Assessment of Natural Radioactivity Level and Associated Radiological Risk in Ground-water samples from Hakim Gara Quarry Area, Ethiopia

Abstract

Radiological hazards could arise from high amount of radionuclides in food and water when ingested unless investigation is conducted. Radioactivity levels in water needs investigation especially if the groundwater supply is used for domestic consumption. In this study, radioactivity levels of long-lived naturally occurring Radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K were measured from water samples of six groundwater collected from areas closer to Harar town around Hakim Gara quarrying site. Gamma spectroscopic system of High Purity Germanium (HPGe) detector was employed to determine radioactivity level and to assess the radiological impacts imposed to the public. The measured values were ranging from 1.9 Bq.L^-1to 3.0 Bq.L^-1 with mean of 2.7±0.4 Bq.L^-1 for ²³⁸U, from 7.7 Bq.L^-1 to 9.3 Bq.L^-1 with mean of 8.1±0.9 Bq.L^-1 for ²³²Th and from 71.2 Bq.L^-1 to 104.9 Bq.L^-1 with mean of 87.9±11.4 Bq.L^-1 for ⁴⁰K. The radiological health risk assessments H_ex, H_in, D_g, Annual Effective Dose Equivalent (AEDE) and Excess Lifetime Cancer Risk (ELCR) were calculated and their mean values were 0.057±0.002 for H_ex, 0.064±0.003 for H_in, 9.76±0.35 nGyh^-1 for D_g, 0.06±0.002 mSv.y^-1 for AEDE and 0.021±0.008 x10^-3 for ELCR. From radiological point of view, based on the findings of measurements analyzed in samples of this study, the groundwater of the study area is safe to use for domestic purpose. The results obtained in this study could contribute as input for the national database and enable to conduct further studies in the future.