40K, 134Cs and 137Cs in pollen, honey and soil surface layer in CroatiaD. Barisica, K. Lazarica, S. Lulica, A. Vertacnika, M. Drazicb and N. Kezicb
a Center for Marine Research, Ruder Boskovic Institute, Bijenika 54, 41000 Zagreb, Croatia
b Agricultural Faculty, Svetos imunska 25, Zagreb, Croatia
Abstract - Specific activities of 40K, 134Cs and 137Cs in pollen, honey and in the first 25 cm of the surface soil layer were measured by gamma-spectrometry. Specific activity of 40K in pollen is about 1 order of magnitude higher than in honey. A 40K soil-to-pollen transfer coefficient (TC( 40K)) of 0.436 ± 0.054 and a soil-to-honey transfer coefficient TC(40K) 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. 134Cs and 137Cs specific activities in pollen and honey decrease with time, resulting in a decrease of 137Cs soil-to-honey transfer factors (Tf(137Cs)) over time. The increase of the soil-to-honey Tf(137Cs) with increasing soil depth is a consequence of vertical distribution of 137Cs in soil. Soil-to-honey T f(137Cs) values are highest in meadow and mixed honey types and lowest in bush/tree honey. Similar trends are found for both Tf(134Cs) and Tf(137Cs). The results presented here indicate the importance of the caesium inventory in soil segments where plant root systems are developed.
Key words: potassium / caesium / honey / pollen / soil / transfer factor / radioactive contamination