USING SYSTEM DYNAMICS TO MODEL CESIUM PARTITIONING IN THE RHIZOSPHERE

摘要

System Dynamics modeling is used to predict cesium (Cs) partitioning betweenbound, aqueous, and phytoextracted phases in the rhizosphere. The model categorizesprocesses that impact Cs fate into six sub-models. A seventh sub-model describes Csflux between the three phases. Functional relationships and parametric values weredeveloped based on literature, field, and laboratory data. Sensitivity analyses wereconducted to evaluate the effects of root exudates on Cs partitioning, and the effects ofroot density, aerial plant density, potassium requirement/concentration, sodiumconcentration, and moisture content on root exudates and Cs partitioning. An increase inroot exudate concentration results in a decrease in the bound Cs concentration andincrease in the aqueous and phytoextracted Cs concentrations. Although the otherparameters affect Cs partitioning partly according to how they affect root exudates, thecomprehensive nature of the system complicates the overall effect.