURE

Internal concentration

Toxic effect

Toxico-kinetic

Toxico-dynamic

Toxico-dynamic

Interaction Interaction Interaction ? ? ?

Figure 1 Schematic representation of the different possible levels of interaction between two substances (thesis by F. Zeman, 2008).


From 2005 to 2007, IRSN teams participated in the SaliFa-

PRIMEQUAL research program(1) [Sacré et al, 2006], whose general

objective was to acquire a better understanding of the physical

mechanisms responsible for the soiling of building façades. Various

teams collaborated on this project. The National Center for Building

Science and Technology (CSTB), the Interprofessional Research

Center for Aerothermochemistry (Coria) and the Central Research

Institute in Nantes (ECN) participated in building analysis, micro-

meteorological measurement and digital simulation activities.

The dry deposition study consisted of short-term and long-term

experiments conducted by IRSN in the city of Nantes.

The short-term experiments were used to study dry deposition

processes as a function of different parameters such as substrate

temperature or atmospheric turbulence. Calibrated fluorescein

aerosols were artificially generated to quantify dry deposition.

The long-term experiments consisted of conducting a global anal-

ysis of deposition phenomena using beryllium-7 (7Be) as a tracer

of dry deposition. This radionuclide is naturally present in the air

as an aerosol.

Test specimens were selected by CSTB and consisted of two types

of glass (non-treated glass and titanium oxide-coated glass requir-

ing reduced maintenance and less frequent cleaning) and three

types of façade coatings with a surface roughness of 2, 3 and

5 mm.

The different teams involved in the project participated at different

stages. The CSTB team selected and prepared the glass and coating

Denis MARO, Olivier CONNAN, Didier HÉBERT, Marianne ROZETRadioecology Laboratory of Cherbourg-Octeville

Urban areas contain over 70% of the population in most developed countries. The potential radiological impact

of contamination in urban environments is therefore an issue of current interest for the management of post-

accident situations. In order to consider the hypothetical case of an accident or act of terrorism involving

radionuclides in gaseous or aerosol form in an urban environment, it is important to have a good understanding

of radionuclide transfer processes throughout the urban ecosystem so as to predict their impact on populations.

For several years now, IRSN teams have been studying the dry deposition of aerosols on the surfaces of build-

ings. To date, the dry deposition of aerosols remains a research area seldom explored at the international level.

This research requires an in situ experimental approach to take into account specific local characteristics (turbu-

lence, substrates, etc.) [Maro et al, 2004].

THE SAlIFA PRIMEQuAl PROjECT: A study on dry deposition of aerosols in an urban environment

1. 3

(1) Inter-organism research program for better local air quality, coordinated by the French Ministry for Ecology and Sustainable Development and the French Agency for Environmental and Energy Management (Ademe).


1. 3

integrated over the entire plume passage time at the observation

time, and the total quantity of SF6 emitted. SF

6 was more appropri-

ate for spot measurements than fluorescein, when it was necessary

to compensate for the lack of systematic measurements of fluo-

rescein concentration in the air (only two measurements per

experiment) and to check substrate concentration homogeneity

(Figure 2).

Micrometeorological measurements were also performed at the

test site, near the aerosol generation system and near the sub-

strates.

This method (Figure 1) was applied during two field test campaigns.

The SaliFa 1 and 2 campaigns were conducted from June 28 to 30,

2005, in downtown Nantes (Medical school conference center), and

from June 6 to 8, 2006, at ECN (Figures 3 and 4).

Emission of fluorescein aerosols and SF6 tracer gas

Aerosols were emitted in the air using a pneumatic fluorescein

generator. The various modules for air spraying, dilution and drying

were adjusted to generate particles with a mean mass diameter of

0.2 µm (dry aerosol). This mean mass diameter was chosen because

it corresponds to that of the accumulation mode of particles in an

urban environment [Boulaud and Renoux, 1998].

The system was calibrated [AFNOR NFX 44-011, 1972] to obtain

particles with a mean mass diameter of 0.24 µm (standard geometric

deviation of 1.7). Fluorescein aerosols were generated for a period

of 60 minutes and the distance between the fluorescein emission

point and the various substrates placed in the emission stream was

15 m.

specimens tested and ensured on-site management of the long-term

experimental campaign (Nantes medical school conference center),

the ECN team performed meteorological measurements and

numerical simulations, the Coria team performed turbulent flux

measurements near substrate walls, and the IRSN team measured

the dry deposition rates of aerosols during the short-term and

long-term experimental campaigns.

Experimental equipment and methods

Short-term experimental campaigns: measuring aerosol

dry deposition rates using a dry deposition tracer

Principle

The method developed by the Radioecology Laboratory of Cherbourg-

Octeville (LRC) can be used to determine the dry deposition rates

of aerosols by emitting fluorescein (uranin) in dry aerosol form

toward an experimental setup comprising atmospheric aerosol

sampling systems and the various substrates studied (Figure 1).

After emission, samples were collected for subsequent measurement

by spectrofluorometry.

The deposition rate (m.s-1) was calculated as the ratio between the

dry deposition flux on the substrate (kg.m-2.s-1) and the atmo-

spheric concentration at the substrate level (kg.m-3).

A tracer gas (sulfur hexafluoride, SF6) was emitted simultaneously

with the fluorescein so as to determine the atmospheric transfer

coefficient (ATC, i.e. time-integrated concentration at a given point,

normalized to the total quantity released) and thereby obtain the

atmospheric aerosol concentration at the level of each substrate.

The ATC was calculated as the ratio between the SF6 concentration

Emission (fluorescein aerosols)0.2 µm - 60 min

Emission point

Emission (SF6 tracer)

Wind direction

Distance – 15 m

Substrates

Sampling on filters

(HVS)

Air

Meteorology, micrometeorology and granulometry

of atmospheric aerosols

SF6 concentration measurements on five types of substrate

Recovery

Fluorescein extraction

Fluorescein measurements (air and substrate)

Dry deposition rate(ratio between dry deposition

flux and atmospheric concentration)

Figure 1 Diagram of experimental setup.

Radioactivity in the environment


1. 3

modules to collect atmospheric aerosol samples. After each emis-

sion, the various test samples (air filters and test tubes) were

protected with aluminum foil and stored for subsequent analysis.

Air samples for SF6 analysis were taken in 1-liter gas bags (TedlarR)

throughout the duration of fluorescein emission, using a specific

technique developed by IRSN (DIAPEG). Samples were taken at the

four corners and at the center of the test tube holder (Figure 2).

Measurement of concentration of fluorescein aerosols and

SF6 tracer gas

To measure the concentration of fluorescein aerosols in the air, the

filters were switched off and immersed in an aqueous ammonia

solution at pH 9, with mechanical agitation for 20 minutes. To

measure the concentration of aerosols deposited on the substrates,

SF6 was emitted as a tracer gas simultaneously with the fluores-

cein aerosols (30 mg.h-1). This gas is not naturally present in the

atmosphere. The system used consists of an SF6 canister (Messer)

connected to a mass flow meter (Sierra 820). The gas was emitted

through the aerosol spray tube (SF6 emission rate = 0.4 g.s-1).

Sampling of fluorescein aerosols and SF6 tracer gas

Fluorescein aerosols were sampled from the emission stream in

order to measure the concentration in the air and on the glass and

façade coating substrates. Atmospheric aerosols were collected on

Whatman 40 filters (Ashless 40-1440917) via two high volume

samplers (HVS) with a flow rate of 30 m3.h-1.

During fluorescein emission, three test tubes of each type were

placed on a holder in the fluorescein plume flow near the HVS

Vertical façade

HVS(aerosol sampling)

HVS(aerosol sampling)

Coating (3 mm) Coating (5 mm)Non-treated

glass

Low-maintenance

glassCoating (2 mm)


glass

Low-maintenance

glassCoating (2 mm)


glass

Low-maintenance

glassCoating (2 mm)

DIAPEG 1(air sampling)





Figure 2 Basic diagram of position of substrates, aerosol sampling systems (HVS) and air sampling systems (DIAPEG).

Figure 3 Short-term experimental campaign: position of substrates and sampling systems (Nantes medical conference center).

Figure 4 Short-term experimental campaign: position of substrates and sampling systems (ECN).

HVS

Test specimens (glass, coatings)

Meteorological station

Release (fluorescein, SF

6)

DiAPEG

HVSTest specimens (glass, coatings)

ultrasonic anemometers

Release (fluorescein, SF

6)

DiAPEG


spectrometry in a laboratory with low background noise (French

navy underground laboratory, EAMEA/GEA). The 7Be activity depos-

ited on each specimen was measured and compared with the mean

atmospheric activity of 7Be at the moment of exposure, so as to

determine the deposition rate. The 7Be activity in the atmosphere

was not measured in Nantes. Values measured by the Metrology

Library (IRSN Orsay) in different sites such as Alençon and Bordeaux

were used.

Results and discussion

Short-term campaigns

Measurements were performed under low wind conditions, i.e.

1 to 2.2 m.s-1. Air friction against the soil (U*) ranged from 0.1 to

0.6 m.s-1. The deposition rates obtained during the experimental

campaigns in June 2005 (SaliFa 1) and June 2006 (SaliFa 2) are

summarized in Table 1. Dry deposition rates ranged from 1.1.10-5

to 3.0.10-5 m.s-1 for glass specimens and from 4.2.10-5 to 1.2.10-4

m.s-1 for façade coating specimens.

The dry deposition rates obtained during the SaliFa 1 and 2 test

campaigns were, respectively, 3.0.10-5 m.s-1 and 1.5.10-5 m.s-1 for

non-treated glass, and 2.8 .10-5 and 1.1.10-5 m.s-1 for low-mainte-

nance glass. Taking into account the associated uncertainties

(< 58%), no significant differences were observed between the

two types of glass. The deposition rates were systematically

higher for both types of glass during the SaliFa 1 campaign. The

higher air temperatures and insolation values during the SaliFa 2

campaign could have had an influence, via the thermophoresis

effect.

During the SaliFa 2 campaign, the air temperature and the surface

temperatures of the different specimens were measured to take

this influence into account. In the case of glass, the deposition rates

the glass specimens and façade coating specimens were washed

with an ammonia solution at pH 9. The washing solutions were

then filtered at 0.2 µm prior to measurement by spectrofluorometry.

Fluorescein concentration measurements were performed using a

UV spectrofluorometer (Horiba Fluoromax-3). The excitation wave-

length was set to 490 nm and emission was measured at

512 nm.

The SF6 content in the air samples was measured by gas phase

chromatography (AUTOTRAC, Lagus Applied Technology Inc.).

Acquisition of micrometeorological data

Micrometeorological data (particularly air friction against wall and

soil) was obtained using ultrasonic anemometers (Young 81000,

20 Hz) placed at different points throughout the test site. In addi-

tion to this setup, a meteorological station (PULSONIC) was placed

between the fluorescein generator and the test tube holder to

measure wind speed and direction, relative humidity, temperature

and atmospheric pressure. Substrate wall temperature was also

measured during the SaliFa 2 campaign, using an FX 410 infrared

thermometer (Jules Richard Instruments).

Long-term experimental campaign: use of 7Be naturally

present in the atmosphere as a dry deposition tracer

In addition to the short-term experimental campaigns, a long-term

campaign was conducted to determine the soiling impact of aero-

sol deposition and to quantify the dry deposition. The same types

of urban substrates as those used during the short-term campaigns

were installed on a wall in downtown Nantes from April 2005 to

August 2006 (Figure 5). These substrates were placed on the north-

east façade of the Medical school conference center, therefore

protected from heavy rain. Samples were taken periodically after

different periods of exposure to urban pollution and at different

times of the year.

The method implemented consisted of measuring the 7Be deposi-

tion on the glass specimens and façade coating specimens. 7Be is

a radionuclide with a half-life of 53.2 days, naturally present in the

atmosphere, which adheres to atmospheric aerosols with a particle

size in the order of 0.4 µm. 7Be activity levels in the atmosphere

depend on air mass exchanges between the troposphere and strato-

sphere, and on the dry and wet deposition of aerosols. This radio-

nuclide can therefore be used as a tracer of deposition. Once they

were removed from the exposure wall, specimens were treated as

quickly as possible, since the half-life of 7Be is quite short. The

specimens removed from the wall were rinsed with acidified water.

The radioactivity of the wash water was then measured by gamma

1. 3

Figure 5 Long-term experimental campaign: position of substrates on the northeast façade of the Nantes medical conference center.



similar differences in the deposition rates of coating specimens and

glass specimens.

At this stage, it is difficult to explain these differences, but air

temperatures and substrate surface temperatures probably play a

role. Unfortunately, the temperature of the substrate walls was not

measured during the SaliFa 1 campaign. The results obtained during

the SaliFa 2 campaign indicated that this was a significant param-

eter. In the case of micrometeorological parameters such as rough-

ness length and wall and soil friction, the differences between the

two campaigns appeared to be minimal, and the micrometeoro-

logical conditions during the two campaigns can be considered as

similar. No relationship was demonstrated between variations in

deposition rate and with these micrometeorological parameters.

Long-term campaign

Three series of measurements were performed, corresponding to

test specimens removed from the exposure wall in December 2005

(after 8 months of exposure time), April 2006 (after 12 months of

were inversely proportional to the surface temperature of the

specimens (Figure 6), and they decreased as the temperature dif-

ference between the air and substrate wall increased (Figure 7).

The average dry deposition rates obtained for the different façade

coatings are listed in Table 1. They range between 4.2.10-5 and

1.2 10-4 m.s-1, with no significant differences between coatings with

different roughness values. The temperature difference between

the air and the coating specimens was much lower than for the

glass specimens (3°K and 8°K, respectively). As a result, no correla-

tion was observed with the deposition rate. As in the case of the

glass specimens, the deposition rates obtained during the SaliFa 1

campaign were slightly higher (by a factor of approximately 2).

It should also be noted that the difference between the deposition

rates for glass specimens and coating specimens was similar during

each campaign. The deposition rates for coating specimens were

higher than those for glass specimens by a factor of 3.8 during the

SaliFa 1 campaign and by a factor of 3.5 during the SaliFa 2 campaign.

The results for both campaigns were therefore consistent, showing

1. 3

Emission number

00 1 2 3 4 5 6

Deposition rate (m.s-1) 1/T° glass (K-1)

2.5.10-5

2.10.10-5

1.5.10-5

1.10.10-5

5.10-6

Low-maintenance glass

Inverse of substrate temperature

Non-treated glass

3.5.10-3

3.4.10-3

3.3.10-3

3.2.10-3

Deposition rate (m.s-1)

T° glass - T° air (°K)1 2 3 4 5 6 7 8 9


Non-treated glass

2.5.10-5

2.10-5

1.5.10-5

1.10-5

5.10-6

0

Figure 6 Variations in dry deposition rate and inverse of glass temperature (1/T, in °K-1) for different emissions during the SaliFa 2 campaign.

