Technetium-99 cycling in maple trees: characterization of changes in chemical form
Garten, C.T.; Lomax, R.D.
Health Physics 57(2): 299-307
1989
ISSN/ISBN: 0017-9078 PMID: 2547736 Document Number: 331003
Field studies near an old radioactive waste disposal site at Oak Ridge, Tenessee, had indicated that, following root uptake, metabolism by deciduous trees rendered 99Tc biogeochemically less mobile than expected. The form of Tc in sap, leaves, wood and leaf litter of Acer rubrum in the field and a small tree of A. saccharum transported to a greenhouse and labelled with 95mTc was characterized using dialysis, physical fractionation, chemical extraction, gel permeation chromatography, enzymatic extraction and TLC on silica gel. Analysis of the relative importance of free TcO4- and organically bound Tc indicated that there are multiple forms of Tc in Acer spp. Tc incorporated into wood occurred predominantly in soluble forms. In the leaf, Tc was converted to less soluble forms that were apparently associated with structural components of cell walls. This conversion could explain why 99Tc is not leached easily by rainfall from tree foliage and why it appears to accumulate in leaf litter layers at the Oak Ridge study site.