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[en] This study is part of researches about nuclear accident prediction consequences on the environment. It concerns transfering of molecular gaseous iodine into liquids and especially precipitation scavenging below the cloud (washout). Bibliographic data directly concerned with this study (iodine's aqueous chemistry, aqueous to gaseous phases transfer) and also with its global frame-work (atmospheric release from a nuclear reactor in accidental situation and the behaviour of atmospheric iodine) are presented. Several experimental approaches have been performed in laboratory and on field. An aqueous to gaseous phase transfer simulator allowed us to isolate parameters involved in absorption and desorption of the halogen. Field experiments permit to quantify dry deposition on different solutions and to get a better insight of the phenomenon. Extrapolation of the whole results to precipitation scavenging of gaseous iodine I₂ by natural rains suggests that the process is an irreversible one. Washout rate values acquired during rainy experiments with molecular iodine emission or in a laboratory rainfall simulator agree with literatures data relative to irreversibility. However and even if reversibility was efficient it was not possible to clearly exhibit it according to experimental conditions. Moreover, the analytical iodine method which leads to a good experimental study has been presented

[en] In the field of freshwater environment, many studies have been carried out to characterize the interaction of radionuclides with the solid and liquid phases that constitute the physical components of natural ecosystems. These exchanges depend upon physical, chemical and biological conditions characterizing the system. To quantify the distribution of the radionuclide between dissolved and particulate forms, a radio expressed as Kd or distribution coefficient, is generally used. The major environmental parameters that influence the Kd values are: contact time and suspended matter concentrations, quality and granulometry of the solid phase (especially for cesium, cobalt, manganese, silver, iodine), stable isotope concentrations in the liquid and solid phases (cesium, cobalt, manganese, silver), redox conditions in the two phases (cesium, manganese), mineral composition of the liquid phase (cesium), pII of water (cobalt, manganese, silver), presence of dissolved organic ligands (cobalt, antimony, iodine). As a result, for each radionuclide, the range of the distribution coefficient is considerable. However, for a given ecosystem at a given period of its hydrological cycle, this range can be reduced if the values of the main environmental parameters that influence the kd values are known. The site-specific values of Kd can also be determined by experiments carried out under appropriate conditions in laboratory or in situ. (author)