Figure 7 Variations in the deposition rate as a function of the deviation between air and glass temperature (°K).

Campaign Non-treated glass


Coating with roughness value of 2 mm



SaliFa 1 3.0.10-5 2.8.10-5 1.2.10-4 9.6.10-5 1.2.10-4

SaliFa 2 1.5.10-5 1.1.10-5 5.1.10-5 4.2.10-5 4.5.10-5

Average values 2.2.10-5 1.9.10-5 8.5.10-5 6.9.10-5 8.2.10-5

Table 1 Average dry deposition rates of aerosols (m.s-1) determined for different substrates during the SaliFa 1 and 2 short-term campaigns in June 2005 and June 2006 (maximum uncertainty 58%).


concerning the assessment of deposition rates on urban substrates.

Nevertheless, the studies conducted by Roed (1983, 1985, 1986,

1987) allow for a comparison of certain data. In particular, Roed

determined the dry deposition rates of aerosols on different urban

substrates based on the cesium-137 (137Cs) released to the atmo-

sphere during nuclear atmospheric tests prior to the Chernobyl

accident, and based on the various radionuclides released further

to the accident. He also used the 7Be naturally present in the

atmosphere as a dry deposition tracer.

In the studies conducted prior to the Chernobyl accident [Roed,

1983, 1985], the author indicated that the particle size distribution

of 137Cs obtained from the atmospheric tests was not perfectly

accurate, but probably close to that of 7Be, which had a mean

aerodynamic diameter of 0.4 µm. The deposition rate values obtained

were very low. For vertical surfaces, the deposition rates determined

from 137Cs measurements were less than 1.10-4 m.s-1. The values

obtained for 7Be were approximately 1.6.10-4 m.s-1, i.e. very close

to those obtained for 137Cs.

In the studies conducted after the Chernobyl accident (Table 4),

[Roed, 1986, 1987], the author determined the dry deposition rates

for iodine-131 (131I), cesium-137 (137Cs), ruthenium-103 (103Ru),

barium-140 (140Ba), cerium-144 (144Ce) and zirconium-95 (95Zr).

Roed listed the following mean aerodynamic diameter values: 0.4 µm

exposure time) and August 2006 (after 8 months of exposure time).

The exposure time was therefore variable, but given the half-life

of 7Be (53.2 days), the average exposure time of the specimens was

considered to be two months.

The results obtained are listed in Table 2. Dry deposition rates

ranged from 3.2.10-5 to 3.9.10-5 m.s-1 for non-treated glass and from

1.4.10-5 to 3.4.10-5 m.s-1 for low-maintenance glass. For façade

coatings, dry deposition rates ranged from 1.1.10-4 to 3.4.10-4 m.s-1.

In all cases, the uncertainty associated with the deposition rate was

less than 54%.

The deposition rates for glass specimens were systematically lower

than for coating specimens, which is consistent with the results

obtained during the short-term experimental campaigns. As in the

case of the short-term campaigns, no significant variations were

observed between different glass types, or between different coating

types.

In addition, the dry deposition rates measured during the short-term

and long-term campaigns were of the same order of magnitude

(Table 3), with a deviation less than a factor of three.

Comparison with results in the "literature"

The international "literature" contains little experimental data

1. 3

Exposure time

Non-treated glass

Low-maintenance

glass




April 2005 – December 2005 3.9.10-5 3.4.10-5 2.3.10-4 1.5.10-4 1.1.10-4

April 2005 – April 2006 – * – * 2.8.10-4 2.6.10-4 3.4.10-4

December 2005 – April 2006

3.2.10-5 1.4.10-5 2.1.10-4 1.7.10-4 1.7.10-4

Average values 3.5.10-5 2.4.10-5 2.4.10-4 1.9.10-4 2.1.10-4

Table 2 Average dry deposition rates of aerosols (m.s-1) determined for different substrates during the long-term exposure campaign (*: non-significant measurements, maximum uncertainty 54%).

Campaign Non-treated glass

Low- maintenance

glass




Short-term 2.2.10-5 1.9.10-5 8.5.10-5 6.9.10-5 8.2.10-5

Long-term 3.5.10-5 2.4.10-5 2.4.10-5 1.9.10-4 2.1.10-4

Long-term to short-term ratio

1.6 1.3 2.8 2.7 2.6

Table 3 Comparison of dry deposition rates of aerosols (m.s) determined during the long-term and short-term experimental campaign.



the different studies, the results obtained have been considered as

consistent.

Conclusion

As part of the SaliFa-PRIMEQUAL research program, several

field test campaigns were conducted to measure the dry depo-

sition rates of aerosols in an urban environment by means of

glass specimens and façade coating specimens.

These deposition rates were obtained using two complemen-

tary methods. The first method consisted of using a tracer of

the deposition of fluorescein aerosols artificially generated

during two short-term experimental campaigns (SaliFa 1 and

2). The second method consisted of using 7Be, a radionuclide

naturally present in the atmosphere in aerosol form, as a tracer

of the deposition generated during a long-term experimental

campaign.

In the short-term campaigns, the deposition rates ranged from

1.1.10-5 to 3.0.10-5 m.s-1 for glass specimens and from 4.2.10-5 to

1.2.10-4 m.s-1 for façade coating specimens. In the long-term

campaign, where test specimens were exposed to an urban

atmosphere for 8 to 12 months, the dry deposition rates mea-

for 131I, 137Cs and 103Ru, and 1 to 4 µm for 140Ba, 144Ce and 95Zr. For

aerosols with a mean aerodynamic diameter of 0.4 µm, the average

deposition rates on glass surfaces and walls were given as 8.2.10-5

m.s-1 and 1.2.10-4 m.s-1, respectively, with significant variations (of

more than one order of magnitude) depending on the radionuclide.

For aerosols with a mean aerodynamic diameter of 1 to 4 µm, the

average deposition rates on glass surfaces and walls were given as

1.5.10-5 m.s-1 and 8.7.10-5 m.s-1, respectively (Table 4) also with

significant variations in deposition rate depending on the radionu-

clide considered, which were difficult to explain for radionuclides

transported by natural aerosols (especially over long distances).

The average dry deposition rates determined during the SaliFa 1

campaign (glass: 2.9.10-5 m.s-1; coatings: 1.1.10-4 m.s-1) were close

to those resulting from Roed’s studies (glass surfaces: 8.2.10-5

m.s-1; walls: 1.2.10-4 m.s-1), particularly in the case of deposition

rates on walls. The average dry deposition rates determined during

the SaliFa 2 campaign were lower than for the SaliFa 1 campaign

(glass: 1.3.10-5 m.s-1; coatings: 4.6.10-5 m.s-1) but still in good agree-

ment with Roed’s results.

The average dry deposition rates determined during the long-term

experimental campaign (glass: 3.0.10-5 m.s-1; coatings: 2.1.10-4 m.s-1)

were close to those resulting from Roed’s studies.

Taking into account the measurement uncertainty associated with

1. 3

Reference data set Aerosol type Aerosol diameter (µm)

Dispersion rate on glass surfaces (m.s-1)

Dispersion rate on walls (m.s-1)

Short-term campaign: SaliFa 1

Fluorescein 0.2 2.9.10-5 1.1.10-4

Short-term campaign: SaliFa 2

Fluorescein 0.2 1.3.10-5 4.6.10-5

Long-term campaign 7Be 0.4 3.0.10-5 2.1.10-4

Roed 1986,1987 131I 0.4 2.3.10-4 3.0.10-4

Roed 1986,1987 137Cs 0.4 5.0.10-6 1.0.10-5

Roed 1986,1987 103Ru 0.4 1.0.10-5 4.0.10-5

Roed 1986,1987 140Ba 1 to 4 2.0.10-5 4.0.10-5

Roed 1986,1987 144Ce 1 to 4 — 9.0.10-5

Roed 1986,1987 95Zr 1 to 4 1.0.10-5 1.3.10-4

Table 4 Comparison of dry deposition rates obtained by Roed (1986, 1987) and those obtained during the SaliFa short-term and long-term campaigns.


1. 3

Acknowledgements

This study was funded by the French Ministry for Ecology and

Sustainable Development (through Ademe, the environmental

and energy management agency) and conducted in collabora-

tion with the National Center for Building Science and

Technology (CSTB, Nantes, Marne-la-Vallée and Grenoble), the

Interprofessional Research Center for Aerothermochemistry

(Coria, Rouen) and the Central Research Institute in Nantes

(ECN).

sured using 7Be ranged from 1.4.10-5 to 3.9.10-5 m.s-1 for glass

specimens and from 1.1.10-4 to 3.4.10-4 m.s-1 for coating speci-

mens. The results obtained with fluorescein aerosols for short

exposure times (1 hour) and with 7Be aerosols for long expo-

sure times (several months) are very similar.

Future studies will aim to quantify dry deposition as a function of

micrometeorological conditions (turbulent parameters), and to

accurately determine the associated impact of thermophoresis.

References

AFNOR NFX 44-011 (1972). Séparateurs aérauliques - Méthode de mesure de l’efficacité des filtres au moyen d’un aérosol d’uranine (fluorescéine), 12 p.

Boulaud and Renoux (1998). Les aérosols, Physique et Métrologie, Lavoisier TEC et DOC, 291 p.

D. Maro, D. Boulaud, A. Copalle, P. Germain, D. Hébert, L. Tenailleau (2004). Validation of dry deposition models for submicronic and micronic aerosols. Proceedings of 9th Int. Conf. on harmonization within Atmospheric Dispersion Modelling for Regulatory Purposes, Garmisch-Partenkirchen, p. 89-94, 1-4 June 2004.

J. Roed (1983). Deposition velocity of caesium-137 on vertical building surfaces, Atmospheric Environment., 17, 3.

J. Roed (1985). Run-off from roofs, Risö-M-2471.

J. Roed (1986). Dry deposition in urban areas and reduction in inhalation dose by staying indoors during the Chernobyl accident, paper presented at a meeting 12 june 1986 of the group of experts on accident consequences (GRECA), NEA/OECD, Paris.

J. Roed (1987). Dry deposition on smooth and rough urban surfaces, The post-Chernobyl workshop, Brussels, 3-5 February 1987, NKA/AKTU-245 (87)1.

C. Sacré, J.-P. Flori, D. Giraud, F. Olive, B. Ruot, J.-F. Sini, J.-M. Rosant, P. Mestayer, A. Coppalle, M. Talbaut, D. Maro, O. Connan, D. Hébert, P. Germain, M. Rozet (2006). Salissures de façade, Programme PRIMEQUAL, Rapport CSTB EN-CAPE 06.009, 54 p.


Context of atmospheric radioactivity monitoring programs

Artificial radionuclides were first considered as indicators of inter-

national nuclear weapons tests in the atmosphere, and subse-

quently as indicators of radioactive contamination [Bouisset et al,

2004]. Most of the radionuclides produced during nuclear tests(1)

have disappeared through radioactive decay due to their short

half-life. Cesium-137 (137Cs) is one of the main indicators (often the

only one) used by European and international atmospheric radio-

logical monitoring networks, particularly on account of its half-life

(30.2 years) and relative ease of measurement (by direct gamma

spectrometry). Figure 1 shows that during the period of atmo-

spheric nuclear tests (1945-1980), each test produced a rapid increase

in 137Cs activity, followed by a decrease by a factor of two in the next

six months, thus showing the importance of deposition mecha-

nisms.

Olivier MASSON, Damien PIGA, Philippe RENAUD, Lionel SAEY, Pascal PAULATContinental and Marine Radioecological Studies Laboratory

Anne DE VISME-OTTEnvironmental Radioactivity Measurements Laboratory

The year 2008 marks the 50th anniversary of the establishment in France of atmospheric radioactivity monitoring

programs to regularly monitor the presence of natural and artificial radionuclides in the atmosphere. These

programs rely on regular sampling and measurements of atmospheric suspended dust particles (aerosols) to

identify radionuclides present in the atmosphere and determine their current activity at adult height level. This

radioecological monitoring program integrates radiation protection objectives, including:

ensuring early detection of the arrival of radioactive plumes (alarm system);

ensuring the measurement of low-level reference values to assess the impact of recent contamination episodes,

regardless of magnitude.

Recent monitoring campaigns were based in particular on the detection of natural and artificial radionuclides

present in the atmosphere with a view to better assessing the potential long-term impact of accidental release.

This assessment relies on studies aimed at understanding the mechanisms underlying atmospheric transfers to

and from the terrestrial compartment. Current research seeks to identify the mechanisms that potentially delay

the return to initial conditions prior to an accidental release.

CONTRIBuTIONS OF ARTIFICIAl ATMOSPHERIC RADIONuClIDE MONITORINg to the study of transfer processes and the characterization of post-accidental situations

1. 4

(1) In particular, iodine-131, barium-140, ruthenium-103, ruthenium-106, cerium- 141, cerium-144, strontium-89, strontium-90, yttrium-91, zirconium-95, manganese-54, iron-55, and plutonium isotopes.


1. 4

1970 to 1986, measurement durations were multiplied by five. From

1980 to 1986, detection efficiency increased by a factor of four, and

from 1996 to 2002 it increased again by a factor of two. In addition,

from 1993 to 2004, detector background noise levels were reduced

by a factor of 10. All of these improvements proved to be necessary

to meet the objectives of "low-level" radiological monitoring programs,

since during the same period (from 1958 to 2008) aerosol-borne

artificial radioactivity levels decreased by a factor of 10,000.

Under severe reactor accident conditions, 137Cs would probably

be released to the environment, temporarily resulting in activity

concentrations in the atmosphere one or more orders of magni-

tude higher than current levels. During accident and post-accident

phases, an adequate knowledge of the contamination level prior

to the event could be used to quantify the impact of release to

the atmosphere.

The Chernobyl accident reloaded the atmosphere dramatically

(increase of average activity levels by a factor of 106 over a ten-

day period [Renaud et al, 2007]). In 1997, cesium-137 activity in

the atmosphere had dropped back to the same level as before the

accident, i.e. approximately 10-6 Bq.m-3. In late May 1998, the

incineration of a 137Cs source in Algeciras (Spain) multiplied the

activity concentration by 2,500 for a few days, but did not disrupt

the generally decreasing trend for any length of time.

This decrease in activity between two successive tests was used to

predict the 99% depletion of the radionuclide stock in the atmo-

sphere after only five to six years. Although still perceptible from

one year to another until the late 1990’s, this depletion has slowed

considerably due to a residual contribution via the resuspension of

radionuclides previously deposited on soils.

Figure 2 shows the radionuclides regularly monitored in France

based on samples collected by IRSN OPERA stations(2) during the

past six years.

137Cs is the only artificial radionuclide that is still frequently mon-

itored in the atmosphere in France(3). The ability to measure trace

quantities of cesium-137 (down to 10-8 Bq.m-3 of air) make it a

particularly valued means for characterizing past events, as well as

potential situations in the event of accidental release.

