7. Strontium 90 in the French metropolitan environment

The strontium 90 present in the environment of mainland France comes almost exclusively from fallout from nuclear weapons testing. Measurements show a significant decrease over time in the mass and volume activities of this radionuclide in the environment.

As a result, strontium-90 mass activities in soils have decreased overall by more than an order of magnitude since 1963 (see figure 11 ). This decrease is largely due to strontium's solubility, which facilitates its migration to the depths of the soil and its drainage into watercourses. Strontium-90 mass activities measured from 1975 to 1990 in soil samples taken from different localities show a spatial variability linked to annual rainfall heights in these...