Modeling Radiocesium Dynamics in a Contaminated Forest in Japan

Abstract

For the management of radionuclide contamination in a forest, a dynamic model for 137Cs was developed applying previous study models and using explicit measured data in Fukushima area. The transfer of 137Cs among organic layer, surface soil, and parts of trees was estimated in deciduous broad-leaved (konara; Quercus serrata) forest and evergreen coniferous needle-leaved Japanese cedar (sugi; Cryptomeria japonica) forest. Barks in both of the forest and surface of leaves were utilized as one of the compartments in this model because of the surface deposition of 137Cs and the 137Cs infiltration from the surfaces. Monte Carlo method was applied to optimize the best set of parameter values for mathematical equations, which control 137Cs transfer between the compartments. The model estimates well fit to the observed data at konara and sugi stands in one place, but did not fit to that of both stands in another place because of the difference in concentration in wood part of both tree species.