Root uptake of radionuclides following their acute soil depositions during the growth of selected food crops.

Greenhouse experiments were performed to investigate the root uptake of radionuclides following their acute soil deposition during the growth of several food crops. For this purpose, the soil under the standing plants was contaminated without any direct contamination of their stems or leaves. The intention of this design was to differentiate foilar uptake and root uptake subsequent to a radionuclide deposition during the vegetation period. Soil-to-plant transfer of a radionuclide was quantified with its aggregated transfer factors specified for the time periods from deposition until harvest (T(ag)(a), m(2)kg(-1)). Deposition time-dependent T(ag)(a) values of Mn, Co, Sr and Cs for selected crop species were measured in an acid sandy soil. For rice and Chinese cabbage, HTO experiments were also carried out using this soil. Particularly for rice, experiments with various paddy soils were also performed for (90)Sr and (137)Cs. The obtained T(ag)(a) values varied considerably with the radionuclides, plant species, and times of deposition. Recommendations about, and limitations in, the use of the T(ag)(a) values were discussed.