134Cs and 85Sr in fruit plants following wet aerial deposition

The knowledge of processes concerning the radiocontamination of fruit after a spike release can improve the understanding of exposure through ingestion of food and better assess the public dose. The fate of 134Cs and 85Sr in the above ground part of different species of fruit plants after wet deposition on leaves or on fruits was compared. Grapevines, apple trees, and pear trees grown under field conditions were contaminated with 134Cs and 85Sr either via leaves or via fruits before ripening. Spiked and non-spiked fruits and leaves were picked 50 d later, at harvest time, and their 134Cs and 85Sr contents were measured by gamma spectrometry. The residual fraction in leaves was on average 7% of the initially applied 134Cs and 8% of 85Sr, while that in fruits was 60% of 134Cs and 28% of 85Sr. Rinsing of fruits before consumption causes a loss of 24% for 134Cs and 36% for 85Sr present in fruit at harvest. Leaf-to-fruit transfer factors are considerably higher for 134Cs, 4% of the applied activity, than for 85Sr, 0.04%. Leaf-to-leaf are also higher on average for 134Cs than for 85Sr. Transfer also occurs from spiked fruits to leaves; its extent is affected more by the kind of plant than by the radionuclide. 134Cs and 85Sr are transferred to fruits and leaves of non-contaminated branches to a lesser extent than within the contaminated branches.