The environmental abundances of 129I and 127I in Lower Saxony, Germany, and their pathways to animals and man were investigated. The iodine isotopes are in severe disequilibrium in the different environmental compartments. Today, the environmental isotope ratios range from 10-6 to 10-10. The highest ratios were found in North Sea water, the lowest in deep soil samples and ground water. A differentiation by about a factor of ten between the iodine isotopes was observed for different air-borne iodine species. Time series for iodine in precipitation show a decade-long increase of 129I fallout until the 1990ties and an ongoing constant input of 129I with deposition densities of ~ 15 mBq m-2 per year. In surface waters, a dilution of the fall-out iodine takes place by stable iodine which is just weakly adsorbed in the soils. The isotope ratios in soils and ground waters demonstrate a high mobility and an accumulation of 129I in the water unsaturated soil zones and an efficient migration into water saturated soil layers and ground water. The transfer into the food chain is ruled by the complex situation in the water-soil system. Given the environmental 129I abundances, the relatively low 129I/127I ratios in human thyroid glands (2 × 10-9 - 3 × 10-8) can only be explained by additional iodine sources with low ratios in the diet.

In uranium mill tailings, oxides and oxi-hydroxides are responsible of about 70% of the radium immobilization, half being associated to amorphous forms (mainly iron and manganese oxides/oxi-hydroxides). With time, crystallization of these amorphous forms can occur, inducing a redistribution of radium between solids and solution. If the amount of mobile radium increases, the impact of these tailings on the environment may become significant. The aim of this study is to determine the amount of 226Ra released in solution during the crystallization process of hydrous ferric oxi-hydroxide (HFO) containing 226Ra. A reproducible co-precipitation procedure is developed. The transformation of Ra-HFO co-precipitate in crystallized forms (goethite, hematite, ...) is studied by ageing amorphous solids at 40$^{\circ}$C in different solutions.After co-precipitation, about 20% of the initial 226Ra present in solution is associated to amorphous HFO. At 40$^{\circ}$C, whatever the solution composition (MES or NaClO4), the solid evolution is very slow and, after 3-5 months, no significant amount of crystalline form is noticeable. Simultaneously, the amount of 226Ra present in solution is constant in MES and NaClO4 medium. In comparison, 226Ra sorption shows off inclusion of 226Ra in Ra-HFO precipitate.

We review collated data and available models for estimating the transfer of radionuclides to terrestrial biota within the European Arctic. The most abundant data are for radiocaesium and radiostrontium although many data for natural radionuclides are available. For some radionuclides no data are available for describing transfer to Arctic biota. Allometric-kinetic models have been used to estimate transfer for radionuclide-biota combinations. Predicted values were in good agreement with observed data for some radionuclides although less so for others. There are no bespoke models to enable the dynamic prediction of radionuclide transfer to Arctic biota. A human Arctic foodchain model has been adapted to estimate 137Cs and 90Sr transfer to some Arctic biota. There are many factors of Arctic ecosystems which may influence radionuclide behaviour including short growing seasons, prolonged soil freezing, and effects of low temperatures on biological rates. If exposure to ionising radiation in Arctic ecosystems is to be robustly predicted such factors must be fully understood and incorporated into models.

A number of frameworks have been proposed to assess the protection of wildlife from ionising radiations. In this paper we compare the predictions of transfer parameters recommended by one of these frameworks (FASSET) with observed whole-body 90Sr and 137Cs activity concentrations in a range of mammal and invertebrate species sampled within the Chernobyl exclusion zone. Predicted activity concentrations are generally within the observed ranges and mean predictions for reference organisms are similar to, or circa one order of magnitude higher than, the observed means. However, some predictions are more than one order of magnitude lower than observed values. No data were available for animals to test predictions for the other radionuclides released by the Chernobyl accident. In a separate paper the outputs of this assessment will be used to estimate doses to reference organisms and compare these to observed radiation induced effects reported within the Chernobyl zone.

In this paper we use the FASSET framework to estimate absorbed dose rates for biota within the Chernobyl exclusion zone. The estimated doses are compared to observed biological effects within the Chernobyl exclusion zone and effects expected from summaries of existing knowledge and the extent of contamination. Although paucity of observations under conditions of chronic irradiation makes direct comparison difficult, the biological effects observed in the Chernobyl exclusion zone over the period considered here (1988-2003) are broadly in agreement with those which may have been expected.

