NUKLEONIKA 2005, 50(Supplement 1):S15-S18

Activities of caesium in the mushrooms collected at different localities in Poland and Slovakia have been compared. Discrimination factor, defined as [(Bq kg^{-1 137}Cs in caps)/(Bq kg^{-1 40}K in caps)]/[(Bq kg^{-1 137}Cs in stipes)/(Bq kg^{-1 40}K in stipes)], was used to explain mechanisms of uptake and transport of radiocaesium in fungi. The collected specimens were divided into caps and stipes. Activities of ¹³⁷Cs and ⁴⁰K were measured using a multichannel gamma spectrophotometer with HPGe(Li) detector. The highest accumulation of ¹³⁷Cs was found in the samples of Xerocomus badius, Suillus luteus and Tricholoma equestre (2.7, 1.9 and 1.2 kBq kg^-1, respectively). T. equestre and S. luteus proved to hyperaccumulate caesium since ¹³⁷Cs levels in the caps were two orders of magnitude higher than in the soil while only one order higher in the case of X. badius. Transport of ¹³⁷Cs from stipe to cap in fruitbody is directly related to K concentration with lack of similar dependence in the case of transport from soil to cap. There is no dependence between activity of ¹³⁷Cs in the analyzed fruitbodies and its activity in the soil, which makes mushrooms controversial bioindicators of ¹³⁷Cs-pollutted soils.