Évolution spatio-temporelle des concentrations, des rapports isotopiques et des facteurs de concentration du plutonium dans une espèce d'algue et deux espèces de mollusques en Manche

Abstract

(Manuscrit reçu le 6 février 1999, rPvisP le 30 m û t 1999, uccepté le 7 novembre 1999) F&SUMI?L'étude de la distribution spatiale et de l'évolution temporelle des isotopes du plutonium (238Pu, 239-24@Pu) chez des espèces indicatrices (Fucus serrutus, Putella sp., Mytilus edulis) a été réalisée le long des côtes de la Manche. Plusieurs époques ont été considérées, 1982-1983,1990-1993 et 19%. Les concentrations des différents i w topes sont inférieures à 1 Bq kg-lsec pour les années les plus récentes. Une diminution de ces concentrations depuis plusieurs années est observée et elle est associée à la diminution des quantités de plutonium rejetées par l'usine de la Hague. Des gradients de distribution dei isotopes le long des côtes apparaissent pour les fucus. La différence entre les rapports isotopiques des es@ces et des rejets conduit à discuter des diverses sources de radioactivité inîluençant les niveaux de plutonium. Enfin, les facteurs de concentration sont définis.ABSTRACT Variation of activity levels, isotope ratios, concentration factors in space and t h e of plutonium in seaweed and mollusc species along the coast of the English Channel.A study was carried out on the spatial and temporal variation of plutonium isotopes (2wrh~39~2%) in hioindicator species (Fucus serraîus, Patella sp., Mytilus edulis) sampled along the coast of the English Channel. Several penods of t h e were considered, covering 1982-1983, 1990-1993 and the year 1996. The activity levels of the radionuclides in question were l e s than 1 Bq kg-'dry basis. A decrease in these activities has been ohserved over a number of years in relation to a reduction in the amounts of plutonium released from the establishment of La Hague. 1,ongshore gradients are apparent in the radionuclide distribution for Fucus. The discrepancy between the isotope ratios measured in the bioindicator species and the releases from industrial sources leads to a discussion of the vanous source-terms affecting plutonium activities. Then concentration factors are defined.

Metals in marine environment (mollusc Patella sp., fish Labrus bergylta, crustacean Cancer pagurus, beach sand) in a nuclear area, the North Cotentin (France)

“…This chemical measurement campaign was intended to acquire reliable data for validating the models used by the NCRG to estimate concentrations of chemical substances in the environment from discharges data provided by nuclear facilities (AREVA NC, ANDRA, French Navy) and also aims to answer the societal questions about occurrence and concentrations. Although the impact of radioactive effluents released by the nuclear industry on radioactivity levels in seawater and marine species has been studied (Masson et al 1983;Germain and Miramand 1984;Bailly du Bois and Guéguéniat 1999;Germain et al 2000;Fievet et al 2006), there have been few studies of the impact of the released chemicals (Miramand and Bentley 1992). However, the quantities of chemicals that can be released by nuclear plants within regulation limits remain high.…”

Variations of 210Po and 210Pb in various marine organisms from Western English Channel: contribution of 210Po to the radiation dose

“…The data were acquired principally along the French Channel coast. Many studies are carried out in this region for artificial radionuclides ; Bailly du Bois and Guegueniat, 1999;Germain et al, 2000), because of the presence of a spent fuel reprocessing plant and several nuclear power stations, but there have been fewer studies on alpha-emitting natural radionuclides. Although many recent studies of 210 Po in the marine environment exist in the literature, few measurements have been published for different marine species on the French coast (Germain et al, 1995a,b;Bustamante et al, 2002;Masqué et al, 2002).…”

129I determination by direct gamma-X spectrometry and its application to concentration variations in two seaweed species

“…Temporal variations in the self-attenuation coefficient are related to variations in the elementary composition of the matrix, including variations in iodine in the case of seaweed. Our study focused on brown seaweed, more specifically Fucus serratus and Laminaria digitata, which are used as bio-indicators in environmental studies to monitor various pollutants [3][4][5][6][7][8][9]. The specificity of such seaweed resides in their sedentary nature on the one hand and the fact that they concentrate elements that are only soluble in their surrounding environment on the other hand.…”