Cesium-134 and strontium-85 in strawberry plants following wet aerial deposition.

The understanding of the processes that control the behavior of radionuclides in crops can support policymakers to take actions to protect the environment and safeguard human health. Data concerning the behavior of radionuclides in fruits are limited. Strawberry (Fragaria x ananassa Duchesne) plants were contaminated on the aboveground part by sprinkling an aqueous solution of 134Cs and 85Sr at three growing stages: predormancy, anthesis, and beginning of ripening. Intercepted activity was more affected by the posture and physical orientation of leaves rather than by leaf area or biomass. Fruit interception ranges from 0.2 to 1.2% of the sprinkled activity. Translocation coefficients from leaf to fruit are on the order of 10(-4) for 134Cs and 10(-5) for 85Sr. Translocation reaches its highest intensity between anthesis and ripening. If deposition occurs when plants are bearing fruits, the fruit activity will be affected by the activity initially deposited on the fruit surfaces. This is important for 85Sr as it is not translocated in the phloem. The loss of the dead leaves at the resumption of growth causes high plant decontamination, but a fraction of both radionuclides remains in the storage organs, roots, and shoots, which is retranslocated to fruits in the following spring. The values of the environmental half-time, t(w), after deposition at predormancy are 114 d for 134Cs and 109 d for 85Sr. Cesium-134 tends to be allocated to fruits, while 85Sr remains in leaves and crowns. Translocation of radionuclides to roots results in soil contamination.