TC-99 CYCLING IN DECIDUOUS FORESTS - REVIEW AND ECOSYSTEM MODEL DEVELOPMENT

This paper presents a model to summarize information on the fate of technetium-99 (**9**9Tc) in a woodland site amidst an old radioactive waste disposal area in the eastern United States. Rate constants for **9**9Tc transfer between the biological and physical components of the forest have been derived based on field measurements and associated laboratory studies. The fate of **9**9Tc in the woodland occupying the drainage area immediately adjacent to the disposal site was simulated with the derived rate constants and some assumptions about relative inputs to and outputs from the surface soil available pool in the model forest. A steady state in the distribution of **9**9Tc among soil compartments and forest compartments was reached in simulations after 30 years of continuous input to the soil available pool. Study results and applications are discussed.