Iodine-131 and various other radionuclides were released into the atmosphere from the damaged Japanese reactors of Fukushima Dai-ichi from 12 to 22 March 2011. The contaminated air mass was detected in France after 24 March; samples of grass, vegetables, and milk have been analyzed for (131)I by the IRSN, considering the fact that few values of iodine-131 transfer parameters have been directly measured in situ, due to the radioactive decay of this isotope. Data are compared with calculated values according to the air iodine concentration. The apparent dry deposition velocity of iodine on grass is therefore estimated to range between 1 × 10(-3) and 5 × 10(-3) m s(-1) from site to site. In addition, the grass to milk transfer factors are 2.8 × 10(-2) and 3.6 × 10(-3) d L(-1) for goat's and cow's milk respectively. These parameters fit well with the current values usually considered for radioecological assessment.

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Cette synthèse bibliographique décrit le com ortement du polonium-210 dans l'environnement terrestre. Les sources du "' Po dans l'atmosphère varient notamment avec la localisation géographique et la présence ou l'absence d'activités minières. Dans les sols, le polonium, du fait de son origine aîmosphérique, est concentré dans les premiers centimètres. C'est un élément peu mobile qui s'adsorbe sur les surfaces minérales et peut (co)précipiter avec les (oxy)h droxydes métalliques ou sous forme de sulfure. La voie d'entrée majoritaire du ''$0 dans la végétation est le dépôt foliaire qui n'est pas, ou peu, suivi d'incorporation ou de translocation. Le transfert du ""Po aux animaux s'effectue principalement par ingestion, avec des facteurs de transfert relativement élevés. Dans les hydrosystèmes dulçaquicoles, le ''%O est généralement immobilisé sous forme de Po(IV) insoluble eüou associé à la phase particulaire ou colloïdale. Le plancton, les invertébrés et les poissons concentrent le *'"Po, surtout dans les tissus mous. Le polonium, radioélément naturel omniprésent dans l'environnement, est susceptible d'induire pour l'homme une exposition significative par rapport à d'autres radionucléides naturels ou artificiels. Les études -essentiellement des mesures in situqui lui sont consacrées restent très descriptives, aussi, des travaux expérimentaux permettant de mieux comprendre et de modéliser son comportement dans le milieu terrestre seraient utiles. &SuMÉABSTRACT "@Po hehaviour in terrestrial environment: a review.This hibliographical review illustrates the behaviour of 210 polonium in the terrestrial environment. Sources of "%o in the atmosphere vary especiallg with the geographical localization and the occurrence or the absence of mining activities. In soils, polonium hecause of its atmospheric origin, is concentrated in the first upper centinieters. 'lbPo is rather immobile and adsorbed on mineral surfaces; it can (co)precipitate with metallic (0xi)hydroxides or in the form of sulphide. The main transfer pathway of 2i0Po to vegetation is foliar deposit, which is not, or only slightly, followed by incorporation or translocation. 2i0Po is transferred to animals mainlg by ingestion, with relatively high transfer factors. In freshwaters, ""Po is generally immobile in the form of insoluble Po(IV) a n a o r associated with the particulate or colloidal phase. Plankton. invertebrates and f ï h concentrate the 2"k'o, especially in soft tissues. Polonium, which is an omnipresent natural radionuclide, is likely to occasion a significant exposure ta man, compared with other natural or artificial radioisotopes. Nearly al1 studies derive from in situ measurements and are very descriptive, therefore experimental work aiming at a hetter knowledge and modeling of its hehaviour in the terrestrial environment would he useful.' IRSN. Service d'érudes et de recherche' radioSc«logiqiic\ en Iahoratnire. Lahnratoire de iadinécologie expérinientale, C.E. Cadarache. B.P. 13, 131 15 S3iiit~Paul-L27~Uuinnce Cedex. Fraiicc

From 1988 to 1993, the Nuclear Safety and Protection Institute (Institut de Protection et de Sûreté Nucléaire--IPSN) conducted experimental programs focused on transfers to vegetation following accidental localized deposits of radioactive aerosols. In relation to vegetable crops (fruit, leaves, and root vegetables) and meadow grass these experiments have enabled a determination of the factors involved in the transfer of cesium, strontium, and ruthenium at successive harvests, or cuttings, in respect of various time lags after contamination. The dynamic modeling given by these results allows an evaluation of changes in the mass activity of vegetables and grass during the months following deposit. It constitutes part of the ASTRAL post-accident radioecology model.