Retention and translocation of foliar applied ~(239,240)Pu and ~(241)Am, as compared to ~(137)Cs and ~(85)Sr, into bean plants (Phaseolus vulgaris)

摘要

Foliar transfer of ~(241)Am, ~(239,240)Pu, ~(137)Cs and ~(85)Sr was evaluated after contamination of bean plants (Phaseolus vulgaris) at the flowering development stage, by soaking their first two trifoliate leaves into contaminated solutions. Initial retentions of ~(241)Am (27%) and ~(239,240)Pu (37%) were higher than those of ~(137)Cs and ~(85)Sr (10-15%). Mean fraction of retained activity redistributed among bean organs was higher for ~(137)Cs (20.3%) than for ~(239,240)Pu (2.2%), ~(241)Am (1%) or ~(85)Sr (0.1%). Mean leaf-to-pod translocation factors (Bq kg~(-1)dry weight pod/Bq kg~(-1)dry weight contaminated leaves) were 5.0 X 10~(-4) for ~(241)Am, 2.7 X 10~(-6) for ~(239,240)Pu, 5.4 X 10~(-2) for ~(137)Cs and 3.6 X 10~(-4) for ~(85)Sr. Caesium was mainly recovered in pods (12.8%). Americium and strontium were uniformly redistributed among leaves, stems and pods. Plutonium showed preferential redistribution in oldest bean organs, leaves and stems, and very little redistribution in forming pods. Results for americium and plutonium were compared to those of strontium and caesium to evaluate the consistency of the attribution of behaviour of strontium to transuranium elements towards foliar transfer, based on translocation factors, as stated in two radioecological models, ECOSYS-87 and ASTRAL.