Variability of Transfer Factors of 90Sr in Herbaceous Plants of Different Taxonomic Groups in the Nuclear Facility Impact Zone

The variability of 90Sr aggregated transfer factors (Tag) was studied in herbaceous plants of different taxonomic affiliations, whose populations have been present in the impact zone of a major nuclear plant in the Urals for more than 65 years. The primary contamination of the area occurred during the initial period of the enterprise’s operation (1949–1957) due to inadequate methods of handling radioactive waste: (1) multiple discharges into the Techa River; (2) explosion of a radioactive waste storage tank (Kyshtym accident). Currently, the range of 90Sr Tag values for 54 herb species belonging to 20 families and 2 classes ranges from (0.8−140.0) × 10–3 m2 kg–1. The accumulation of 90Sr by plants is primarily determined by their species-specific characteristics and depends to a lesser extent on their affiliation with higher taxonomic groups. Furthermore, the variability of 90Sr Tag in individual plant species was influenced by a combination of soil physicochemical properties, radioactive contamination heterogeneity, and weather-climatic factors specific to different growing seasons. It was established that the relationship between 90Sr Tag in herbaceous plants and soil contamination density follows a power function under conditions of landscape element homogeneity and soil type similarity.