Contamination of Plant Follage with Radioactive Fallout

Studies of foliage contaminated with fallout from nuclear detonations showed that fallout particles less than 44 mu diameter were selectively trapped in the hnirs and crevices and on resinous glands of the leaf surfaces. The beta activity from fallout lodged on plant foliage was correlated with the beta activity from fallout particles less than 44 mu diameter which were deposited downwind from the nuclear detonations. Although decontamination treatments did not remove all fallout particles from plant foliage, the levels of radioactivity which remained were less than half of the original after washing with mild detergents and chelating agents. Fallout on plant foliage that originated from towersupported detonations was 5 to 35% soluble in 0.1 N HCl; fallout from balloon-supported detonations was 60 to 90% soluble. Radioisotopes of cerium, yttrium and zirconium contributed about 60% of the beta activity found in smaller than 44 micron-diameter fallout particles (90 days after detonation); radiostrontium accounted for nearly 5% and radiocesium contributed less than 1%. (auth)