¹³⁷Cs in mushrooms from Croatia sampled 15-30 years after Chernobyl

The aim of this study was to select species with higher potential to accumulate ¹³⁷Cs among the available mushroom species, by determining the activity concentrations of ¹³⁷Cs in mushrooms collected along north and north-western part of Croatia. A total of 55 samples of 14 different species were analyzed and the potential of mycorrhizal and saprotrophic species to accumulate ¹³⁷Cs was compared. A wide range of the dry weight activity concentrations of ¹³⁷Cs was detected, ranging from 0.95 to 1210 Bq/kg (154 Bq/kg mean value; 52.3 Bq/kg geometric mean) in mycorrhizal and 1.05-36.8 Bq/kg (8.90 Bq/kg mean value; 5.49 Bq/kg geometric mean) in saprotrophic species. Statistical analyses showed that mycorrhizal species accumulate significantly higher concentrations of ¹³⁷Cs and thus could perform better as long-term bioindicators of environmental pollution by radiocaesium then saprotrophic species. The comparison of Boletus sp. and Hydnum repandum (both mycorrhizal species commonly found in Croatia) showed, in general order of magnitude, higher accumulation in Hydnum repandum. Clearly, mushrooms, especially mycorrhizal species, can be used as significant indicators even decades after the occurrence of any serious ¹³⁷Cs contamination event. However, as a wide range of values indicates that various parameters may influence the total uptake of the ¹³⁷Cs into the mushroom fruit bodies, it is necessary to emphasize that ¹³⁷Cs activity detected in a single mushroom sample is very site-specific.