Bioindicators are living organisms that are successfully used for monitoring changes in the environmental health due to natural and/or anthropogenic influences. Dragonflies (Odonata) are considered to be good indicators of water quality; however, research on dragonflies as potential indicators of radioactivity is scarce. The aim of this study was to evaluate dragonflies as potential biological indicators of ionising radiation in nature by measuring 137Cs activity concentrations in the dragonfly and river water samples. Altogether, 11 collective samples of dragonflies were collected from the bank of the Mura-Drava-Danube Biosphere Reserve, in the area of Virovitica-Podravina County. Following the initial sample preparation, the gamma spectrometry technique, employing an ORTEC HPGe detector system, was utilised to determine the activity concentrations of 137Cs. The results show that the activity concentrations of 137Cs in the river water were in the range from 4 to 13 Bq/m3. The results of dragonfly samples showed that 137Cs was in the range from 1.7 to 3 Bq/kg. This was more than a hundred times higher than in the river Drava water. According to the obtained results, we conclude that dragonflies could be used as potential bioindicators of radioactivity.
Keywords: Cs-137; Dragonfly; bioindicators; gamma-ray spectrometry; radiation.