Small mammals as appropriate radioecological monitor species in Alpine ecosystems: total β-activity as an indicator of decreasing consequences of the Chernobyl accident

The importance of Alpine ecosystems is increasing due to the influence of a wide number of ecological factors. Atmospheric attenuation of solar radiation, particularly in the ultraviolet spectra, is decreasing, leading to higher surface exposure and higher doses in plants and diurnal animals. At the same time, exposure to man-made radionuclides in the high mountains in Europe is decreasing due to the radioactive decay of anthropogenic radioisotopes, as well as the sedimentation and de-mobilization of heavier elements, which reduce exposure of the Alpine biota to technogenic emitters. The current article is based on biomonitoring studies of wild small mammals, conducted on Rila Mountain in the period 1993-2020. Total β-activity was measured with the use of a low-background beta counter (LAS 3A level activity system with 30% efficiency on 40K). A reduction by a factor of 10 was observed over a two-decade time period, attributable in part to the decay of deposited anthropogenic β-emitters after the Chernobyl accident in 1986. The highest reduction was observed in Apodemus sp., the least – in the herbivorous vole Myodes glareolus, indicating the high potential of the latter species as a zoomonitor of residual radioactive contamination. The comparative utility of several rodent taxa: Apodemus species, and two representatives of the subfamily Arvicolinae: M. glareolus and Chionomys nivalis and insectivorous Sorex araneus is discussed in the context of the radioecological biomonitoring of high mountain ecosystems. Finally, the study is put in the global context of climate change and overall increased anthropogenic pressure, affecting other ecosystems such as tundra and boreal forests.