The annual average activity concentration of cesium-137 is cur-

rently 0.25 Bq per million cubic meters of air (0.25.10-6 Bq.m-3),

the lowest value ever observed since the beginning of the moni-

toring program. This average activity is derived from measurements

taken every ten days at nine sites in France. Each of these sites is

equipped with an OPERA aerosol sampling station.

Cesium-137 can only be detected by implementing specific devices

used to concentrate compounds present in trace quantities, and by

improving the sensitivity of measuring devices. From 1960 to 1980,

the quantity of air filtered per measurement was multiplied by 50,

and currently amounts to 70,000 m3 over a five-day period. From

19591961

19631965

19671969

19711973

19751977

19791981

19831985

19871989

19911993

19951997

19992001

20032005

2007

10

10-1

10-2

10-3

10-4

10-5

10-6

10-7

10-8

1

Bq per m-3 of air

Fallout from atmospheric nuclear tests

Chernobyl accident

Algeciras incident

Figure 1 Cesium-137 activity in the air in France from 1959 to 2007. Aerosol samples taken by OPERA stations (the observatory for continuous monitoring of environmental radioactivity).

(2) Continuous environmental radiation monitoring network.

(3) In recent short-term studies, other artificial radionuclides (239Pu, 240Pu) were also detected at levels of approximately 10-9 Bq per m3 of air.



1. 4

depositions into the atmosphere, since their role was masked by

the predominant impact of the fallout from nuclear atmospheric

tests. The gradual disappearance of this contamination has made

it possible to identify these timeless mechanisms, which are now

recognized as being responsible for maintaining the long-term

persistence of activity in the lower layers of the atmosphere and

determining its variability.

In the absence of new atmospheric releases of 137Cs, the only

residual source is the "stock" accumulated over the years in soil.

Due to its affinity with clays and organic materials, 137Cs remains

for the most part in the first 10 to 15 centimeters of the soil. The 137Cs present in the soil surface layer can be reinjected into the

lower atmosphere under the repeated action of wind erosion.

Due to the very low activity concentrations currently observed in

the atmosphere, the slightest resuspension of soil particles contain-

ing 137Cs in quantities ranging from a few hundred to a few thousand

de Bq/m2 (in France) is sufficient to momentarily vary the atmo-

spheric activity concentration. These characteristics make 137Cs a

relevant tracer for the study of soil-atmosphere exchanges, in the

same manner that 7Be is used to trace the descent of strato-

spheric air into the lower atmospheric layers and 210Pb is used to

trace continental air masses [Papastefanou, 2008]. For a normal

sampling period of 10 days(4), a variability reflected by the regular

occurrence of activity peaks is observed (Figure 3).

Improving knowledge of atmospheric trans-fer mechanisms for a better assessment of variations in atmospheric activity concen-trations under post-accident conditions

137Cs is also used as a tracer to determine the natural transfer mech-

anisms that contribute to keeping it at trace levels in the atmosphere.

Like many radionuclides, it is present in the atmosphere in articulate

form and is therefore subject to laws governing the evolution of

aerosol concentrations. Aerosols transported in the atmosphere are

deposited through dry or wet processes. The quantification of aero-

sol deposition is therefore essential with regards to both impact

assessments (since it is through these atmospheric deposition

mechanisms that aerosols can potentially affect the functioning of

ecosystems) and methodology (when correctly quantified, aerosol

deposition can be used in conjunction with concentration levels to

validate numerical simulations with high levels of constraint).

Since the mid-1990’s, the decrease in cesium-137 activity in the

atmosphere in France has slowed considerably, to the extent that

the average activity concentration has stabilized since the year 2000.

This observation indicates the following:

the original source, i.e. fallout from nuclear atmospheric tests

and from the Chernobyl accident, has practically disappeared;

there is an equilibrium between dry or wet deposition mechanisms

and atmospheric injection mechanisms, e.g. resuspension of particles

from the soil surface by wind erosion or dispersion of flying ashes

from forest fire plumes.

Until the 1990’s, it was practically impossible to explicitly take into

account the mechanisms responsible for the reinjection of old

* Detected sporadically (or exceptionally)

Activity levels (µBq.m-3)

** Mainly of natural origin

*** Detected during studies

7Be

210Pb

40K

234Th**

228Ac*

22Na**

137Cs

239+240Pu***

Natural Artificial104

103

102

101

10

10-1

10-2

10-3

10-4

Depletion of atmospheric

stock

Combination of atmospheric fallout and resuspension

from soils

Equilibrium between deposition and

reinjection processes

1988 1990 1992 1994 1996 1998 2000 2002 2004 20061986

10-2

10-3

10-410

-6

10-7

10-5

10-6

10-7

137Cs (Bq.m-3)

10-6-6

10-7

Figure 2 Variation in activity levels of main natural and artificial radionuclides present in the atmosphere in aerosol form in France, from 2000 to 2007.

Figure 3 Evolution of average annual atmospheric activity concentration of 137Cs in France since the Chernobyl accident, and detail of results obtained over ten-day periods.

(4) This variability is even more pronounced when measured exceptionally on a five-day-old sample.


1. 4

in 137Cs activity by a factor of three, whereas oceanic air masses

generally exhibit an average activity three times lower [Masson et al,

2007]. These low levels are explained by the lower dust load in west-

erly winds, and by the frequently associated rains that clean the

atmosphere (Figure 5).

Based on this analysis, it can be concluded that the "background

noise" associated with oceanic air masses amounts to approxi-

mately 0.1 µBq.m-3 (from 0.03 to 0.2 µBq.m-3) and therefore con-

stitutes the absolute current reference value for continental France.

This knowledge of the relation between air mass origin and cesium

activity concentration can be used to assess the significance of a

release and to formulate explanations for an observed increase in

activity concentration.

Resuspension

Soil particle resuspension constitutes a diluted and delayed source

of radionuclides in the atmosphere [Holländer and Garger, 1996;

Johansen et al, 2003]. Dust load measurements performed by certi-

fied air quality monitoring agencies in "background" rural stations(5)

indicate that PM10

(6) are more or less constant (approx. 15 µg.m-3)

from western to eastern France during westerly winds (Figure 6).

A statistical analysis of a large number of situations between 2000

and 2006 led to the identification of an increasing average longitu-

dinal west-to-east gradient of the atmospheric activity concentra-

tion of 137Cs. As a result, the variations in activity concentration

Parameters and processes involved in the variation of 137Cs activity

Air mass origin

A detailed analysis of air mass advection conditions at six OPERA

stations from 2000 to 2006 has led to the identification of air mass

origin as one of the parameters associated with these variations

(Figure 4). The study of over 14,000 daily "retrotrajectories" has

established a nearly systematic relation between the occurrence of

activity peaks and the presence continental air masses (easterly wind).

In certain rare cases, a relation with a Saharan origin can be established.

Continental air masses are accompanied by an average increase

137Cs activity concentration in atmosphere (µBq/m3)

Oceanic air masses

June2002

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

September January2003

January2004

April JulyApril

2

1.8

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

Continental air masses Saharan dust fallout episodes

Figure 4 Peak 137Cs activity levels in the atmosphere resulting from long-distance aerosol transport (e.g. at Dijon during easterly winds (left) and at La Seyne-sur-Mer in the presence of a Saharan air mass (right) [Masson et al, 2007]. The other points correspond to air masses having partially or exclusively overflown ocean surfaces during the five days preceding their arrival at the sampling station.

1.0

Greenwich Longitude (° decimals)

-1.0 3.0 5.0 7.0

0.1

0.2

0.3

0.4

0.5

0.6

activity concentration in soil activity concentration in soil

6,000

5,000

4,000

3,000

2,000

1,000

00.0

137Cs activity concentration in atmosphere (µBq/m3)

(µBq/m3) (Bq/m2)

137Cs activity concentration in soil (Bq/m2)

Figure 5 Comparison of average activity concentrations of 137Cs in the atmosphere and in the soils near the OPERA sampling stations, as a function of longitude [Masson et al, 2007].

(5) Stations used to monitor the average exposure of rural populations and environ-ments to "background" atmospheric contamination. This background contamina-tion is generally due to long-distance air mass transports, particularly transborder transports http://www.buldair.org/Definition/Typologie.htm.

(6) Particle with a mean aerodynamic diameter less than or equal to 10 microns.



1. 4

easterly wind conditions exhibit a variability four times higher. This

higher variability is also accompanied by a higher average activity

concentration due to higher particle concentrations and dust activity

concentrations (Figure 6), particularly during forest fires ("biomass

fires"). As a result, it can be estimated that the contribution of distant

resuspension during easterly winds is three to four times higher than

that of local resuspension (Figure 7).

Saharan dust fallout

These phenomena are the exacerbated result of resuspension

processes. The arrival of Saharan air masses transporting large

quantities of dust is an easily detectable radiological event, since

gradient from one station to another can be attributed to differ-

ences in 137Cs specific activity levels in resuspended dust, and there-

fore in soils. The existence of a proportional relationship between

the activity concentrations of 137Cs in the atmosphere and in the

soil at each OPERA site is indicative of a local resuspension

contribution (Figure 7). An additional confirmation of this local

contribution is given by the strong correlation between the activity

concentration of 137Cs and the concentration of large particles

suspended in air, which travel only over very short distances before

they are redeposited (in the order of a few hundreds or thousands

meters).

This local contribution is occasionally combined with a distant con-

tribution in the case of continental air masses. In such cases, the

average dust load decreases from east to west and the variations in

activity concentration are identical to those associated with west-

erly winds, but with higher concentrations. This demonstrates that

the contribution of the long-range transport of particles resuspended

from soils contaminated with 137Cs is on the whole greater than that

of French soils, and attributable to the distribution of fallout from the

Chernobyl accident (distribution largely determined by the total

amount of rain observed during the week after the accident).

In an initial approximation, it can be assumed that the contribution of

local resuspension is the same during easterly and westerly winds. This

local contribution can therefore be subtracted from easterly wind

conditions to determine the distant contribution of easterly winds.

Westerly wind conditions are relatively standardized and do not

exhibit a significant variability in atmospheric concentration of 137Cs

as a function of longitude from one case to another. On the contrary,

PM10 (µg.m-3) PM10 (µg.m-3) 137Cs (µBq.m-3) 137Cs (µBq.m-3)

Longitude (°) Longitude (°)

Westerly wind conditions Easterly wind conditions

-1.5 -0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5

30

25

20

15

0.5

0.4

0.3

0.2

0.1

0.0

0.8

0.9

1.0

0.3

0.4

0.5

0.6

0.7

0.2

0.1

0.0

10

5

0

35

40

30

25

10

5

0

35

40

-1.5 -0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5

20

15

Figure 6 Longitudinal variations of dust load levels and 137Cs activity levels in the atmosphere in France.

137Cs (µBq.m-3)

Longitude (°)

R2 = 0.7594

-1 Greenwich 1 2 3 4 5 6 7

0.6

0.7

0.5

0.4

0.3

0.2

0.1

0.0

0.8

0.9

1.0

Oceanic air masses

Continental air masses

R2 = 0.6690

Figure 7 Variations in atmospheric activity concentration of 137Cs observed in France, as a function of air mass origin and longitude.


1. 4

Large-scale forest fires took place on several occasions in 1992

and more recently in 2002, 2003 and 2006 in regions of Belarus,

Ukraine and Russia contaminated by fallout from the Chernobyl

accident and exhibiting high levels of cesium-137 contamination

in soils and vegetation. According to data collected by OPERA

stations, in 2002 and 2006 easterly winds brought flying ash and

smoke to western Europe, causing an increase of the atmo-

spheric activity concentration of cesium-137 in France by a

factor of 2 to 10, depending on the station. Figure 8 shows the

air mass trajectories of September 5, 2002 from forest fires in

regions contaminated by the Chernobyl accident.

It is estimated that approximately two thirds of the significant

increases in atmospheric activity concentration of cesium-137 in

France over the past eight years are due to local or distant resuspen-

sion or reinjection by biomass fires. The remaining third is mainly

observed during winter and can be attributed for the most part to

meteorological unfavourable dispersion conditions, particularly

inversions of the vertical temperature gradient. Under such condi-

tions, all atmospheric contaminants remain concentrated between

the soil and an altitude that varies in the course of the day. 137Cs

does not escape this rule, although the levels attained do not pose

a health risk.

Radioecological sensitivity of high altitude sites

Altitude is also an important parameter influencing the magnitude

of atmospheric activity levels. The contribution of long-range

the ambient activity concentration of 137Cs is extremely low [Pham

et al, 2005]. France (particularly southern France) is regularly sub-

ject to Saharan dust deposition events (about 20 events per year)

of variable magnitudes and generally associated with low precipita-

tion [Pham et al, 2005]. Depositions are observed ranging from a

few tens to a few hundred mg per square meter, and occasionally

over 10 g per square meter in exceptional cases. During these events,

which, on an average, last two to three days, the quantity of dust

lifted and transported over distances of up to several thousand

kilometers can amount to thousands or even millions tons. The

conjunction of an intense flux of particles with 137Cs activity con-

centrations at trace levels can result in several episodes (or even in

a single episode) producing a 137Cs deposition equivalent to that

observed on average throughout an entire year, momentarily exhib-

iting significant activity concentrations (10 or even 30 times

higher than the ambient level) [Masson et al, 2005].

The current contribution of these episodes in terms of additional

soil activity remains negligible (less than 0.1% of the activity

already present). The same is true for the resulting exposure doses

due to dust inhalation (approximately 10-10 Sv), as compared to

the average annual exposure doses due to natural radiation in France

(2.3 mSv/year).

Saharan dust fallout episodes indicate a possible redistribution of

the artificial radioactivity resulting from the global fallout of nucle-

ar atmospheric tests(7).

These extreme episodes are being monitored as part of the EXTREMA

project coordinated by IRSN and funded by the French National

Research Agency, within the framework of the Environmental and

Climate Vulnerability research program). In a climate change context

directly or indirectly related to anthropogenic pressure, these

episodes need to be accurately monitored [Moulin, 2005]. By study-

ing the intricate mechanisms involved in these episodes (e.g. par-

ticle segregation as a function of size during transport, or

interactions between suspended particles), it is possible to acquire

a better understanding of the transfers occurring during more

common resuspension events.

Biomass fires

Sporadic forest fires or seasonal burning (particularly during spring)

also contribute to the injection of dust into the lower atmospher-

ic layers. Like Saharan dust fallout episodes, biomass fires generate

intense particle fluxes. Radionuclide transport by biomass fires has

been observed on several occasions and could pose a health risk

for firefighters and local populations in the case of fires occurring

in contaminated areas [Yoschenko et al, 2006].

Figure 8 Air mass trajectories of September 5, 2002 from forest fires in contaminated areas (major fires shown in red), plotted using the Hysplit model.



1. 4

These results can apparently be extrapolated to other high altitude

sites, on the condition that they exhibit a high proportion of fog

hours, as in the case of the Puy-de-Dôme (45%).

