NATURAL RADIOACTIVITY IN THE AQUATIC COMPONENTS OF THE MAIN FRENCH RIVERS

Radioactivity measurements were taken in the main French rivers. Six natural radionuclides were measured in the aquatic compartments: K-40, U-238, Ra-226, Th-232, Pb-210 and Be-7. Global natural radioactivity in the different components of the aquatic ecosystem was about 1 Bq.l-1 in filtered water, 110 Bq.kg-1 wet weight in fish, and between 1300 and 1800 Bq.kg-1 dry weight in sediment and in aquatic vegetation. No real variation between rivers could be shown in relation to the granulometry of sediment, species differences of fish or vegetation. The only source of variation in natural radioactivity seemed to be linked with the geological nature of the river basins.