Bioaccumulation of 137Cs in wild mushrooms collected in Poland and Slovakia

Activities of caesium in the mushrooms collected at different localities in Poland and Slovakia have been compared. Discrimination factor, defined as [(Bq.kg 1 137Cs in caps)/(Bq.kg 1 40K in caps)]/[(Bq.kg 1 137Cs in stipes)/ (Bq.kg 1 40K 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