This paper presents a dynamic box model for the radionuclide behaviour in rivers on medium- and long-term periods (several days to several years). The river is described as a succession of boxes representative of its different reaches. In each reach, the compartments are the water column and three bottom sediment layers. Called interface, the first layer plays a fundamental role for the vertical exchanges of solid radionuclide phases between the water column and the sediment. The second layer results from the consolidation of the previous one. Its interstitial water is mobile and the dissolved radionuclide phases can be exchanged with the water column. It is called active. The last layer results from the consolidation of the active layer. Its interstitial water is slightly mobile and it is assumed that its dissolved radionuclide phases cannot be exchanged. It is called passive. In each compartment, the model computes the temporal evolution of the radionuclide activities in the main abiotic and biotic components. The abiotic components are the water and different matter classes classified according to their deposit kinetics. The biotic components are phytoplankton, zooplankton, and fish distributed in planktonivorous and omnivorous species, in water column and macrobenthos in bottom sediment.

In freshwater, radionuclide transfers depend both on exchanges between liquid and solid phases and on mass transfers between suspended and bottom sediment. Whereas the former ones depend on chemical processes (sorption/desorption, complexation ...), the latter ones are regulated by hydrological and sedimentary considerations (dispersion, erosion, deposit ...) closely related to the interactions between flow, suspended matter and bed sediment. Previous studies highlight the need to consider the matter heterogeneity and its specific sediment dynamics to correctly report the in homogeneity of fluxes in time and in space. These considerations lead us to develop an experimental method to distinguish the different particle groups present in natural water, mainly according to their settling kinetics. In this context, this paper presents the experimental protocol TALISMEN to characterize a natural bulk suspension according to its main settling kinetics groups. In a first step, this identification is achieved by the use of a settling tank that allows the monitoring of the suspended solid concentrations at various depths, combined to a settling model applying a multi-class approach. In a second step, the particle groups are isolated and characterized. The sorption property of each group toward 137Cs is determined by estimation of its distribution coefficients (kd) and sorption kinetics.

The objectives of this work are to study the behaviour of 238U and its daughters in the continental environment and to determine the radiological impact of U mining past activities in the Haute-Vienne French administrative division. The distribution of radionuclides among different size fractions was investigated upstream and downstream mines. Particulate (>0.45μm) and dissolved (<0.45μm) fractions were separated by filtration and analysed by gamma spectrometry. A preconcentration step by evaporation was elaborated and validated for liquid samples. Results indicate that radiological impacts of U mines are the enhancement of radionuclides activities and a change of their distribution between particulate and dissolved fractions at 0.45μm. While activity levels depend on the input intensity, the distribution is controlled by the mine water treatment witch reduces drastically the contribution of mine radionuclides in streams. Analysis of particles from traps and sediments confirms that the distribution of mine radionuclides promote their accumulation in lacustrian sediments. Nevertheless, the impact of the past activities is very limited in space. Indeed, it becomes weak at 10 km downstream the inputs and is no more detectable at 30 km downstream.

Field experiments in the Chernobyl exclusion zone have been carried out to determine the behaviour of the radioactive halogens 36Cl and 125I (as a surrogate for 129I) in the soil-plant system and along human food chains. The investigations on the migration in four types of soil of the two radionuclides showed that the vertical transport of chlorine was the most rapid: 9 months after the contamination the residual fractions of 36Cl in the 20 cm arable layer varied from 1% to 3% according to soil type. For iodine this percentage was less than 3% in any case. The soil to plant transfers were quantified for various agricultural crops (cereals, grass, root vegetables, leaves vegetables and fruit vegetables) and for several kinds of soils. The root uptake of 36Cl by plants was particularly important. As a result of this very high biological assimilation about 60% of the contamination was extracted from the soils by the plants after one vegetation period. For iodine the concentration ratios values are 2 or 3 order of magnitude lower than for chlorine.

Some 3×109 kg of phosphogypsum (PG) wastes are annually generated by two fertiliser-production factories in Huelva (south-western Spain). PG has relatively high concentrations of 226Ra and other radionuclides, with an special concern due to the 222Rn emissions. These wastes could be used to improve the fertility of agriculture soils in a large former marsh area of the Guadalquivir river. Thus, it is interesting to study the levels and behaviour of natural radionuclides within this system to evaluate the radioactive impact of this amendment. An agronomical test is being conducted by one of the authors in an experimental farm in Lebrija (Seville). The soils are treated with 13 and 26 t ha-1 of PG, 30 t ha-1 of manure. Each treatment was repeated twice and continued for two years with beetroot and cotton plant production. We are measuring 226Ra (by alpha counting and gamma spectrometry) and U isotopes (by alpha spectrometry and ICP-MS analysis) in drainage waters, soils and vegetal-tissues samples. The PG used in the treatment has 620 ± 70 Bq kg-1 of 226Ra. The drainage waters have 226Ra contents similar to those from non-contaminated natural waters, but the uranium concentrations are one order of magnitude higher. Our results are suggesting that the major uranium input comes from the application of phosphate-fertiliser. No significant levels of radionuclides were found in the vegetal tissues.

