137Cs and 40K in Cortinarius caperatus mushrooms (1996–2016) in Poland - Bioconcentration and estimated intake: 137Cs in Cortinarius spp. from the Northern Hemisphere from 1974 to 2016

Cortinarius caperatus grows in the northern regions of Europe, North America and Asia and is widely collected by mushroom foragers across Europe. This study shows that in the last three decades since the Chernobyl nuclear accident, C. caperatus collected across much of Northern Poland exhibited high activity concentrations of radiocaesium (137Cs) - a long-lived radionuclide. The mushroom appears to efficiently bioconcentrate 137Cs from contaminated soil substrata followed by sequestration into its morphological parts such as the cap and stipe which are used as food. The gradual leaching of 137Cs into the lower strata of surface soils in exposed areas are likely to facilitate higher bioavailability to the mycelia of this species which penetrate to relatively greater depths and may account for the continuing high activity levels noticed in Polish samples (e.g. activity within caps in some locations was still at 11,000 Bq kg−1 dw in 2008 relative to a peak of 18,000 in 2002). The associated dietary intake levels of 137Cs have often exceeded the tolerance limits set by the European Union (370 and 600 Bq kg−1 ww for children and adults respectively) during the years 1996–2010. Human dietary exposure to 137Cs is influenced by the method of food preparation and may be mitigated by blanching followed by disposal of the water, rather than direct consumption after stir-frying or stewing. It may be prudent to provide precautionary advice and monitor activity levels, as this mushroom continues to be foraged by casual as well as experienced mushroom hunters

Migration of radiocaesium in individual parts of the environment

The aim of this study was to compare the amount of radiocaesium in chosen compartments of environment in two localities of Košice vicinity (Košice and Jasov). Prevailing part of radiocaesium is in the upper layer of soils and specific activity of 137Cs in the first layer for locality Jasov in 2001 achieved 21.49 Bq.kg 1. Transfer factor values estimated for mixed grasses and for individual years varied within the range of 0.22 to 0.56 at locality Košice and of 0.09 to 0.19 at locality Jasov. On the base of results from modified Tessier sequential extraction method we determined that more than 50% of this radionuclide is in the soil in not extractable fraction. From studied species of mushrooms in sample of Rozites caperata the specific activity achieved 1822.0 Bq.kg 1 d.w

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 bioindicator