By extension, other types of cloud formations, such as plain or

coastal fogs, could lead to "occult" depositions that should be taken

into account, if they coincide with accidental release to the atmo-

sphere. At present, this type of deposition is generally not explic-

itly considered in models.

Conclusion

Programs to monitor the presence of artificial radioactivity in the

atmosphere rely on the historical monitoring of 137Cs levels. 137Cs

is a good indicator of the behavior of a large number of radionu-

clides potentially released into the environment in particle form

under accident conditions.

Current levels appear close to detection limits more and more

often, while many questions remain only partially answered. To

continue to ensure significant monitoring, longer sampling

periods are theoretically needed (ten days of routine sampling)

to allow a sufficient number of particles (and therefore bec-

querels) to accumulate in the filters. However these sampling

periods constitute a limitation for the fine interpretation of

transfers during short-term episodes such as rainfall events (≤

approximately one day), "temperature inversions" (half a day),

Saharan episodes (two to three days) or the advection of conti-

nental air masses (three to four days). In order to overcome this

difficulty, IRSN OPERA stations are currently being upgraded

in order to increase sampling rates and thereby reduce sam-

pling periods, thus allowing finer time-based discretization of

changes in air mass activity levels. The interpretation of such

episodes should make it possible to identify the most radioeco-

logically sensitive conditions, and to characterize the most

extreme climatic events. On a more general note, this upgrade is

part of the program to completely overhaul the French atmo-

spheric radioactivity monitoring network.

resuspension is more apparent in mountain ranges, which intercept

Saharan dust clouds or clouds of particles lifted to these altitudes

by the thermal energy released by forest fires. In both cases, the

mechanical or thermal energy involved is extremely significant,

allowing the particles to reach high altitudes (from 1000 to 6000 m)

and travel over distances of hundreds or even thousands of kilo-

meters [Goudie and Middleton, 2001].

During a Saharan dust fallout episode in May 2006, it was noted

that the activity concentration was 10 times higher at the top of

the Puy-de-Dôme (1465 m) than at its base (645 m), and up to

100 times higher at the Jungfraujoch station in Switzerland

(3454 m) [Flury and Volkle, 2008]. The average annual atmo-

spheric activity concentration of 137Cs at the top of the Puy-de-

Dôme is two times higher than the average value obtained 800

meters further below, despite the dust load being five to ten times

lower at the higher altitude. These studies show the higher radio-

logical sensitivity of high-altitude sites and the interest of setting

up "sentinel" stations at high altitudes to ensure early detection

of intercontinental transport of atmospheric contamination

plumes.

Altitude also plays an indirect role in terms of deposition, par-

ticularly due to more abundant precipitation [Nguyen-Ba-Cuong,

1967]. It should be noted that deposition, particularly 137Cs depo-

sition, is generally a function of mean annual precipitation [Renaud

and Roussel-Debet, 2007]. At the top of the Puy-de-Dôme,

the 137Cs inventory in soil is higher than the values evaluated via

a rainfall-deposition relation established for plain level sites [Le

Roux et al, 2008]. This is probably due to fog deposition processes,

which are generally not considered as wet deposition processes

because the quantities of water involved remain too low to be

recorded by conventional rain gauges. The term "occult" deposition

is therefore used. As a result, even in the absence of rain, the mere

presence of a cloud at the top of a mountain can lead to the

deposition of radionuclides through contact with the soil or plant

cover. Recent studies conducted using specific equipment in col-

laboration with the Physical Meteorology Laboratory (Lamp)(8)

have confirmed the potential of clouds to rain-out aerosols and

associated radionuclides (see News Flash, [O. Connan et al]), with

the detection of comparable activity concentrations of 137Cs in

cloud and rain water (0.5 mBq.l-1).

(7) The ratios between plutonium isotopes present in trace quantities in dust particles recently deposited in France are characteristic of global fallout and cannot be specifically attributed to French nuclear tests performed in the Sahara in the 1960’s [Masson et al, 2007].

(8) Earth Physics Institute of Clermont-Ferrand (OPGC), Physical Meteorology Laboratory (Lamp), UMR 6016 CNRS/Blaise Pascal, Clermont-Ferrand.


1. 4

References

P. Bouisset, E. Barker, O. Masson, R. Gurriaran, X. Cagnat, D. Mekhlouche, S. Aubry, M. Hadjaj, L. Saey (2004). Concentration de 137Cs et de 7Be dans les aérosols en France de 1959 à 2002. Radioprotection vol 39 n° 3, 2004.

T. Flury, H. Völkle (2008). Monitoring of air radioactivity at the Jungfraujoch research station: Test of a new high volume aerosol sampler. Science of the Total Environment, 391(2008), 284-287.

A.-S. Goudie, N.-J. Middleton (2001). Saharan dust storms: Nature and consequences. Earth Science Reviews 56-179-204.

W. Holländer, E. Garger (1996). Contamination of surfaces by resuspended material. Experimental collaboration project n° 1. Final report. European Commission. EUR 16527 EN. ISBN 92-827-5192-9.

M.-P. Johansen, T.-E. Hakonson, F.-W. Whicker, D.-D. Breshears (2003). Pulsed redistribution of a contaminant following forest fire: Cesium-137 in runoff. Journal of Environmental Quality 32(6): 2150-2157.

G. Le Roux, L. Pourcelot, O. Masson, C. Duffa, F. Vray, P. Renaud (2008). Aerosol deposition and origin in French mountains estimated with soil inventories of 210Pb and artificial radionuclides. Atmospheric Environment 42 (2008), 1517-1524.

O. Masson, L. Saey, P. Paulat, D. Piga, G. Le Roux, L. Bourcier, X. Cagnat (2007). Relation entre l’origine des masses d’air et l’activité en 137Cs dans les aérosols en France, de 2000 à 2006. Rapport IRSN/DEI/SESURE n° 2007-01.

O. Masson, L. Pourcelot, R. Gurriaran, P. Paulat (2005). Impact radioécologique des retombées de poussières sahariennes. Épisode majeur du 21/02/2004 dans le sud de la France. Rapport IRSN/DEI/SESURE/2005-04.

C. Moulin (2005). Intensification du transport des poussières d’Afrique depuis 35 ans : relations avec les changements climatiques et avec l’augmentation de la population au Sahel. CEA/LSCE (séminaire LSCE janvier 2005 Saclay).

Nguyen-Ba-Cuong, G. Lambert (1967). Rôle du relief dans le taux de retombées radioactives.

C. Papastefanou (2008). Radioactive nuclides as tracers of environmental processes. Radioactivity in the Environment 12, p. 59-70.

M.-K. Pham, J.-J. La Rosa, S.-H. Lee, B. Oregioni, P.-P. Povinec (2005). Deposition of Saharan dust in Monaco rain 2001-2002: Radionuclides and elemental composition. Physica Scripta. Vol. T118, 14-17, 2005.

Ph. Renaud, D. Champion, J. Brenot (2007). Les retombées radioactives de l’accident de Tchernobyl sur le territoire français. Éditions Tec & Doc. Collection Sciences et techniques. Lavoisier. ISBN : 978-2-7430-1027-0.

Ph. Renaud, S. Roussel-Debet (2007). 137Cs in French soils: Deposition patterns and 15-years evolution. Science of the Total Environment, Vol. 374, Issue 2-3, 388-398.

V.-I. Yoschenko, V.-A. Kashparov, V.-Protsak, S.-M. Lundin, S.-E. Levchuk, A.-M. Kadygrib, S.-P. I. Zvarich, Yu.-V. Khomutinin, I.-M. Maloshtan, V.-P. Lanshin, M.-V. Kovtun, J. Tschiersch (2006). Resuspension and redistribution of radionuclides during grassland and forest fires in the Chernobyl exclusion zone: part I. Fire experiments. Journal of Environmental Radioactivity 86 (2006), p. 143-163; part II. Modelling the transport process. Journal of Environmental Radioactivity 87 (2006), p. 260-278.



IRSN teams have been conducting research

on natural and artificial atmospheric radio-

activity by studying atmospheric aerosol

transport mechanisms and dry and wet

deposition conditions. From March 13 to

21, 2007, two IRSN laboratories (LRC and

LERCM) conducted a field test campaign on

the slopes of the Puy-de-Dôme, in collabo-

ration with the Physical Meteorology

Laboratory (Lamp)(1). Samples of aerosols,

water vapor, cloud water, rain water and

snow were collected. Measurements of 7Be, 212Pb, 214Pb, 210Pb, 210Po, 212Po, 214Po, 40K, 137Cs

and 3H activity in atmospheric aerosols,

cloud vapor water and rain water were taken

in three sites at different altitudes near

Clermont-Ferrand (Cézeaux 405 m, Opme

660 m, Puy-de-Dôme 1465 m).

Considerable experimental analytical

resources were implemented for this study

(Figure 1). In particular, measurements of

short-lived gamma and alpha radionuclides

were performed in a laboratory van imme-

diately after sampling. Innovative sampling

systems were used (Figure 2): the PREVAIR

atmospheric water vapor sampling system,

used to collect water vapor for 3H concen-

tration measurements, cloud water collec-

tors used to collect droplets suspended in

clouds (installed at the Puy-de-Dôme site),

and aerosol samplers based on high-rate

filtration.

(1) Earth Physics Institute of Clermont-Ferrand (OPGC), Physical Meteorology Laboratory (LAMP), UMR 6016 CNRS/Blaise Pascal.

Olivier CONNAN, Denis MARO, Didier HÉBERT, Luc SOLIER

Radioecology Laboratory of Cherbourg-Octeville

Olivier MASSON, Gaël LE ROUX, Laureline BOURCIER

Continental and Marine Radioecological Studies Laboratory

1.5"ATMoSPHERiC AERoSoL wASHouT AND CLEANiNG" CAMPAiGN (Puy-de-Dôme): characterization of atmospheric radioactivity at three sites located at different altitudes

Figure 1 Collection systems deployed during measurement campaigns.

Meteorological station (PM10 measurements)

Atmospheric deposi-tion collector

Trace metal collector (aerosol filters)

water vapor collector

Rain water collector

Aerosol impactor



The measurements obtained were used

to assess aerosol washout efficiency within

and below clouds, to characterize the radio-

activity of air masses, and to acquire data

on aerosol radioactivity as a function of size

class. Two distinct meteorological situations

were studied: continental air masses origi-

nating from northeast Europe (during the

earlier period of the campaign), and oce-

anic air masses originating from the Atlantic

ocean (during the later period). The first

period was marked by an intense contamina-

tion episode. Measurements of natural

atmospheric radioactivity showed that

these meteorological conditions induced

significant variations of radionuclide activ-

ity levels in aerosols (210Po, 212Po, 214Po, 210Pb, 212Pb, 214Pb, 7Be), without observable differ-

ences between different sites. The highest

radioactivity levels as a function of aerosol

particle size were measured for a mean

particle diameter of less than 0.4 µm, i.e.

fine particles. Relatively high 3H activity

concentrations (ranging from 2 to 8 Bq.l-1)

were measured in atmospheric water vapor

at the Puy-de-Dôme site. An analysis of

"retrotrajectories" showed that the air

masses originated from northeast of the

measurement site.

The technique implemented demonstrated

the possibility of using 3H as an atmo-

spheric tracer over long distances.

Similar activity concentrations of 137Cs (0.5

mBq.l-1) were measured in the rain and cloud

water collected at the Puy-de-Dôme site.

Aerosols within the clouds were collected

in water droplets. Even in the absence of

rain, the humidification of soils and plants

touched by droplets suspended in clouds

results in hidden depositions associated with

quantities of water too low to be measured by

rain gauges.

This type of deposition is generally not

explicitly considered in models. In mountain

ranges regularly touched by clouds, taking

these radionuclide depositions into account

explains the excess activity concentrations

in soil, as compared to depositions induced

by rainfall.

Figure 2 Atmospheric water vapor and cloud water collectors.

Atmospheric water vapor collectorCloud water collector



1.6

Christophe DEBAYLE, Laure TARDIEU

Environmental Radiation Protection Watch Laboratory

The ARGOS experimental platform

installed in Le Vésinet, near Paris, has a

twofold objective: to assess the possibility

of using the PANORAMA standard supervi-

sion software package to centralise all data

collected by automated environmental

radioactivity sensor systems throughout

France, and to conduct a series of metro-

logical tests on off-the-shelf sensors with

a view to selecting future sensors for IRSN’s

Téléray ambient gamma radioactivity

monitoring network. The first objective was

achieved in 2007. Initially designed for the

supervision and control of industrial auto-

mated systems, the PANORAMA software

package has been successfully used to

"interface" a set of ambient gamma dose

rate measurement probes and meteoro-

logical sensors by defining a "communica-

tion standard" between remote devices and

the centralizing server.

IMPlEMENTATION OF THE ARgOS ExPERIMENTAl PlATFORM for the assessment and characterization of IRSN environmental radioactivity measurement instruments

30/07/0814:00

30/07/0814:30

30/07/0815:00

30/07/0815:30

30/07/0816:00

30/07/0816:30

30/07/0817:00

0

300

250

200

150

100

50

Dose rate (nSv/h)

LB 6360_6050 IGS-510 A RSS-131

Figure 1 Dose rate values measured by three probes subjected to several successive exposures to a source of barium-133 during an experiment using the source masking/exposure system.



The meteorological tests corresponding

to the second objective were initiated in

July 2008. These tests aimed to compare

the responses of different sensors during

controlled exposure to different radioactive

sources: barium-133, cesium-137, cobalt-60,

europium-152, europium-154. These radio-

nuclides were chosen to cover the entire

gamma energy spectrum.

Two different experimental systems were

installed for this purpose:

A first experimental system placed at the

center of a two-meter radius circle on which

are arranged a series of dose rate measure-

ment probes, used to expose and mask

radioactive sources behind a lead-coated

vessel so as to simulate fluctuations of the

ambient gamma dose rate. This type of

experiment will provide synchronous data

on the responses of the various probes to

slight variations in dose rate, similar to those

that may occur during the passage of a

radioactive cloud.

A second experimental system composed

of a 25-meter automated linear rail, used

to perform perfectly reproducible displace-

ments of radioactive sources. In addition to

simulating the more or less furtive passage

of a radioactive source, this type of exper-

iment can be used to determine the angu-

lar response of sensors. Moreover, given the

perfect control of rail velocity (and therefore

of exposure time), it will also be possible to

assess the meteorological limits of the

devices tested.

Tests were scheduled to continue until late

2008. The results obtained will provide valuable

technical data for the selection of replacement

probes for the Téléray network.

The ARGOS experimental platform will

subsequently be used to improve control of

probe parameters (integration time, data

smoothing algorithms, etc.) and to test

future detectors as they are released on the

market.

This type of experimental platform could

perfectly be used by in-house or outside

partners to conduct specific measurement

campaigns (mobile equipment, assistance

operations, etc.).