Kinetic transfer coefficients are important parameters to understand and reliably model the behaviour of non-conservative radionuclides in aquatic environments. This report pertains to a series of radiotracer experiments on 239Pu uptake in natural unfiltered waters from the Hueznar reservoir (southern Spain). The experimental procedure ensures the preservation of environmental conditions and the dissolved Pu activity was measured by liquid scintillation technique. The data suggest that the main pathways for Pu uptake consist of two parallel and reversible reactions. We studied the effects of suspended matter concentrations and the specific surface area on the kinetic transfer coefficients.

The protection of biota from ionising radiations needs reliable predictions of radionuclide dynamics in wild animals. Data specific for many wild animal - radionuclide combinations is lacking and a number of approaches including allometry have been proposed to address this. However, for 14C and 3H, which are integral components of animal tissues and their diets, a different approach is needed. Here we propose a metabolically based model which can be parameterised predominantly on the basis of published metabolic data. We begin with a metabolic definition of the 14C and OBT loss rate (assumed to be the same) from the whole body and specific organs. The mammalian body is conceptually partitioned into compartments (body water, viscera, adipose, muscle, blood and remainder) and a simple model defined using net maintenance and growth needs of mammals. The model is tested with data from studies using rats and sheep. It provides a reliable prediction for whole body and muscle activity concentrations without the requirement for any calibration specific to 3H and 14C. Predictions from the model for representative wild mammals) are presented. Potential developments of a metabolic model for birds and the application of our work to human foodchain modelling are also discussed.

In order to perform radiological impact assessments of radioactive waste disposals, a compartmental model taking into account generic data for biosphere transfer parameters values is usually used. To improve its performance assessments calculations, Andra (French national radioactive waste management agency) decided to adapt this type of biosphere model to its sites conditions. On one hand, specific models have been developed such as model for 36Cl based on isotopic dilution and on local stable chlorine contents. On the other hand, biosphere transfer factors values are issued from experimental studies adapted to Andra context: soil characteristics, climate, agricultural habits and species. These specific data are useful only if main factors controlling mobility have been determined previously for each radionuclide, which implicates good knowledge of environmental radionuclides behaviour. This site-specific approach allows to reduce uncertainty and range of variation of impact calculations and ensure a consistent model. It helps also to achieve scientific community approval by showing mastery of radionuclides environmental processes and public understanding by focusing demonstration on real local conditions. The methodology is fully presented. Two examples for uranium and chlorine and the limits of this approach are given.

In a period between 1943 and 1974 radioactive wastes were temporary buried on a special site on the territory of RRC “Kurchatov Institute". The site monitoring held since the end of the 80s showed that contaminants are located not only on the surface and in the ground but they have also spread in groundwater. The paper presents preliminary results of the work on development of numerical models of radioactive contamination migration the waste disposal site. The objectives of the work were to evaluate the existing contamination plume, to determine mechanisms of contaminant migration on the site and to develop a numerical model of radioactive contamination transport that would allow correctly predicting further plume spreading for making necessary engineering decisions. Based on laboratory findings and radiation monitoring data obtained at the waste disposal site and its adjacent areas, there were determined the site hydrogeological structure and parameters, and a geoinformation database was developed. Three-dimensional numerical models of groundwater flow (using the MODFLOW code) and mass transport (using the MT3DMS code) were built and verified against field measurements. Using these models, preliminary predictions of radionuclide migration from the waste disposal site were made.

An accurate model of atmospheric dispersion of radionuclides over the complex terrain of La Hague reprocessing plant (North Cotentin, France) has been developed by COGEMA, in partnership with Paris VI University, and has been yet adapted for an other industrial site (Marcoule). This model, called CEDRAT, takes into account areas typically outside the validity range of Gaussian models: topography and building influence, short-distance (beyond 500 m from the release point) and various atmospheric stability conditions. CEDRAT allows to reach an effective compromise between rapidity (30 min on a 6000 nodes grid, on a standard PC), robustness and accuracy, coupled with a user-friendly interface. The validation process consisted first of a comparison with the 3D reference model MERCURE, developed by EDF, and then, results of both models were compared on release scenarios thanks to tracer data (Krypton-85, an inert gas released from a height of 100 m) collected at five monitoring stations around the site. Then a second level of comparison, presented here, was made in collaboration with the IRSN Cherbourg Radioecological Laboratory, on ground and altitude (collected with a tethered balloon) field data.

