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-spectrometry. Specific activity of K-40 in pollen is about 1 order of magnitude 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 coefficient TC(K-40) of 0.052 +/-0.008 were calculated as the mean of their respective values in 26 different segments of soil profile. Both parameters have very stable values over time as well as through different segments of vertical soil profile. Cs-134 and Cs-137 specific activities in pollen and honey decrease with time, resulting in a decrease of Cs-137 soil-to-honey transfer factors (T(f)(Cs-137)) over time. The increase of the soil-to-honey T(f)(Cs-137) with increasing soil depth is a consequence 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 lowest 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 of the caesium inventory in soil segments where plant root systems are developed.