Assessment of radiation exposure from naturally occurring radioactive materials in Bahi district, Tanzania, using RESRAD-BIOTA modeling

This study presents modeling of dose rates using the RESRAD-BIOTA code (version 1.8) for natural radioactivity levels in the terrestrial environment of Bahi District, Tanzania. Modeling of biota dose rates is important in predicting ecological risk and suggesting environmental protection measures. Non-human biota dose rates were modeled on previously reported soil radioactivity concentrations of 238U, 226Ra, 232Th, and 40K. The model utilized weighted means of the data, statistically justified under the assumption of a spatially homogeneous radioactivity distribution. Statistical test indicated significant spatial homogeneity (p < 0.05) with 232Th and 40K radionuclides as major contributors to the total dose rates. Principal Component Analysis (PCA) output showed a high positive correlation between 226Ra and 232Th and a slightly weak correlation with 40K. The overall total dose rates for radiation exposure due to the selected radionuclides, assessed using Tier 1, were approximately 8.9 µGy h− 1 and 8.5 µGy h− 1 for the reference terrestrial animal and plant, respectively. The RESRAD-BIOTA Level 3 modeled 10 animal species representatives of the study area. The total dose rates were approximately 7.5 µGy h− 1 and 5.8 µGy h− 1 for large mammals and small animals, respectively. Large mammals and small animals were exposed 25% and 42%, respectively, less than 10 µGy h− 1 reference level for wildlife. The obtained results suggest no significant radiation exposure and indicate minimal radiological risk under current environmental conditions. However, continuous monitoring is recommended for sites with elevated radioactivity concentrations before any major prospective land exploitations.