Mobility of superficially applied caesium-134 and strontium-85 in apple branches under precipitation-free conditions
Abstract
The recovery of superficially applied 134Cs+ and 85Sr2+ in apple branches protected from precipitation decreased with time. Translocation of 134Cs to uncontaminated branches declined rapidly with the distance from the contaminated branches. Extensive translocation of 134Cs from foliage to fruits occurred within the same branch: after 84 d, 50% of the recovered activity was found in fruits and most of it in the edible part (excluding peel). On the other hand, 85Sr was less mobile and in virtually all fruit 85Sr was in the peel. Rinsing leaves removed 30% of both radionuclides 1 d after contamination and decreasing fractions later on. Rinsing fruits removed up to 62% of the peel radionuclides. Further rinses and washes (plus detergent) of fruits showed that 134Cs had the same distribution in the outer skin as 85Sr and that the ratio of the two nuclides was close to the ratio in the contamination solution. This indicates that apple skin is a barrier not only to 85Sr, but probably also to 134Cs. Unaccounted for disappearance of radioactivity from fruits and leaves could have been a result of field losses of small superficial particles.