Uptake and transport of radioactive cesium and strontium into strawberries after leaf contamination

Abstract

Radioactive cesium was quickly taken up by the leaves of strawberry plants. Eight weeks after foliar application about 90 % of the total recovered radioactive isotope Cs-134 was incorporated into the plant.The other 10 % was not taken up and could be washed off the leaves. Until that time 75 % Of the total recovered cesium activity was transported from the leaves to other plant organs, while 15 % stayed in the leaves. Forty-four percent of the transported activity was transferred to the berries and 22 % to other organs. Three percent was detected in the daughter plants and 6 % was found in the pot soil. In the same period only 44 % of the total recovered strontium was detected in the treated and washed leaves. Less than 10 % was found in the untreated plant parts and soil. Neither fruit, runner plants nor roots contained any radioactive strontium at this time. Since activity was detected in the roots only at the very beginning of the experiment, the strontium detected in the soil could have been introduced by contamination. Most of the strontium taken up by the leaves was stored in these organs. The danger that radioactive cesium, liberated by a nuclear incident, will be taken up by leaves of food plants and transported into the edible parts is real and is, in an initial phase, substantially greater than the danger of an uptake by the roots, because cesium in the soil is fixed by certain clay minerals. With strontium the danger of redistribution from radioactive contaminated leaves into other plant organs is small. However, the possibility of contamination of edible plant parts with radioactive strontium from the soil, transported in the xylem from the root to the shoot, is real.