Foliar transfer of transuranium elements had not received the same attention as other long-lived radionuclides, such as the well-known classical fission products Cs and Sr. Thus, the aim of this study was to compare the foliar transfer parameters of 241Am and $^{239,240}$Pu with those of 137Cs and 85Sr. Bean plants (Phaseolus vulgaris) at flowering development stage were contaminated by soaking their first two trifoliate leaves for 3 hours in a solution containing 241Am, $^{239,240}$Pu, or 137Cs and 85Sr. Results showed that transuranium elements were more retained by leaves than Cs or Sr. The mean leave-to-pod translocation factor of Am was of the same order as that of Sr, showing that the behaviour of Am was close to the behaviour of Sr. Translocation of Pu was significantly lower than for Cs, Sr or Am and occurred preferentially in leaves. Differential mobility of Am, Pu, Cs and Sr were compared to those used in related studies. Comparison showed that, when specific values of representative radioecological parameters are lacking, the behaviour of Am and Pu towards foliar transfer may be conservatively described as “Sr-like".

A dynamic compartment model was developed to evaluate the transport of accidentally released radionuclides onto rice-fields. In the model, the surface water compartment and shoot-base absorption were introduced to account for the effect of an irrigation which is essential to rice cultivation. Allowance was made for the effect of a soil mixing by a plough and an irrigation before transplanting the rice. The rate of root-uptake and shoot-base absorption were modeled in terms of the function of the biomass. In order to test the validation of the model, some 137Cs deposition experiments were carried out for several years while cultivating rice in a greenhouse using soils sampled from rice-fields around Kori, Yonggwang and Ulchin nuclear power plants in Korea. The model prediction agreed well to the experimental results within one order of magnitude.

Long-lived radionuclides 137Cs and 90Sr have been regularly monitored since the 1960's in dairy milk in Finland. The aim of this work was to study regional differences in long-term behaviour of 137Cs and 90Sr in dairy milk including the nuclear weapons tests period and the period after the Chernobyl fallout. In the milk production areas in Finland soil types vary from clayish to humus and peat soils. Although total 137Cs deposition from nuclear weapon testings was approximately the same in all regions, 137Cs concentrations in dairy milk during the 1960s ranged between 5 and 35 Bq/l being highest in regions with high proportion of peat soils. The uneven deposition after the Chernobyl accident before the start of the growing season gave rise to 137Cs concentrations in dairy milk ranging from 3 Bq/l to 60 Bq/l. In the milk production areas dominated by organic soils the ecological half-lives for decrease of 137Cs were higher in the regions with clayish soils. Half-lives of 90Sr for longer time intervals were considerably longer than those for 137Cs. The long-term data on behaviour of 137Cs and 90Sr in dairy milk can be utilized in testing food chain models.

The investigation wells for a control of the underground water contamination were bored after the cratering explosions at the Semipalatinsk Test Site, now they are restored partially. The analysis of the retrospective information of the Institute of Global Climate & Ecology (Moscow, Russia) give a possibility to choose wells and terrains for the successful study of radionuclide migration with the underground water. The epicentral zone, the crater and the territory with radius 1,5 km around the explosion “1003" were investigated under the ISTC project K-810. Underground water and soil samples were taken at the two expeditions of 2003. The chemical extraction methods taking into account the water mineral composition, gamma-spectrum methods, methods of liquid scintillation spectrometry and methods of alfa-spectrometry were used. The modern radionuclide content (3H, 90Sr, 137Cs, 239+240Pu, 241Am etc.) of the underground water is presented and compared with a radionuclide content of soils around crater. The retrospective information has been added by these modern data. The vertical radionuclide distrioin soils is presented.

During the Chernobyl accident, large areas in Europe, particularly forests, were contaminated by radiocaesium. Soil-plant transfer is often the first step by which 137Cs enters to food chains by incorporating the forest biogeochemical cycle. The present work is devoted to assess the soil-plant transfer of radiocaesium in weakly contaminated forest area, in the Franche-Comté region (16 202 km2) in North Eastern France. This region has been markely contaminated after the Chernobyl accident. Twelve sites, with various functional features and high diversity of ecological contexts were selected to sample forests trees. Two species (Picea abies and Fagus sylvatica) and two organs, (leaves or needles and young branches) were sampled for radioactivity measurements. Radiocaesium activities in soils varied between 61 to 280 Bq.kg-1DW at 0-5 cm depth and between 14 to 224 Bq.kg-1DW at 10-15 cm. Radiocaesium activities in leaves, needles and branches displayed high variability. We reported a large variability of Aggregated Transfer Factors (Tag) values with respect to vegetation type, organ type and soil features. The activity concentration in the leaves and needles were generally higher than those measured in the branches. The Tag values could be explained by the radiocaesium bioavailability variability in relation to soil type, soil features and environmental parameters.