Assessment of radioactivity levels and associated radiological hazards index in lake water from eastern areas of Lake Hawassa, Sidama region, Ethiopia

Abstract Water samples from the Sidama Region of Ethiopia's Lake Hawassa have been measured for naturally occurring radioactivity. The radioisotopes of 238U (214Pb, 214Bi), 232Th (228Ac), and 40K were assessed on water samples through the use of gamma-ray spectrometry (a high-purity germanium detector). The activity concentrations (in Bq (Bq)) of these isotopes ranged from BDL to 4.17 ± 0.82, BDL to 9.13 ± 1.06 , and BDL to 92.10 ± 4.50, with average values of 2.35 ± 0.58, 6.05 ± 0.58 , and 55.13 ± 2.80 , respectively. In addition, the average values of the radiological hazard indices: external hazard index (= 0.04), absorbed dose rate ( = 7.14 nGy), and annual effective dose equivalent ( = 0.009 mSv) were assessed and compared to different countries and an international standard. According to literature from different countries, these findings of all activity concentrations and radiological hazard indices (the external hazard index, absorbed dose rate, and annual effective dose equivalent) fall within that range. It also appears to be baseline data that will facilitate ongoing assessments and comparisons of radiological safety in various environments. By establishing a reference point, it can help identify changes or trends over time, guiding future environmental policies and initiatives.