Ion competition effects on the selective absorption of radionuclides by komatsuna (Brassica rapa var. perviridis)

The selective absorption coefficient, which is a parameter of an uptake mod el of radionuclides by plants, was determined for various radionuclides by a multitracer technique. Komatsuna, Brassica rapa var, perviridis, was hydr oponically cultivated in a nutrient solution containing a multitracer for 1 day. Nutrient concentration dependence of the selective absorption coeffic ient of various elements from Be to Re was obtained separately for leaves a nd roots. The selective absorption coefficients of these elements were, in general, found to decrease with an increase in the concentration of nutrien t solutions. Regression equations of the power function for the selective a bsorption coefficients and the concentration of nutrient solutions were obt ained for the leaves and roots. The effects of photon flux and growth stage of plants on the selective absorption coefficients were also studied. It w as found that the photon flux influenced the accumulation of radionuclides in the roots but had no significant effect on the selective absorption coef ficients for the leaves in 1-day cultivation with the multitracer. The sele ctive absorption coefficients of Mn and Zn in the leaves of the plants at t he development stage were higher than those at the maturation stage. For th e other elements, no significant effects of the growth stage on the selecti ve absorption coefficients were observed. (C) 1999 Elsevier Science B.V. Al l rights reserved.