Abstract
The degree of contamination of wheat, potato, cabbage and sugar beet has been investigated after the application of Sr89 and Cs137 in a fine spray at different stages in the growth of the plants. The main experimental treatments were applied over two years to obtain information on seasonal effects. The extent to which Cs137 was concentrated in the edible tissues greatly exceeded that of Sr89. Usually the concentration of Sr89 or Cs137 in each crop varied by less than an order of magnitude irrespective of the state of growth of the crop at the time of contamination and the year in which the experiment was carried out; the Sr89 content of wheat grain, however, was considerably lower when the plants were contaminated before the ears emerged. A large part of the radioactivity which was deposited on the leaves was removed rapidly by rain; a further fraction was lost as leaves died. The data obtained have been used to predict the probable degree of contamination of crops growing under normal agricultural conditions.