K-40, CS-134 AND CS-137 IN POLLEN, HONEY AND SOIL SURFACE-LAYER IN CROATIA

Specific activities of K-40, Cs-134 and Cs-137 in pollen, honey and in the first 25 cm of the surface soil layer were measured by gamma-spec trometry. Specific activity of K-40 in pollen is about 1 order of magn itude higher than in honey. A K-40 soil-to-pollen transfer coefficient (TC(K-40)) of 0.436 +/- 0.054 and a soil-to-honey transfer coefficien t TC(K-40) of 0.052 +/-0.008 were calculated as the mean of their resp ective values in 26 different segments of soil profile. Both parameter s have very stable values over time as well as through different segme nts of vertical soil profile. Cs-134 and Cs-137 specific activities in pollen and honey decrease with time, resulting in a decrease of Cs-13 7 soil-to-honey transfer factors (T(f)(Cs-137)) over time. The increas e of the soil-to-honey T(f)(Cs-137) with increasing soil depth is a co nsequence of vertical distribution of Cs-137 in soil. Soil-to-honey T( f)(Cs-137) values are highest in meadow and mixed honey types and lowe st in bush/tree honey. Similar trends are found for both T(f)(Cs-134) and T(f)(Cs-137). The results presented here indicate the importance o f the caesium inventory in soil segments where plant root systems are developed.