Figure 2 ARGOS experimental platform.


Introduction

international radon concentration mapping campaigns

Since the late 1970’s, a large number of measurements of radon

concentrations in dwellings have been performed in Europe, the

United States and Canada. A relation between geology and radon

activity in buildings has been observed since the early 1980’s. Studies

conducted for the past 20 years have aimed to establish methods

allowing optimal control of potential health hazards associated

with the presence of radon in dwellings.

One of the approaches used consists of mapping the geographical

areas where high radon concentrations in buildings are most likely

to be encountered. The "radon concentration maps" obtained serve

a twofold purpose: improved targeting of measurement campaigns

in existing buildings potentially exhibiting radon concentrations

exceeding fixed threshold values (i.e. values considered by public

authorities as requiring the implementation of corrective actions),

and identification of areas where preventive measures could be

taken in future buildings.

This research is based on the following information: measurements

of radon activity concentration in dwellings, in soils or in the

atmosphere, measurements of radon flux at the soil surface, local

geological and pedological characteristics, and possibly the archi-

tectural characteristics of buildings. The parameters used are deter-

MAPPINg PRIORITY zONES for radon risk control

1. 7

Géraldine IELSCH, Edward Marc CUSHINGRisk Assessments on Naturally-Occurring Radiation Unit

Philippe COMBESGeoter

Radon is a natural radioactive gas present throughout the Earth’s surface. Radon-222, produced through the

decay of radium-226, itself a descendant of uranium-238 (naturally present in rocks and subsoils), is the radon

isotope the most frequently encountered in the environment, due to its relatively long half-life (3.8 days). Radon

flux at the soil surface varies according to different parameters, mainly associated with the properties of the

rocks or soils that produced the gas, through which it can more or less easily migrate to the atmosphere through

various physical processes. Radon may accumulate in the confined air within buildings, where humans spend

most of their time. The presence of this gas, acknowledged as a pulmonary carcinogen since 1988, can induce

exposure via inhalation, thereby posing a health risk. Among the strategies adopted to control this risk, one

particular step consists of defining zones which, due to their natural characteristics (geological characteristics in

particular), are most likely to exhibit significant radon concentrations in buildings. This is achieved by establishing

a "radon concentration map".


1. 7

representativity of the variability of the French subsoil (Burgundy,

Brittany, Massif Central, Pyrenees, Languedoc). This comparison led to

the validation of the approach [Ielsch et al, 2002; Ielsch, 2003; Ielsch

and Cuney, 2004].

Current request from the French nuclear safety

authority: update priority zones

Current regulations regarding the control of potential health hazards

associated with radon exposure in public sites require that certain

organizations conduct radon concentration measurements in dwell-

ings in 31 regional districts classified as priority zones on the basis

of the results of the national measurement campaign conducted

between 1982 and 2000 by IPSN and DGS(2).

Experience acquired through the application of these regulations

has served to identify the limits to defining priority zones based

on administrative borders (i.e. those of the 31 départements (local

government administrative entity) considered). Due to the signifi-

cant heterogeneity that may be present inside a given département,

certain areas with a low potential for high radon concentrations in

buildings are subject to screening requirements, whereas other areas

with a much higher risk potential are not subject to such require-

ments because they are not located within one of the 31 départe-

ments considered as priority zones. Faced with this situation, the

French nuclear safety authority (ASN) has asked IRSN to present a

summary of the different "radon mapping" methods used locally

in France and to propose a general method to divide the country

into zones classified according to their "radon potential" [Ielsch,

2005]. The method proposed by IRSN consists of determining the

capacity of geological formations to produce radon and to facilitate

its transfer to the surface before it decays.

Application of this mapping method to a test zone located in Burgundy

(equivalent to three regional districts) showed that the results obtained

were for the most part consistent with the results of measurements

of radon activity concentration in dwellings available for the area [Ielsch,

2007]. The zones obtained using this method provided greater accu-

racy than areas based on département borders and appeared appro-

priate for determining which municipalities would most likely be

affected by radon exposure. Based on these encouraging results, the

ASN asked IRSN to apply the method to the entire country, redefin-

ing the borders of priority zones so that they would be approxi-

mately the same size as the current départements. Mapping of radon

exhalation potential in France began in March 2008 and should be

mined either directly (in situ or in the laboratory) or indirectly via

tools such as geological maps, pedological maps, radiometric maps,

etc.

These past years, significant studies have been conducted in sev-

eral countries in order to establish radon concentration maps and

improve current knowledge of domestic exposure to this gas. Different

methods have been developed for this purpose [Dubois, 2005; Ielsch,

2005; Miles and Appleton, 2005; Bossew and Dubois, 2006; Barnet

and Fojtíková, 2006; Appleton, 2007; Kemski et al, 2008; Ielsch,

2008].

In order to coordinate European efforts in this area of research, in

August 2008 the European Commission established a working group

devoted to mapping radon concentrations throughout Europe using

a common method based on geological criteria. The countries

represented in this working group are the United Kingdom, Germany,

Belgium, France, the Czech Republic, Spain, Sweden, Norway, and

Austria.

Previous iRSN research in this field

The main difficulty encountered in controlling the potential health

hazards associated with the presence of radon in buildings in France

is due to the significant variability of radon exposure throughout

the country, particularly on account of its geological diversity (i.e.

ancient mountain ranges rich in granite and metamorphic forma-

tions, and younger mountain ranges mostly composed of sedimen-

tation and sedimentary basins). This variability needs to be taken

into account in establishing a radon exposure risk control policy,

which requires the development and implementation of adequate

tools and resources.

For many years now, IRSN teams have been engaged in research

aiming to develop and validate a method for mapping the radon

exhalation potential(1) throughout the French territory. The goal of

this research is not to directly assess the health hazards associated

with radon, but to provide qualitative indications on the radon

emission potential at the soil surface. Specific studies have been

conducted at IRSN since 1994 [Demongeot, 1997], particularly

within the framework of the Environment and Human Health

Program implemented in 1997 by the French Ministry for Health

and the Ministry for the Environment [Ielsch and Haristoy, 2001;

Ielsch et al, 2001, 2002]. These studies were pursued in 2002, lead-

ing to the development of a method to produce a regional-scale

predictive map of radon exhalation potential at the soil surface,

based on local geological and pedological parameters. The predictive

results obtained using this method have been compared with the

results of in situ measurements of radon flux at the soil surface in

various areas selected for their different geological context and their

(1) Radon exhalation at the soil surface results from the production of radon in rocks and its subsequent transport through rocks and soils to the surface.

(2) IPSN: Institute for Nuclear Protection and Safety; DGS: Directorate General for Health.



1. 7

uranium content, e.g. presence of geological formations rich in

organic matter (black shale, brown coal, etc.).

The data used consists of the geological map of France at a scale

of 1:1,000,000 [Chantraine et al, 2003], information obtained from

more accurate geological maps at a scale of 1:50,000 and 1:250,000,

chemical rock analysis results compiled in various databases con-

taining the results of approximately 5,000 spot analyses (IRSN,

BRGM, CREGU-G2R(3)), available geochemical data concerning

similar lithologies in France or abroad (bibliographic research results),

inventory of French uranium mining sites (MIMAUSA, IRSN), and

the Geoderis database(4).

This assessment was performed in several successive steps:

compilation of data used to determine the uranium content for

each geological formation;

grouping and classification of geological formations as a function

of lithology, and classification of lithologies according to measured

or estimated uranium content (leading to the establishment of a

map of Source Potential 1 categories);

identification of local characteristics possibly inducing an increase

of the Source Potential 1 level of a given geological formation

(leading to the establishment of a map of Source Potential 2

ca tegories).

Classification and mapping of the potential capacity of

geological formations to produce radon

Grouping and classification of geological formations as a function

of lithology and possible uranium content (Source Potential 1).

The objective was to assign an average uranium content class to

French geological formations at a scale of 1:1,000,000. This was done

by estimating the uranium content of the geological formations

based on available geochemical analysis results and lithological and

geochemical data obtained from the geological map of France or by

comparison with similar known lithologies in other regions. First of

all, the geochemical analysis results were processed to determine

the average uranium contents of the geological formations. Based

on the lithological and geochemical data and the definition of value

classes (Table 1), a probable uranium content was then assigned to

geological formations for which no measured data is available. The

classification established on the basis of uranium concentration

estimates grouped into four classes was used to determine and map

the potential capacity of the geological formations to produce radon.

The resulting map of Source Potential 1 categories was subsequent-

completed in late 2009. The objective is to provide maps of "radon

potential" for the entire country, covering both administrative regions

and départements, with an accuracy equivalent to that of the

1:1,000,000-scale geological map of France.

Method

It is recalled that the method adopted does not aim to determine

"radon potential" based on the results of measurements of radon

activity concentration in buildings, but rather to assess the radon

potential of soils (which are the main source of radon in

buildings).

This method consists of taking into account the main parameters

influencing radon production in the subsoil and radon transport to the

soil surface. The parameters considered are not exhaustive, but they

allow for a homogeneous application of the method throughout France,

using existing data. The method implemented is based on the compila-

tion and use of geological data available for each region in maps,

databases, research results, etc. It does not require additional investiga-

tion or on-site data acquisition. All of the information used is inte-

grated into a geographic information system so as to cross-reference

geological parameters and thereby divide the country into zones with

an equivalent radon potential.

The method implemented comprises three steps. The first step

consists of classifying geological formations according to their mea-

sured or estimated uranium content so as to define the potential

capacity of soils to produce radon (which is derived from uranium).

The second step consists of refining the resulting map by taking into

account, as far as possible, the factors facilitating radon transport

through rocks and potentially favoring radon exhalation at the soil

surface. The third step consists of establishing a final classification

into zones, based on the analysis of the various parameters considered,

in order to produce a map of the radon potential of soils.

First step: assessment of the radon source potential of

geological units

Selected criteria and data

The criteria chosen to determine the potential capacity of soils to

produce radon consist of the following: lithology (rock type), results

of direct uranium analyses in rock samples, results of uranium

analyses for similar lithologies in sites other than those considered,

results of radiometric measurements (ambient radioactivity mea-

surements using mobile terrestrial or airborne gamma radiation

detection systems), uranium mining indicators, proximity of old

uranium mines, local characteristics possibly inducing a higher

(3) Joint research unit of CNRS and Henri Poincaré University (Nancy).

(4) Public interest group authorized to intervene for all issues related to inter-rupted mining operations, at the request of relevant administrative authori-ties (participants include BRGM and Ineris).


1. 7

In addition, the presence of uranium prospecting sites, uranium mines,

coal mines (hard coal, brown coal, etc.) and ore beds were also used

to locate this type of geological formation. The Source Potential 1

category of these formations was then increased by one.

The resulting map of Source Potential 2 categories taking into account

Source Potential 1 categories and specific local characteristics com-

prised five categories: low, low to average, average, high, very high

(Table 2).

Second step: determination and consideration of

aggravating factors possibly favoring radon exhalation

at the soil surface

Selected criteria

A number of "aggravating" factors were defined, i.e. factors poten-

tially facilitating radon transport to the surface. These aggravating

factors locally increase the radon release potential of a given zone.

They can be of natural or anthropic origin:

existence of major or active faults, with influence zones;

mining sites or operations with associated underground structures

(shafts, galleries, etc) potentially causing soil destabilization;

main hydrothermal sites;

natural underground cavities in karstic formations.

The following data was used to identify these factors: 1:1,000,000-

scale geological map of France (BRGM, revision 6, 2003), information

obtained from more accurate geological maps (BRGM), inventory

of French uranium mining sites (MIMAUSA(5), IRSN report prepared

for the French Ministry for Ecology), the Geoderis database,

1:1,000,000-scale map of mineral and thermal water resources in

France (BRGM, 2004), 1:1,000,000-scale map of seismic and fault

zones (IRSN, Geoter).

Classification and mapping of "radon potential"

Faults

In addition to the "major faults" indicated on the geological map of

France at a scale of 1:1,000,000, classification also included tectonic

structures not indicated as major faults but exhibiting "recent" seismic

activity (Quaternary or even Plio-Quaternary seismic activity). The

seismic activity of faults is a significant indicator, since open fractures

and more permeable brecciated facies facilitate the circulation of radon.

It is also useful to take into account large-scale accidents recognized

by their geophysical characteristics, since they may be related to surface

faults, thereby favoring radon transfer to the surface.

ly refined by taking into account local characteristics potentially

inducing an increase of this capacity.

Identification and consideration of local characteristics potentially

increasing the Source Potential 1 level of a given geological formation:

determination of Source Potential 2.

The estimated uranium content of the geological formations (deter-

mined during the first step) was readjusted based on the identifica-

tion of specific local characteristics.

First of all, certain specific regional geological formations (particu-

larly sedimentary deposits) may exhibit a higher uranium content

than the average value generally observed for a given lithology.

Geological formations such as these were identified on the

1:1,000,000-scale geological map based on lithology (coal, arkose,

etc.) and/or stratigraphic age (Permian, Carboniferous, etc.). However,

certain formations of this type have not been mapped to a scale of

1:1,000,000. More precise maps must therefore be consulted to

delimit these formations.

LithologyAverage u content (ppm)

Corresponding Source Potential 1 category

Basic and ultrabasic plutonic and volcanic

rocks,amphibolites,

carbonated formations

≤ 2 Low

Detritic sedimentary formations and

paragneiss formations (schists, except

bituminous schists)

≤ 4 - 5Low to average (heterogeneous)

Granitoids and metagranitoids with low

uranium content (granodiorites, granites,

peraluminous leucogranites, calco-alkaline granitoids,

orthogneiss), volcanic rocks with equivalent chemical affinity, and

other specific lithologies

≤ 8 Average

Peraluminous granites and leucogranites,

subalkaline granitoids, peralkaline Corsican

granites, volcanic rocks with equivalent chemical

affinity and other specific lithologies

≥ 8 High to very high

Table 1 Average uranium contents of geological formations and corresponding Source Potential 1 categories.

(5) MIMAUSA: Impact analysis database for French uranium mining sites.



1. 7

When deep waters loaded with radon come into contact with the

open atmosphere, they release the radon into the atmosphere.

Resurgence and exsurgence locations were obtained from a database

of natural underground cavities, and thermal source locations were

obtained from the 1:1,000,000-scale map indicating mineral and

thermal water sources in France (BRGM, Risler et al, 2004).

Only the main sites affected by thermomineral sources were con-

sidered. The aggravating factor was applied directly below these

sites, with an uncertainty "buffer area" estimated at 500 m around

each site. The radon potential of the corresponding zone was

increased accordingly (Table 3 and Figure 1).

