Radioecology studies in the vicinity of a closed uranium mine

Although the influential area of the former uranium mine at Zirovski vrh, Slovenia has been under continuous radiological monitoring, more detailed radioecology studies, focused on assessing mobility and bioavailability of deposited radionuclides, were initiated about five years ago. The mobility of 238U, 234U, 230Th and 226Ra was studied applying two sequential extraction protocols. The results revealed that both sequential extraction protocols are not comparable as the data obtained are protocol- and radionuclide-dependent. It was found that the most mobile ones were uranium isotopes, followed by 226Ra and 230Th. In addition, uptake of particular radionuclides by the wetland plants (Molinia arundinacea, Juncus effusus and Caltha palustris) grown in soils contaminated with seepage waters from the tailings was studied. The plants contained higher levels of 238U, 226Ra and 230Th compared to the plants from the control site. Activity concentration of 226Ra was the highest for all three plant species. Activity concentration of natural radionuclides in milk collected from the area of Zirovski vrh was comparable to the reference location, except for uranium where the content was higher. The combined annual effective dose for adults consuming milk from the Zirovski vrh area is 13 ± 2 μSv yr−1

Distribution of natural and artificial radionuclides in chernozem soil/crop system from stationary experiments

n The present paper focuses on the determination of radiological characteristics of cultivated chernozem soil and crops from long-term field experiments, taking into account the importance of distribution and transfer of radionuclides in the soil-plant system, especially in agricultural cropland. The investigation was performed on the experimental fields where maize, winter wheat, and rapeseed were cultivated. Analysis of radioactivity included determination of the gross alpha and beta activity as a screening method, as well as the activities of the following radiouclides: natural (Pb-210, U-235, U-238, Ra-226, Th-232, K-40, Be-7) and artificial (Sr-90 and Cs-137). The activities of natural and artificial (Cs-137) radionuclides were determined by gamma spectrometry, while the artificial radionuclide Sr-90 was determined by a radiochemical analytical method. Based on the obtained results for the specific activity of K-40, Cs-137, and Sr-90, accumulation factors for these radionuclides were calculated in order to estimate transfer of radionuclides from soil to crops. The results of performed analyses showed that there is no increase of radioactivity that could endanger the food production through the grown crops