Radiocaesium in Cortinarius spp. mushrooms in the regions of the Reggio Emilia in Italy and Pomerania in Poland

Activity concentrations of 134Cs and 137Cs have been determined in 23 species of mushrooms of the genus Cortinarius (59 individual samples) collected from the Reggio Emilia in Italy 1992-1999 and in 4 species (16 composite samples and 413 individuals) from the Pomerania region in Poland from 1996 to 2015. Across all the Cortinarius species from the Reggio Emilia, the activity concentrations were relatively high in Cortinarius alboviolaceus, Cortinarius duracinus, Cortinarius orellanus, Cortinarius rapaceus, and Cortinarius subannulatus, in which 137Cs was at 10,000 ~ 100,000 Bq kg-1 dry biomass (db) in 1994. Smaller activity concentrations were found in Cortinarius bivelus, Cortinarius bulliardii, Cortinarius cotoneus, Cortinarius largus, Cortinarius lividoviolaceus, Cortinarius purpureus, Cortinarius rufo-olivaceus, Cortinarius torvus, and Cortinarius venetus with levels at 1000 ~ 6000 Bq kg-1 db from 1992 to 1994, and further in Cortinarius anserinus, Cortinarius auroturbinatus, C. largus, Cortinarius praestans, Cortinarius purpurascens, Cortinarius scaurus, Cortinarius sebaceous, Cortinarius talus, and Cortinarius variecolor with activity concentrations at 100 ~ 600 Bq kg-1 db in 1994. All the data were calculated for dehydrated fungal material corrected back to the exact date samples of collection. The greatest activity concentrations of 137Cs both in Italy (1992-1999) and Poland (1996-2010) were found in the popular Cortinarius caperatus, confirming its very high capacity of radiocaesium accumulation. Besides 137Cs, the isotope 134Cs was detected in some species from the Reggio Emilia. An average calculated ratio of activities of 134Cs to 137Cs referenced to 1986 was equal to 0.38 in mushrooms from the Reggio Emilia, and this value slightly differ from that specific for Chernobyl fallout, which was 0.54. It was calculated that 137Cs originating from Chernobyl accident constituted about 68 % of the total activity concentration of the isotope in Reggio Emilia in 1986, while as much as 32 % of 137Cs in mushrooms were from the global fallout from nuclear bomb testing.