Geological formations with karstic characteristics

A karst is a more or less open space where radon can concentrate

and circulate. Natural karstic cavities form networks, sometimes

quite extensive, in a large number of carbonated formations through-

out France. The area covered by these networks is often difficult to

estimate, but the lithology and conditions under which they devel-

op are well known. The national database of underground cavities

(BRGM) provides data at the surface above the spot where a cavity is

located, whereas the associated network may reach out over a long

distance from this point. The points identified in the database represent

orifices and centers of cavities or networks. Far-reaching cavities or

networks are therefore only partially represented by these points.

Limitations related to the heterogeneous nature of the nationwide

information provided in the BRGM database (inventory in progress)

and the difficulty of selecting only supposedly karstic formations from

the 1:1,000,000-scale geological map of France make it difficult to

take into account this aggravating factor in a uniform manner across

France. As a result, the presence of karsts was not taken into consid-

eration in the mapping method.

Faults were therefore considered, in principle, as aggravating factors,

with a standard estimated influence zone of 500 m on both sides

of the fault (this standard estimate takes into account uncertainty

on fault position accuracy at a scale of 1:1,000,000, as well as the

fact that certain major geophysical anomalies are actually extensive

multiple "fault" zones).

As a result, the presence of a fault in a given geological formation

led the intersection zone (i.e. where the influence zone of the fault

intersects the geological formation) to be classified as a higher

radon potential category (Table 3 and Figure 1).

Open-air shafts and galleries

The Geoderis mine database was used to take into account dis-

turbances related to mining activities and the subsequent under-

ground structures. These anthropic underground structures induce

fissures or fractures in geological formations and act like collectors

that drain radon and accelerate its transfer to the surface.

The aggravating effect of underground structures was considered

as being concentrated directly above their location (by projecting

their footprint to the surface). An uncertainty zone, or "buffer" zone,

estimated at 500 m, was applied around these sites, and a higher

radon potential was assigned to the area where the aggravating

factor intersects the corresponding geological formations (Table 3

and Figure 1).

Thermomineral sources

Thermal sources, resurgences and exsurgences may constitute

sources of radon emission in that they form drains that collect

radon (in the form of gas dissolved in water) and facilitate its

transfer from the subsoil to the surface.

Source Potential 2

Aggravating factor

Radon potential of intersection zone

Low

+ 1

Low to average

Low to average Average

Average High

HighVery high

Very high

Source Potential 2

Low

Low to average (heterogeneous)

Average

High

Very high

Table 2 Classification of Source Potential 2 of a geological formation.

Table 3 Impact of an aggravating factor on the radon potential of a geological formation.


1. 7

Map of radon source potential

Mapping factors that facilitate radon transport

a. Polygonal factor (e.g. fault)

2

Mapping radon source term in subsoil: estimate of probable uranium content of rocks1

Classification of radon potential3

Geological map of France

(1:1,000,000 scale)

Geochemical database

Mines database

Available literature, more accurate geological maps

Low

Low to average

Average

High

Very high

b. Spot factor (e.g. open-air shafts and galleries)

Aggravating factor applied along fault (“buffer zone” estimated at 500 m)Incrementation of radon potential in intersection zone Classification into five categories

Map of radon source potential

(based on uranium content of geological

formations)

Use of simplified classification for final map of radon potential of geological formations

Aggravating factor applied to site (“buffer zone” estimated at 500 m)Incrementation of radon potential in intersection zone Classification into five categories

Low

Average

High

Radon potential: Steps 1 and 2 Final simplified radon potential

Low

Low to average

Average

High

Very high

Figure 1 Main steps of the method used to map the radon potential of geological formations.



1. 7

The Pays de la Loire region mostly consists of Armorican massif

terrains (crystalophylian formations) composed of Cadomian and

Hercynian granites and Proterozoic and Paleozoic metasediments

(volcanites and sediments) covered in the eastern part by Mesozoic

and locally Cenozoic transgressive sedimentary sequences of the

Paris basin. A thin strip in the southeastern part is covered by

sedimentary sequences of the Aquitaine basin.

This region is cut across by a major WNW-ESE structural accident,

the South Armorican shear zone, which divides the Armorican

massif into two blocks, each organized into distinct units with

specific geodynamic and structural characteristics.

A simplified geological map of the region is shown in Figure 2.

Grouping and classification of geological formations as a

function of lithology and estimated uranium content ("source

potential")

The available geochemical analysis results and known uranium

contents were compiled for the various geological formations in

the region and used to assign a range of probable uranium content

values to the formations so as to classify them according to these

values. This led to the establishment of the map of Source Potential 1

categories shown in Figure 3.

Moreover, upon examining the chemical characteristics of the

geological formations of the Pays de la Loire region and the data-

bases available in the "literature", specific series were identified

exhibiting higher uranium content values than those generally

observed in these lithologies. They consist of sedimentary and

volcanosedimentary series rich in Carboniferous coal and Ordovician

Armorican sandstone.

In addition, the inventory of uranium or coal mining sites identified

certain uraniferous geological formations (Figure 4). The uranium

content of these specific formations was readjusted to establish

the map of Source Potential 2 categories (Figure 5).

Determining and taking into account aggravating

factors that could favor radon exhalation at the soil

surface

All factors potentially increasing radon exhalation, identified based

on available data, are reported in the map shown in Figure 6: major

and active faults, underground mining sites, spoil heaps, thermo-

mineral sources.

Third step: Final classification and mapping of

geological units according to radon potential

The last step was based on cross-referencing the various informa-

tion gathered during the previous steps:

map of Source Potential 2 categories associated with the uranium

content of geological formations;

map of aggravating factors potentially facilitating radon

transfer.

This information was processed to obtain a final map of the radon

potential of geological units, taking into account the three categories

resulting from the simplified classification previously adopted at

the end of Step 2. The general approach is summarized in Figure 1.

First results: example of the Pays de la loire region

Classification of geological formations according to

"source potential"

Geological context of the Pays de la Loire region

Sedimentary basin

of Aquitaine

South-Armorican

shear zone

Sedimentary

basin of Paris

40 km

Tertiary formationsCretaceous formations

Quaternary formations

Jurassic formations

Hydrography

Volcanic rock and Brioverian sediments

Metamorphic formations

Volcanic rock and Palaeozoic sediments

Hercynian granitoids

Faults

Figure 2 Simplified geological map of the Pays de la Loire region.


The major faults primarily affect the bedrock formations in the

southern half of the region and are mainly associated with the

South Armorican shear zone. Mining sites including underground

and open-air structures were identified. They consist of uranium,

coal, iron and polymetal ore mines.

Three thermal sources were identified in the Pays de la Loire region

based on the 1:1,000,000-scale map of mineral and thermal water

sources in France.

"Radon potential" map of the Pays de la Loire region

The map obtained for the Pays de la Loire region is shown in Figure 7.

In this region, the radon potential of geological formations is

highly variable and heterogeneous from one département to

another. In current regulations, the départements in this region are

not defined as priority zones. However, the map indicates a high

radon potential in part of the territory contained within these areas,

particularly in Loire-Atlantique, Vendée and Maine-et-Loire.

In Mayenne the radon potential is mainly low to average, whereas

in Sarthe it is primarily low.

It is interesting to note that the preliminary comparison between

the radon potential map obtained using this method and the

available measurement results of radon activity concentration in

1. 7

Le Mans

Mamers

La Flèche

Laval

Segré

Ancenis

NantesSaint-Nazaire

Angers

Cholet

La Roche-sur-Yon

Fontenay-le-Comte

Les Sables-d'Olonne

Saumur

Châteaubriant

Mayenne

Château-Gontier

40 km

Low to averageAverage

Low

High to very high

RoadsHydrography

Source Potential 1

Le Mans

Mamers

La Flèche

Laval

Ancenis

NantesSaint-Nazaire

Angers

Cholet

La Roche-sur-Yon

Fontenay-le-ComteLes Sables-d'Olonne

Saumur

Mayenne

SegréChâteaubriant

Château-Gontier

RoadsHydrography

40 km

Mining sites: Hard coal (Geoderis database)Mining sites: Uranium (Geoderis database)Old uranium mining sites (MIMAUSA database)

Additional local factors

Sandstones, conglomerates, coals, tuffites (Carboniferous)Sandstones, schists, coals, conglomerates (Carboniferous)Wackestones, schists, sandstones, coals (Carboniferous)Armorican sandstones (Arenigian, Ordovician)

Additional source formations

Le Mans

Mamers

La Flèche

Laval

Ancenis

NantesSaint-Nazaire

Angers

Cholet

La Roche-sur-Yon

Fontenay-le-Comte

Les Sables-d'Olonne

Saumur

Mayenne


Château-Gontier

40 km

Low to averageAverage

Low

HighVery high

RoadsHydrography

Source Potential 2

Figure 3 Map of Source Potential 1 categories of the Pays de la Loire region.

Figure 4 Map of the specific local characteristics used to identify geological formations in the Pays de la Loire region potentially exhibiting a higher uranium content than the average value observed in equivalent lithologies.

Figure 5 Map of Source Potential 2 categories of the Pays de la Loire region.



Implementation of this method may lead to a more accurate

representation of the zones in question than an approach based

on administrative maps, providing a more adequate solution to

determining which municipalities are most affected by the

potential health hazards associated with radon exposure, based

on a more objective view of the variability of radon emission.

The resulting map could lead to reorganizing administrative

boundaries to achieve a better definition of priority zones.

The representativity of the map established using this method

obviously has certain limitations, some of which are inherent to

the accuracy of the source of information used (definition of the

geological map used). Working at a scale of 1:1,000,000 does

not make it possible to make a distinction between facies varia-

tions within a given geological unit, nor to take into account

geological units of limited size (less than one kilometer), such as

veins, inclusions, surface formations, etc. The resulting predic-

tive maps cannot serve to identify general trends in "radon

potential" without substantiating this information by measur-

ing radon concentration directly in the environment or in

buildings, in order to detect anomalies such as high radon

activity concentration in an environment with a low radon

potential, and vice versa.

1. 7

dwellings within a test zone located in Burgundy [Ielsch, 2007]

was conclusive for the most part. There are plans to conduct a

similar comparison on a nationwide scale once the map of radon

potential has been completed throughout France.

Conclusion

Mapping the potential capacity of geological formations to

produce radon, currently being conducted by IRSN at the

request of the ASN, aims to produce maps based on regional

and local administrative areas (96 départements) covering

mainland France, to an accuracy equivalent to that of the

1:1,000,000-scale geological map of the country. All of these

regions will be covered by the end of 2009.

The method implemented aims to assess the radon potential of

soils, which constitute the main source of radon exposure in

buildings. It is based on the compilation and use of geological

data on each region available from maps, databases, research

results, etc. and does not require additional on-site investiga-

tion. The process has been designed to cover the entire territory

of France in a homogeneous approach.

La Roche-sur-Yon

Guenrouët

Le Breil-sur-Mérize

Le Mans

Mamers

La Flèche

Laval

Ancenis

NantesSaint-Nazaire

Angers

Cholet

Fontenay-le-Comte

Les Sables-d'Olonne

Saumur

Mayenne


Château-Gontier

40 km

Spoil heapsThermomineral sources

Open-air shafts and galleries

Faults

RoadsHydrography

Aggravating cofactors

Le Mans

Mamers

La Flèche

Laval

Ancenis

NantesSaint-Nazaire

Angers

Cholet

La Roche-sur-Yon

Fontenay-le-Comte

Les Sables-d'Olonne

Saumur

Mayenne


Château-Gontier

40 km

AverageHigh

Low

RoadsHydrography

Radon potential

Figure 6 Map of aggravating factors possibly inducing an increase

of radon exhalation in the Pays de la Loire region.Figure 7 Final map of radon potential in the Pays de la Loire

region.


1. 7

The request issued by the French nuclear safety authority is part

of the interministerial action plan for the control of potential

health hazards associated with radon exposure, which aims to

meet the objectives of the national health and environment plan,

and respond to needs expressed by several local organizations.

Moreover, the maps obtained only provide information on the

main source of radon exposure in buildings (i.e. soils) and can-

not be used to assess the radon concentration in a building. To

do this, it is necessary to take into account the specific charac-

teristics of the building, the lifestyle of its occupants, radon

transfer phenomena at the soil/building interface and within the

building itself, etc. Only a direct measurement of the radon

concentration in the atmosphere within a building can ensure a

reliable result.



1. 7

References

J.-D. Appleton (2007). Radon: Sources, health risks, and hazard mapping. Ambio 36(1) : 85-89.

I. Barnet et I. Fojtíková (2006). Radon index of bedrock and its influence on strategy of detection of radon risk dwellings in the Czech Republic. Zprávy o geologických výzkumech v roce 2005, 128-132,CGS, Praha. ISBN 80-7075-667-5.

P. Bossew, G. Dubois (2006). From Babel to the Round Table of Camelot: on setting up a common language and objective for European radon risk mapping. Part II. Harmonization and standardization of radon data and maps. In: Proceedings of the 8th International Workshop on the geological aspect of radon risk mapping, p. 88-97, I. Barnet, M. Neznal, P. Pacherova (Eds). 26-30 September 2006, Prague, Czech Republic.

Chantraine et al., (2003). Carte géologique de la France au 1/1 000 000e, 6e édition révisée, BRGM Orléans.

S. Demongeot (1997). Recherche des différents paramètres caractérisant le potentiel d’exhalation en radon des sols. Thèse de doctorat, université de Franche-Comté, 253 p.

G. Dubois (2005). An overview of radon surveys in Europe. EUR 21892 EN, EC. 168 p.

G. Dubois, P. Bossew (2006). A European Atlas of Natural Radiations including harmonized radon maps of the European Union. What do we have, what do we know, quo vadimus? In: Proceedings of the Terzo Convegnio Nazionale. Controllo ambientale degli agenti fisici: dal monitoraggio alle azioni di risanamento e bonifica, 7-9 June 2006, Biella, Italy. ARPA Piemonte, ISBN-10: 88-7479-099-3.

G. Dubois, P. Bossew (2006). From Babel to the Round Table of Camelot: on setting up a common language and objective for European radon risk mapping. Part I. Radon risk maps, different maps for different purposes. In: Proceedings of the 8th International Workshop on the geological aspect of radon risk mapping, p. 39-48, I. Barnet, M. Neznal, P. Pacherova (Eds). 26-30 September 2006, Prague, Czech Republic.

G. Ielsch (2003). Méthodologie de cartographie prédictive du potentiel d’exhalation du radon à la surface des sols : bilan des projets de recherche et validation complémentaire. Rapport IRSN DEI/SARG n° 03-02, octobre 2003.

G. Ielsch (2005). La cartographie radon des territoires – Synthèse des approches utilisées en France et proposition d’éléments méthodologiques généraux. Rapport IRSN DEI/SARG/2005-06, mars 2005.

G. Ielsch (2007). Définition des zones prioritaires pour la gestion du risque lié au radon dans les bâtiments – Application de la méthode dite indirecte aux trois départements de Bourgogne. Rapport IRSN DEI/SARG/2007-026, mai 2007.

