Soil-to-plant transfer factors for natural radionuclides in grass in the vicinity of a former uranium mine

The activity concentrations of 238U, 230Th, 226Ra and 210Pb were determined in soil and grass samples collected from sites at the uranium mill tailings waste pile, which lies near the former uranium mine at Žirovski vrh in Slovenia. Soil-to-plant transfer factors were determined and the potential use of grass as a monitor of radionuclide migration from the waste pile was evaluated. It was found that grass was not suitable for monitoring 230Th and 210Pb migration (no linear correlation between soil and grass activity concentrations) but has potential in predicting 238U and 226Ra migration (linear correlation between soil and grass activity concentrations). Soil-to-plant transfer factors for grass were in the range from 0.0014 to 0.015 kg/kg DM for 238U, 0.0039 to 0.012 kg/kg DM for 230Th, 0.035 to 0.46 kg/kg DM for 226Ra and 0.098 to 1.5 kg/kg DM for 210Pb.