Dynamics of the factors of 137Cs transfer to natural and sown grasses in the long term after the accident at the Chernobyl power plant

The regularities of changes in factors of 137Cs transfer to natural and sown grasses in the longterm period after the Chernobyl accident are described. The dynamics of changes in factors of 137Cs transfer to sown grasses over the period of 1993 to 1999 was of a non-uniform character. On average, these transfer factors (TF) tended to decrease in that period. A significant tendency for an increase in TF to sown grasses was noted for 1997-1999. The half-life periods of decrease in TF to natural grasses in the period 1993-1999 were shown to be ranged from 4.6 to 24.6 years. It was demonstrated that the differences in the TF dynamics between sown and natural grasses were related to the peculiarities of their development and application of countermeasures.