| Abstract | A variety of mushrooms and soils collected in Japan was analyzed for 137Cs, 134Cs and 4°K. The levels of l37Cs in mushrooms (167 samples belonging to 79 species) varied very widely ranging from < 2 to 16000 Bq/kg on a dry weight basis, while those of 4°K were relatively constant. The median concentrations of 137Cs and 4°K were 44 and 1100 Bq/kg (dry wt), respectively. In many samples, concentrations of 134Cs were under the detection limit (usually < 5 Bq/kg, dry wt). In order to determine thefactors controlling the radiocesium concentration, 65 mushroom samples collected from a selected area were categorized under four different groups according to the main habitat of their mycelia, i.e. wood, litter layer, surface soil layer (0-5 cm) and the following soil layer ( > 5 cm). The third group of mushrooms (surface soil layer) showed the highest average concentration of t37Cs, which might reflect its high concentration in the surface soil layer. Habitat of mycelium seemed to be one of the most important factors controlling radiocesium concentration in mushrooms. Average soil-mushroom transfer factors of each group were in the range of 5.5-13. |
