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
newsflashnewsflashnewsflashnewsflashnewsflashnews
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
newsflashnewsflashnewsflashnewsflashnewsflashnews
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
16 2008 Scientific and Technical Report - IRSN
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
IRSN - 2008 Scientific and Technical Report 17
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-
18 2008 Scientific and Technical Report - IRSN
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
IRSN - 2008 Scientific and Technical Report 19
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
20 2008 Scientific and Technical Report - IRSN
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
IRSN - 2008 Scientific and Technical Report 21
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 • NiNi+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
22 2008 Scientific and Technical Report - IRSN
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].
Radioactivity in the environment 1. 1
IRSN - 2008 Scientific and Technical Report 23
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
24 2008 Scientific and Technical Report - IRSN
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 (%)
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
Radioactivity in the environment 1. 1
IRSN - 2008 Scientific and Technical Report 25
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
DNA in comet tail (%)
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
26 2008 Scientific and Technical Report - IRSN
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
IRSN - 2008 Scientific and Technical Report 27
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
newsflashnewsflashnewsflashnewsflashnewsflashnewsflash
28 2008 Scientific and Technical Report - IRSN
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).
IRSN - 2008 Scientific and Technical Report 29
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).
30 2008 Scientific and Technical Report - IRSN
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
IRSN - 2008 Scientific and Technical Report 31
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)
Coating (3 mm) Coating (5 mm)Non-treated
glass
Low-maintenance
glassCoating (2 mm)
Coating (3 mm) Coating (5 mm)Non-treated
glass
Low-maintenance
glassCoating (2 mm)
DIAPEG 1(air sampling)
DIAPEG 2(air sampling)
DIAPEG 3(air sampling)
DIAPEG 4(air sampling)
DIAPEG 5(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
32 2008 Scientific and Technical Report - IRSN
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.
Radioactivity in the environment
IRSN - 2008 Scientific and Technical Report 33
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
Low-maintenance glass
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 glassLow-maintenance
glass
Coating with roughness value of 2 mm
Coating with roughness value of 3 mm
Coating with roughness value of 5 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%).
34 2008 Scientific and Technical Report - IRSN
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
Coating with roughness value of 2 mm
Coating with roughness value of 3 mm
Coating with roughness value of 5 mm
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
Coating with roughness value of 2 mm
Coating with roughness value of 3 mm
Coating with roughness value of 5 mm
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.
Radioactivity in the environment
IRSN - 2008 Scientific and Technical Report 35
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.
36 2008 Scientific and Technical Report - IRSN
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.
IRSN - 2008 Scientific and Technical Report 37
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.
38 2008 Scientific and Technical Report - IRSN
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
1959
1961
1963
1965
1967
1969
1971
1973
1975
1977
1979
1981
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
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.
Radioactivity in the environment
IRSN - 2008 Scientific and Technical Report 39
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 surf