Abstract
The transfer of Cs-137 and Sr-85 from fallout to plants was studied in two successive pot experiments. Five plant species (Oryza Sativa, Tritichum Vulgares, Vicia Faba, Sesamum Orientale and Trifolium Alexandrinum) were grown in pots containing sandy clay loam soil. For simulating foliar contamination, radioactive Cs-137 and Sr-85 solutions were sprayed once with different activity concentrations gently on the shooting system. After 8 weeks of radioactivity application to the above first four plants and 4 weeks to the last one, the total absorption of Cs-137 and Sr-85 and their distribution in different parts of the tested plants were determined. Most of the absorbed Cs-137 and Sr-85 accumulated in shoots with proportions ranged from 70.8 to 81.9% and from 88.9 to 95.0%, respectively for different plants. The absorbed Cs-137 and 85Sr by grains/seeds followed that of shoots with values ranged from 11.9 to 19.2% and from 5 to 10.9%, respectively. The percentage of Cs-137 absorbed by roots ranged from 6.2 to 10.0% among different plants, while Sr-85 in roots of plants was below the minimum detectable activity of the detector. For Trifolium, most of the absorbed Cs-137 and Sr-85 accumulated in the first harvest (81.9 and 98.6%). The aggregated transfer factors (Tag) of both radionuclides under foliar conditions were to a great extent similar. The average values of Tag factors (m(2)kg(-1)) of 137Cs and Sr-85, respectively, in rice grains were 3.4 x 10(-4) and 1.6 x 10(-4); in wheat grains were 4.2 x 10(-4) and 2.1 x 10(-4); in bean seeds were 4.9 x 10(-4) and 2.6 x 10(-4); and in sesame seeds were 2.8 x 10(-4) and 1.2 x 10(-4). Those Tag factors of grains/seeds were substantially lower than those obtained with straw of the corresponding plant species.