Measurement of Natural Radioactivity Levels and Evaluation of Radiological Hazard Risks in Areas of Eastern Coastline Sediments of Lake Hawassa in Ethiopia's Sidama Region

Natural radioactivity levels in the eastern coastline of Lake Hawassa sediment samples of Ethio-pia's Sidama Region have been measured. Sediment samples were collected and analyzed using gamma-ray spectrometery (high purity germanium detector) to evaluate the radioisotopes of 238U (214Pb, 214Bi), 232Th (228Ac, 212Pb), and 40K and their ranges of activity concentrations were 11.70 to 29.73 Bq kg-1, 19.01 to 58.61 Bq kg-1, and BDL to 827.21 Bq 1 kg- ,with average values of 16.51 +/- 1.20 Bq kg- 1 , 28.17 +/- 2.27 Bq kg-1 ,and 673.95 +/- 29.92 Bq kg- 1 (dry mass), respectively. The radiological hazard indices average values (radium equivalent (Req) (108.69 Bq 1 kg- ); hazard index (Hex (0.29); excess lifetime cancer risk (ELCR) (0.23 x 10-3 ); absorbed dose rate (DR) (52.70 nGyh-1 ); annual effective dose equivalent (AEDE) (0.07 mSv 1 yr- ); and annual gonadal dose equivalent (AGDE) (0.38 mSv yr- 1) were also evaluated and compared to the worldwide-recommended values. All results of radiological hazard indices obtained in this study were lower than their worldwide-recommended values were 370 Bq 1 kg- , <= 1, 59 nGy h- , 0.07mSv 1 1 yr- , 0.29 x 3 10- , and 0.3mSv yr-1 of radium equivalent activity, external hazard index, outdoor absorbed dose rate, outdoor annual effective dose equivalent, excess lifetime cancer risk, and annual gonadal dose equivalent, respectively. This suggests the eastern coastline of Lake Hawassa is safe from radioactive risk for aquatic species and various human activities, and appears as essential radiometric baseline information for further environmental monitoring programs.