engleski

DIFFERENT FOOD ITEMS AS POSSIBLE BIOINDICATORS OF SEASONAL TREND OF RADIONUCLIDES IN LARGE PREDATORS

Bioaccumulation of radionuclides in terrestrial food-web has been recorded all over the Europe, most of all with 137Cs after the Chernobyl accident in 1986, which is the main anthropogenic environmental contaminant threat and can pose a public health problem. The aim of this study was to investigate 137Cs and 40K load in large predators in the mountain forest region of Gorski Kotar, Croatia, a quarter of century after the Chernobyl accident. 137Cs and 40K activities were determined by the gamma-spectrometric method in 47 brown bears (Ursos arctos), 7 wolves (Canis lupus) and 1 lynx (Lynx lynx) meat samples. Moreover, 63 samples of different food items for the studied carnivore species as well as 27 soil samples were collected in the study area as well. All loads of 137Cs in analysed samples were found at levels significantly below the statutory values of 600 Bqkg-1. The highest caesium concentration in brown bear was detected in a 5-year old male (body mass of 168 kg), culled on 19 April 2013 (132  13.8 Bqkg-1), and the lowest in 10-year old male (body mass of 209 kg), culled on 15 April 2013 (0.937  0.602 Bqkg-1). It was demonstrated that caesium concentration in brown bears appeared to be higher in spring then in autumn/winter season. Effective decade half-time calculated for brown bears in analysed interval from 2012 to 2014 was 3.649 years. Caesium concentration in seven wolves’ samples varied between 0.225 Bqkg-1 and 22.2 Bqkg-1, with the highest activities recorded in two wolves’ puppies. The highest caesium concentration (153  15.9 Bqkg-1) of all large predator samples was detected in 2-year old female lynx (body mass of 12.5 kg), killed in road accident on 13 October 2013. A wood hedgehog (Hydnum repandum), with a 137Cs load ranged between 21.7 and 562 Bqkg-1, seems to be the best bioindicator mushroom species considering caesium pollution. Among plant species, blueberries (Vaccinium myrtillus) represent a food item with potentially higher caesium uptake (228 Bqkg-1) for brown bears in our studied area. Transfer factor TF “soil to food items” expressed as a percentage for caesium and potassium ranged from 0.002 to 5.166 and from 0.443 to 5.865, respectively. Intensive consumption of some mushrooms and berries may be a significant source of caesium ingestion by brown bear in the Gorski Kotar region. However, further investigation is necessary to better illuminate the issue of radionuclide pollution and to determine the dominant sources of caesium for other large predator species.

137Cs; 40K; Ursus arctos; Canis lupus; Lynx lynx; mountain forest ecosystem

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