Modeling the potential role of a forest ecosystem in phytostabilization and phytoextraction of 90Sr at a contaminated watershed

The behavior of Sr-90 at forest sites in the White Oak Creek watershed, near Oak Ridge, Tennessee, was simulated with a simple, site-specific, multicompartment model that linked biomass and element cycling dynamics. The model was used to predict the role of forest cover in mitigating hydrologic losses of Sr-90 from contaminated soils (i.e. phytostabilization) under conditions where contaminant transport is governed mainly by shallow subsurface flow. The model was also used to predict the removal of Sr-90 from soil (i.e. phytoextraction) through the growth and hal vest of short rotation woody crops over a period of 30 years. Simulations with the model indicated that (1) forest preservation on the watershed is a form of phytostabilization because forest cover helps to minimize hydrologic losses of Sr-90 and (2) an attempt to significantly reduce amounts of Sr-90 in soil through phytoextraction would be unsuccessful. Over a period of 30 years, and under various management strategies, the model predicted that similar to 15% of the Sr-90 initially present in soil at a contaminated site was lost through hydrologic transport and similar to 53% was lost by radioactive decay, Phytostabilization may be important in the management of radioactive land when issues like waste minimization and pollution prevention affect the selection of technologies to be used in environmental restoration. (C) 1999 Elsevier Science Ltd. All rights reserved.