G. Ielsch (2008). Mapping of the geogenic radon potential in France to improve radon risk management: methodology and first application to region Bourgogne. The 9th International Workshop on the Geological Aspects of Radon Risk Mapping (12-13st August 2008), into the 33rd International Geological Congress; Oslo, Norway (6-14th August 2008).

G. Ielsch, M. Cuney (2004). Cartographie prédictive du potentiel d’exhalation du radon 222 à la surface des sols : exemple d’application dans le massif armoricain. Environnement, Risque et Santé, Vol 3, n° 1, janvier-février 2004, p. 35-43.

G. Ielsch, C. Ferry, G. Tymen, M.-C. Robé (2002). Study of a predictive methodology for quantification and mapping of the radon 222 exhalation rate. Journal of Environmental Radioactivity, 63(1) : 15-33.

G. Ielsch, D. Haristoy (2001). Mise au point d’une méthodologie permettant l’élaboration d’un outil cartographique prédictif en vue d’identifier les zones potentiellement exposées à de fortes concentrations de radon (2 volumes). Rapport IPSN-BRGM Réf. IPSN/DPRE/SERGD RT 01-05.

G. Ielsch, D. Thiéblemont, V. Labed, P. Richon, G. Tymen, C. Ferry, M.-C. Robé, J.-C. Baubron, F. Béchennec (2001). Radon (222Rn) level variations on a regional scale: influence of the basement trace elements (U, Th) geochemistry on radon exhalation rates. Journal of Environmental Radioactivity, 53(1) : 75-90.

J. Kemski, R. Klingel, A. Siehl, M. Valdivia-Manchego (2008). From radon hazard to risk prediction-based on geological maps, soil gas and indoor measurements in Germany. Environ Geol, DOI 10.1007/s00254-008-1226-z.

J.-C.-H. Miles, J.-D. Appleton (2005). Mapping variation in radon potential both between and within geological units. Radiol. Prot. 25 257-276.

J.-J. Risler et al., (2004). Carte des eaux minérales et thermales de France au 1/1 000 000e (BRGM).



(1) Study funded by the French environmental and energy control agency (Ademe).

Vanessa PARACHEContinental and Marine

Radioecological Studies Laboratory

Projects such as IRSN’s SENSIB project

(on radioecological sensitivity), EDF’s

CONCERT project (for the elimination of

conservatism in the assessment of environ-

mental and health risks) and CEA’s MRISQ

project (for risk control and environmental

impact assessment) share the common

objective of improving assessment of the

impact of radioactive, non-radioactive,

chronic or accidental release of contami-

nants on human health and the environ-

ment, through better consideration of land

use characteristics. To achieve this objective,

up-to-date and accurate data must be col-

lected on land use characteristics, particu-

larly those significantly influencing risk

assessment results.

In 2007, IRSN, EDF and CEA established

a scientific collaboration project that set

out to acquire information on land use

around French nuclear sites, by means of a

geographic information system. From an

environmental perspective, the term "land

use" mainly refers to the agricultural use

of soil and the use of water resources. After

examining existing spatial databases, it

appeared that the information contained

therein was limited, particularly due to

inaccurate data aggregation, statistical

confidentiality restrictions, and data status

and spatialization issues. The approach

adopted to overcome these difficulties

consisted of conducting field studies to

verify, supplement and improve existing

maps and databases. Supplementary data

on local food consumption and self-suffi-

cient farming practices was acquired using

a methodology based on the results

obtained around the Tricastin site in 2005

and further to the food consumption survey

conducted around the Chinon site in 2008(1).

The methodology and objectives are illus-

trated in Figure 1.

The data collected, which currently con-

cerns the Chooz, Tricastin and Chinon sites,

is useful in the context of a nuclear accident

(justification and implementation of coun-

ter-measures, etc.), and also in the context

of a more realistic assessment of the risks

associated with chronic release (character-

ization of reference groups and habits). An

example of the results obtained (Tricastin,

2008) is shown in Figure 2.

The results obtained will be used to build

a database of updated, realistic and region-

al information for the definition of popula-

tion exposure scenarios, and to assess the

impact of various types of agricultural land

use on the radioecological sensitivity of

soils.

MAPPINg lAND uSE AROuND NuClEAR SITES for assessment of radiological and health impact

1.8



15 %

8 %

4 %

8 %

5 %

19 %

16 %

23 %

2 %

3 %

a c

b

a

cb

Fruitvegetables

Meat Fruit

Leaf vegetables

Potatoes

Fish

Root vegetables

Eggs

Other fruit

Other (cheese, bread,

cereals, etc.)

Study on populations living near the Chinon-Avoine site

(initiated in 2008)

Data acquisition on Tablet PC, using ArcPad: creation,

identification and sizing of site parcels

Definition of a common approach for acquiring data on land use

around a nuclear site

Definition of a common approach for acquiring data on food

consumption around a nuclear site

Objective 1 Objective 2

Design of data compilation and georeferenced display tool

Objective 3

Processing of data collected on-site, using ArcGis 9.2

Comparison with existing national or regional data

Creation of geodatabase file (ArcGis 9.2) usable by partners

Average food consumption: 1,335 g/day/person

Figure 1 Mapping land use characteristics: methodology and objectives.

Figure 2 Update of agricultural land use data within a 5 km radius around the Tricastin site.

Autoroute du Soleil

5 km

D59

D13

N7

D59

Tricastin

Pierrelatte

Saint-Paul-Trois-Châteaux2 km

Rhône

Horse breeding

Aviculture

Pisciculture

Other

Agricultural

Pork breeding

Feedstock

Public

Buildings

CNPE 5 km radius

Livestock areas

Other

Arboriculture

Gardens

Fallow lands

Cipan crops

Industrial crops

Cereals

Agricultural areas

Oleaginous crops

Marshland

Transitional parcels

Oilseed crops

Forage crops

Unploughed land

Horticulture

Viticulture

Truffle crops

Tillable land

Proteaginous crops

PPAM



Marc-André GONZE, Christophe MOURLON, Laurent GARCIA-SANCHEZ, Séverine LE DIZES-MAUREL,

Christian TAMPONNET, Victor CHEN, Philippe CALMON

Environmental Modeling Laboratory

Emmanuel VIEILLETOILE, Fabien VERMOREL

EDF

Loïc PILORGET, Aurélien CAVALAN, Mathieu NOBLET

CRIL Technology

Lionel CHAILAN, Houda LABIDI, Matthieu JOBELIN

ASSYSTEM France

SYMBIOSE (simulating the impact of

radioactive environmental contamination

on human health) is a research and

development program, co-funded by EDF,

that aims to develop a simulation platform

to model radionucl ide transfers in

ecosystems and their dosimetric impact

on human health and the environment

(fauna and flora). Developed by IRSN’s

environmental modeling laboratory, this

tool sets out to support radiological risk

assessment studies on a wide range of

issues: normal and accident operating

conditions of nuclear facilities, dismantling

of nuclear facilities, safety assessment of

waste disposal facilities.

The latest version produced (SYMBIOSE

V1.1) was released in 2008 to interested

parties, including the following: the IRSN

Environment and Emergency Response

Division (Department for the Study of

Radionuclide Behavior in Ecosystems,

Emergency Response Organizat ion

Department), IRSN Division for the Safety

of Plants, Laboratories, Transport and Waste

(Irradiator, Accelerator and Radioactive

Waste Safety Department), IRSN Human

Radiation Protection Division (Radiation

Protection Analysis and Assessment

Department), the EDF Septen Division

(nuclear power plant operation under acci-

dent conditions) and EDF Ciden Division

(normal operation and decommissioning of

nuclear power plants).

Systems modelled

The ecosystems and processes modelled in

SYMBIOSE V1.1 are shown in Figure 1. They

consist of fluvial and marine systems, agri-

cultural systems, subsurface soils (non-sat-

urated zone), food chain, human activities,

and certain interface interactions. Interactions

with non-modelled systems (atmospheric

system with dry or wet deposition, liquid

effluent from nuclear facilities) are consid-

ered as input data. The main values calcu-

lated are activity level, biomass, flux, dose

rate, and the radiation dose received by

humans.

The range of radionuclides covered comprises

nearly 60 chemical elements, including

hydrogen, carbon and chlorine (elements for

which specific models have been developed).

Incorporation of radioactive daughter products

is scheduled for late 2009.

The resulting scope of study is modeled using

approximately 50 submodels (or modules).

Each module is devoted to a specific subsys-

tem (e.g. trophic fluvial chain, food collection

process) or a specific group of radionuclides

(such as 3H and 14C). The only difference

between two modules dealing with the same

subsystem may reside in the level of com-

plexity required to resolve mechanisms or

equations describing biological, physical, and

chemical processes (empirical or mechanis-

tic approaches, realistic or conservative

approaches) or in the range of space and

time scales covered.

SYMBIOSE: Simulation and modeling of radiological risks to human health and the environment

1.9



Time-based predictions of calculated values

are displayed by means of spatial display

graphics specific to a given module or shared

with other modules (e.g. computational grid,

one-dimensional network, collection of

points distributed in space). This modular

approach makes SYMBIOSE extremely

flexible, allowing simulations to be executed

with different levels of complexity,

depending on the objec tive.

Platform architecture

As shown in Figure 2, the SYMBIOSE plat-

form is built around four software compo-

nents:

a module library including a database of

reference values for all radioecological para-

meters involved in the system to be mod-

eled;

a simulator library;

a calculation engine;

a low-level component library based on a

functional breakdown of the modules.

A simulator is a computer code built by

interfacing pre-existing modules. The sys-

tem of equations underlying each simulator

is resolved in time and space by the calcula-

tion engine which contains various numer-

ical solvers used to handle systems with

complex temporal dynamics (e.g. coexis-

tence of slow and rapid or continuous and

discontinuous subsystems). The implemen-

tation of probabilistic methods (to take into

account uncertainty) and sensitivity analy-

sis methods is scheduled for late 2009.

This architecture is designed to accom-

modate a wide range of radioecological

activities, ranging from simple data queries

to module and simulator development and

studies based on turnkey simulators.

(ATMOSPHERIC SYSTEM)

External inhalation

External inhalation

External inhalation

External inhalation

HUMANS

Ingestion

Food crops and water collection

Food crops

Food crops

Water collection

FOOD CHAIN

Migration

VADOZE

(Deposition)

Irrigation for animal watering

AGRICULTURAL SYSTEM

Irrigation

Animal feeding

(RELEASE FROM NUCLEAR

FACILITIES)(Release)

MARINE SYSTEM

(Release)

(Deposition)

FLUVIAL SYSTEM

(Release)

Figure 1 Interaction matrix showing the components (diagonal squares) and component interactions (non-diagonal squares) modeled in SyMBIOSE V1.1. Non-modeled components, indicated in italics (atmospheric system, nuclear facility releases), nevertheless influence the system through interactions (releases, depositions and external doses due to plume).

Figure 2 Simplified diagram of SyMBIOSE V1.1 platform architecture.

Low-level component

library

…

Module library

(+ reference database)

Simulator library

Calculation engine

… …

Module Simulator



Denise STAMMOSEResearch on Geological Waste Repositories and

Near-surface Transfers Laboratory

1.10

In 2008, within the framework of the

PACEN program (an interdisciplinary

research program considering the final part

of the nuclear fuel cycle ), IRSN and CNRS

extended their partnership by creating the

TRASSE research group, a national research

group focusing on the transfer of radionu-

clides to soil, subsoil and ecosystems. The

creation of this national research group is

fully in line with IRSN research on nuclear

and radiological risks and strengthens the

position of CNRS as a major actor in

research on the final phases of the nucle-

ar fuel cycle, in compliance with French

Law no. 2006-739 of June 28, 2006 on the

sustainable management of radioactive

waste and materials.

The TRASSE research group aims to

accelerate the development of knowledge

and scientific expertise of the CNRS and

IRSN teams conducting research on the

mechanisms by which radionuclides are

transferred to the complex environment

formed by the surface of the Earth and the

biosphere, via bypassing containment bar-

riers at radioactive waste repositories or

disposal sites.

This national research group will also

contribute to a more widespread use of

relevant IRSN experimental sites (the

experimental underground station in

Tournemire and the T22 test platform in

the Chernobyl exclusion zone), by making

them more readily available to CNRS teams

within mixed research units including

CNRS researchers, engineers and trainees,

and doctoral students from major univer-

sities and institutes. It is funded in equal

amounts by IRSN and CNRS and may be

opened to other partners in the future.

CREATION OF THE TRASSE NATIONAl RESEARCH gROuP as part of the PACEN program (CNRS)

Figure 1 Experimental platform in Chernobyl.



A first request for project proposals was

issued in April 2008. The group’s scientific

committee evaluated the projects submit-

ted and selected nine of them based on

scientific and budgetary factors. These

projects are scheduled to run for two years.

Most of them are collaborative projects

conducted by CNRS and IRSN teams and

rely on the use of the two experimental

platforms shown in Figures 1 and 2. A sec-

ond request for project proposals was

scheduled to be issued by the end of the

second quarter of 2009.

Figure 2 Experimental station in Tournemire.



Pierre HURTEVENT, Chantal MADOZ-ESCANDE

Radioecology and Ecotoxicology Laboratory

A bibliographic compilation and assessment

of parameter values of foliar transfer in the

biosphere (leaf surface index and transloca-

tion coefficient characterizing the foliar

absorption and mobility of an element

within a plant), requested by the French

national agency for radioactive waste man-

agement (Andra) and conducted by IRSN

(participation in the working group devoted

to the revision of IAEA Technical Report Series

no. 364, EMRAS program, 2003-2007), has

led to the identification of significant knowl-

edge gaps regarding translocation coefficients,

particularly for chronic contamination situ-

ations resulting from spray irrigation through-

out the vegetative cycle of a crop. Most of

the data available concerns cesium and stron-

tium (Figure 1); while other radionuclides

have been investigated, the rare data available

is insufficient for determining reliable values.

This is the case for three radionuclides iden-

tified by Andra as "of interest" in long-term

high-level, long-lived waste disposal sce-

narios involving human exposure via direct

ingestion of vegetable products: 36Cl, 129I and 79Se.

Initiated in late 2007, the FORTRESS

project(1) aims to experimentally determine

the translocation factors of the three above-

mentioned radionuclides in main crop catego-

ries (four species). These experiments use leaf

sprinkling to simulate spray irrigation and

determine realistic translocation factor val-

ues. By focusing on the most influential

processes (chronic or sporadic contamination

and the main phenological phases) and using

an open-field approach, researchers expect

to obtain translocation factor values that can

be transposed to real conditions. In order to

FOlIAR TRANSFER OF RADIONuClIDES IN THE BIOSPHERE: A study conducted in Chernobyl in collaboration with Andra

1.11

Fe SbCs Sr Mn Co Ru Ce

0

100

80

60

40

20

Number of reliable values

Pb Te Am PuNa BeBa Zn Hg Cr Cd

Cereals

Root vegetablesFruit

Figure 1 Distribution of reliable translocation factor values according to element.

