Mosses in the Kopački Rit Nature Park, Croatia, as bioindicators of a potential radioactive contamination of the middle Danube River basin

We studied activity concentrations of radionuclides in the Kopački Rit Nature Park using mosses as bioindicators. This area of intact nature is at the tripoint of Croatia, Hungary, and Serbia, being located basically at the centre of the middle Danube River basin. Therefore, it can be easily affected by airborne pollution from various locations in the Middle Europe and beyond. The goal of our research was to assess whether the Park could serve as a location where any new radioactive contamination could be sensitively detected, which implied a necessity for low activity concentrations at the present time. Our gamma-ray spectrometry revealed the presence of only one anthropogenic gamma emitter, that is, (137)Cs. Its activity concentration in the mosses ranged from 0.7 to 13.1 Bq kg(−1), being low indeed. Another radionuclide in our focus was (210)Pb. Generally, its elevated concentrations may signify ecologically undesirable human activities that involve naturally occurring radioactive matter. The activity concentration of (210)Pb in the mosses was in the range from 183 to 690 Bq kg(−1). This did not depart from the results of other similar studies and was again low enough for a detection of possible excess amounts of this radionuclide in the future.