(1) Foliar transfer of radionuclides in agricultural ecosystems.



(2) Ukrainian Institute of Agricultural Radiology.

(3) Migration and transfer of iodine and chlorine.

(4) Migration and transfer of actinides.

obtain a translocation factor value strictly

reflecting foliar contamination, the soil is

protected from all types of contamination

and the canopy is shielded against rain,

thereby preventing interference due to root

transfer and rain washout (Figure 2). In addi-

tion, interception factors and leaf surface

index values are determined as a function of

time, the latter values serving to assess the

normal development of crops and enrich

available data.

This study is co-funded by Andra and

scheduled to continue for 36 months. It is

being conducted in an open-field test site

operated by UIAR(2) in the Chernobyl exclu-

sion zone. Previous IRSN-UAIR collaborative

studies on soil-plant transfers were also

conducted at this site, i.e. MITRIC(3) (2000-

2004) and MITRA(4) (2004-2007). The

implementation of this type of experimen-

tal study is extremely complex due to its

innovative character (natural conditions,

radionuclides investigated) and the accu-

racy targeted (translation factors accurate

to within 10%). Beyond the scientific aspect,

the technical challenge lies in designing

and sizing the experimental setup to achieve

a minimal dispersion of measured values

and thereby ensure good reproducibility of

results. Due to restrictions in terms of crop

surface area and available resources (infra-

structure, personnel), the various technical

criteria to be considered in designing the

experimental setup have been studied using

a design optimization analysis tool.

The study determined that it was par-

ticularly important to achieve proper con-

trol of the contamination phase to achieve

reliable results. This was therefore the main

goal targeted during the first crop cycle

(2008).

This cycle was also devoted to implementing

the experimental setup and evaluating its

efficiency. Studies in controlled environments

(greenhouses) were conducted in parallel

for preliminary testing prior to open-field

application. The results of this first crop

cycle, expected in late 2008, should benefit

the next two cycles, which are to be

performed under controlled conditions.

Figure 2 Three main phases of foliar transfer experiments: protection of soil (a), foliar contamination/interception (b) and crop control with rain protection and precipitation redistribution system (c).

a b c



1.12

Dominique BOUSTRadioecology Laboratory of

Cherbourg-Octeville

The Seine estuary is the only outlet of a

catchment area of approximately 75,000 km2,

strongly marked by human activity. Every

year, the river carries a few million tons of

sediment particles containing a large num-

ber of contaminants resulting from human

activities. This sediment flow is partially

discharged in the eastern bay of Seine dur-

ing high river flow periods, causing silting of

halieutic areas (spawning areas) and tour-

istic areas (Calvados beaches), and the

development of subtidal mudflats. These

processes are accelerated by natural filling

of the estuary and changes in its geometry

due to harbour developments.

At the same time, sediment particles of marine

origin mix with the estuarine sediment pool

and contribute to filling the estuary. They may

even move upstream as far as the region of

Rouen, as demonstrated by the upstream

decrease of 60Co concentrations, a radionuclide

mostly released by the spent fuel processing

plant at La Hague.

The MEDIUM project (2004-2007) set out

to characterize these two sediment contri-

bution pathways (marine and riverine), using

mineralogical markers (e.g. clays) and geo-

chemical markers (stable elements, radio-

nuclides) to determine the respective

contributions over a geographical area

spreading from the Poses dam (40 km

upstream of Rouen) to the eastern coast of

the Cotentin peninsula.

For this purpose, IRSN’s Radioecology

Laboratory measured the activity of natural

and artificial radionuclides in the fine sedi-

ment fraction (< 50 µm). Results of 238Pu

and 239, 240Pu activity measurements are

presented below.

Figure 1 shows the variations of 239, 240Pu

activity concentrations and 238Pu/239, 240Pu

activity ratio in fine sediment fractions

between the Poses dam (upstream limit of

the dynamic tide) and Cherbourg.

As expected, in stations located upstream

of the Seine and Orne dams, the 239, 240Pu

concentrations were low and the 238Pu/239,

240Pu activity ratios were charac ter istic of

fallout from atmospheric tests (i.e. free from

any industrial influence). In other stations, 239, 240Pu concen trations clearly indicated two

sets of values: on the one hand, values of less

than 0.4 Bq.kg-1 dry weight (in certain stations

on the banks of the Seine) and, on the other

hand, values ranging from 0.8 to 1.2 Bq.kg-1

dry weight, showing an increase in contami-

nation in the estuary and western bay of

Seine (including the Orne river). The 238Pu/239,

240Pu activity ratios justify this distinction.

The lowest 239, 240Pu concentrations cor-

respond to low isotopic ratios, ranging from

0.07 to 0.15. In the Seine estuary and bay

(including the Orne river), the highest con-

centrations correspond to isotopic ratios

ranging from 0.34 to 0.39.

These results show that the entire river-bay

continuum, including the Orne river up to

the dam located 16 km upstream of the

estuary, is filled with a relatively homoge-

neous sediment pool containing marine

particles marked by releases from the spent

MEDIuM PROjECT: Study of sediment mixing and dispersion using particulate markers in the Seine estuary



fuel processing plant in La Hague (isotopic

ratio of 0.4).

The low isotopic ratios measured in a few

stations along the Seine can be explained

by the mixture in varied proportions of two

sediment pools: a very old pool exclu-

sively marked by atmospheric fallout (iso-

topic ratio = 0.04), and a second stock

clearly marked by the discharge from the

spent fuel processing plant in La Hague

(isotopic ratio = 0.4).

A comparison with the measurements

obtained in 1995 shows that marine particles

have taken approximately ten years to reach

the Poses dam and remain present through-

out the river.

The MEDIUM project was funded by the

Seine Aval Public Interest Group and con-

ducted in collaboration with the Continental

and Coastal Morphodynamics Laboratory

(UMR-CNRS 6143 M2C) and Caen and

Rouen Universities.

Figure 1 238Pu and 239, 240Pu activity concentrations and 238Pu/239, 240Pu activity ratios in fine sediment fractions between Poses (201 km point) and Cherbourg (distances calculated from the 0 km point located at the Pont Marie bridge in Paris).

500 450 400 350 300 250 200

239, 240 Pu (Bq/kg dry weight)

4

3

2

1

0

Kilometric point (km)500 450 400 350 300 250 200

238 Pu/ 239, 240 Pu

0.5

0.4

0.3

0.2

0.1

0

Kilometric point (km)

Seine 2004 A River mouth Orne Cotentin

Che

rbo

urg

Che

rbo

urg

Le H

avre

Le H

avre

Roue

n

Roue

n



Sabine CHARMASSON, Antoine LE FAOUDERContinental and Marine

Radioecological Studies Laboratory

Hydrothermal sources located along oce-

anic ridges were identified in the late 1970’s

and certainly represent one of the major

oceanographic discoveries of the past 30

years, particularly with regard to the func-

tioning of ecosystems.

Hydrothermal circulation originates in the

network of fissures and crevices that devel-

op during the cooling of magma. Dense and

cold ocean water penetrates the earth’s crust

through these crevices and circulates when

it comes into contact with volcanic rock.

When it approaches magmatic chambers, its

temperature increases through conduction,

and its density decreases. As the ocean water

washes against basaltic rock, its physical and

chemical composition begins to change: its

temperature increases further, its acidity

increases, and it becomes loaded with min-

eral salts, metallic elements (Zn, Mn, Fe, Si),

radionuclides (U-Th families) and dissolved

gases. Under the effect of pressure, the fluid

thus formed flows back out onto the ocean

floor at focalized points. When the fluid

reaches the ocean floor, its sudden cooling

(due to the high thermal gradient) causes

massive precipitation of the elements trans-

ported (Figure 1). The precipitated particles

accumulate to form "smoker" chimneys

up to 2 m in diameter and 15 m in height,

out of which the hot fluid continues to flow.

The composition, flow rate and temperature

of the hydrothermal fluid vary from one site

to another, and even from one emission point

to another, depending on the degree of mix-

ture of the fluid and ocean water.

RADIOACTIVITY IN ORgANISMS at deep-sea hydrothermal sites1.13

Seawater

Mixture zone

Biological communities

Hydrothermal plume

Chemical and biological processes

Resuspension

Particles formed at low temperature

Erosion

Accumulation

Particles formed at high temperaturePlume contribution

Emission of hydrothermal

fluid

350 °C

2 °C

a b

c d

Figure 1 a) Black smoker chimney. b) Schematic diagram of a hydrothermal source. c) Shrimp swarm. d) Mussel colony.

a b

c d



Despite the extreme conditions in these

environments, several species (mostly endem-

ic) are present in the mixture zone between

the ocean water and hydrothermal fluid, where

conditions fluctuate dramatically. The biomass

may attain 50 kg of organic matter per square

meter, but the specific diversity is relatively

low. This "explosion" of life in an environment

without light, where the quantity of organic

matter originating from the surface is unlike

any other biomasses observed elsewhere, has

surprised the entire scientific community.

Discoveries reveal that the tissues of many of

these organisms contain bacteria capable of

using the energy released through the chem-

ical transformation of certain compounds in

the hydrothermal fluid (sulfurated hydrogen

in particular). This raises new questions regard-

ing the formation of life on Earth.

The main objective of the study conduct-

ed by IRSN is to validate the hypothesis of

the presence of high natural radioactivity

within the hydrothermal ecosystem, particu-

larly in the chemosynthetic fauna composing

it. In order to achieve this, the levels of impreg-

nation with radionuclides in certain organisms

colonizing these ecosystems (mussels, shrimp)

have been determined. The measured radio-

activity values (U and Th concentrations

measured by ICP-MS, Po and Pb concentra-

tions measured by alpha spectrometry) are

one to two orders of magnitude higher than

in coastal organisms (Figure 2). Such values

indicate chronic exposure to radiological and

chemical toxicity.

The study of the levels of impregnation with

contaminants is of considerable interest for

understanding ecotoxicological phenomena,

particularly bioaccumulation and transfers

by trophic chains. The objective here would

be to establish a relationship between the

determined levels of impregnation and the

development of a resistance to high ambient

toxicity in the organisms studied, essential

to their survival.

Figure 2 Activity concentrations of 234U (Bq.kg-1 dry weight) in the soft tissues of hydrothermal organisms (Bathymodiolus azoricus mussels and Microcaris fortunata shrimp), and in those of a coastal mussel (Mytilus galloprovincialis).

1 10 100 1,000

234U

Activity concentration (Bq.kg -1 dry weight)

M. fortunata

M. fortunata

B. azoricus

B. azoricus

B. azoricus

B. azoricus

M. galloprovincialis


RESEARCH SuPERVISOR HABIlITATION

January 25, 2008 laurent POuRCElOT submitted his paper

to obtain the Research Supervisor Habilitation

on the subject "Variability of atmospheric depo-

sition and transfer of artificial radionuclides in

soils" at the CNRS Surface Geochemistry

Re search Institute in Strasbourg.

DISSERTATIONS DEFENDED

April 25, 2008 Bénédicte BRIAND submitted a thesis

entitled "Use of discrimination trees to explain

radioactive contamination levels in plants" at

Cadarache in southern France.

June 13, 2008 Sandra lAgAuzERE submitted a thesis on

the subject "Influence of bioturbation of ben-

thic macro-invertebrates on the biogeo chemical

behavior of uranium in freshwater sedi ments"

at Cadarache.

September 9, 2008 Olivia DARCHEVIllE submitted a thesis

entitled "Influence of geochemical and micro-

biological soil components on the behavior of

selenium under oxic and anoxic conditions" in

Avignon.

October 27, 2008 Pierre MAzET submitted a thesis entitled

"Influence of transient flow on strontium mobil-

ity in soils partially saturated with water" at

Fontenay-aux-Roses in the Paris region.

October 30, 2008 Florence zEMAN submitted a thesis on the

subject "Binary-mixture toxicity experiment

on Daphnia magna: study of biological effects

of uranium and selenium, separately and in

mixture" at Cadarache.

December 5, 2008 François DuFOIS submitted a thesis entitled

"Modeling of particle transport in the Gulf of

Lions with a view to determining the fate of

radioactive tracers originating from the Rhone"

in Toulon.

OTHER kEY EVENTS

April 2008 Nomination of Denis Boulaud as Vice-

President of the Scientific Commission of the

National Research and Safety Institute

(INRS).

May 2008 Nomination of Frédérique Eyrolle as one of

the five members of the Scientific Committee

of the International Association for Sediment

Water Science (IASWS).

July 2008 The Heavy-Metal Induced DNA strand

Breaks project (HEMI-Breaks), conducted in

partnership with CEA and coordinated by

INSERM, was awarded ANR funding within the

framework of the "Contaminants, Ecosystems

and Human Health" research program. The

purpose is to perform a systematic study, at

the cellular level, of DNA two-strand breaks

produced by trace metals. An IRSN team will

study the effects of uranium to establish rela-

tions between these breaks and the impact on

individual fecundity, egg viability, embryonal

development in animal models.

July 2008 IRSN designated as national benchmark

laboratory for research on radionuclides (July 1,

2008).

The Directorate General for Food Safety (DGAL)

designated IRSN as the national benchmark

laboratory for research on radionuclides, in

replacement of the French agency for food

safety (Afssa). As such, IRSN will be respon-

sible for coordinating the network of DGAL-

a p p r ov e d l a b o ra t o r i e s , o r ga n i z i n g

interlaboratory aptitude tests, conducting offi-

cial analyses (when applicable), and confirming

laboratory results. This new mission confirms

IRSN’s expertise in radioactivity metrology

and also satisfies the objective to rationalise

the expertise of all organizations involved.

October 2008 Seminar for laboratories participating in ASN-

approved interlaboratory test programs.

In addition to performing environmental radio-

activity monitoring tasks, IRSN manages the

national environmental radioactivity monitoring

network as per Article R. 1333-11 of the French

public health code. In order to contribute data

to this network, laboratories must be certified

by the French nuclear safety authority (ASN).

For this purpose, in addition to submitting an

application for certification to the ASN, labora-

tories must periodically participate in inter la-

boratory test programs organized by IRSN. In

October 2008, IRSN organized the first seminar

on interlaboratory tests for environmental radio-

activity measurement laboratories. During this

seminar, the various aspects of the tests were

presented to 60 participating labora to ries.

kEY EVENTS and dates

1. 14



1. 14

October 2008 PROTECT (Protection of the environment from

ionizing radiation in a regulatory context), a

EURATOM coordination action implemented by

a consortium composed of the British Centre for

Ecology and Hydrology (CEH), the Swedish

radiation safety authority (SSM), the Norwegian

radiation protection agency (NRPA) and IRSN,

was finalized in October 2008. The consortium

issued several international recommendations

consistent with UNSCEAR and ICRP recommen-

dations on environmental radiation protec tion.

1environment radioactivity and the - irsn · 1 radioactivity and the environment ... the biological...

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