ASSESSMENT OF RADIOACTIVITY LEVEL AND ASSOCIATED RADIOLOGICAL HAZARD FOR THE SEDIMENT SAMPLES OF RIVERBED OF THE KARNAFULI RIVER ESTUARY, CHATTOGRAM, BANGLADESH

Abstract

The activity concentrations of the natural radionuclides namely 238U, 232Th, 40K and 137Cs are measured for sediments samples collected from different locations of Karnafuli riverbed near estuary, Chattogram, Bangladesh. High-purity gamma spectrometry (HPGe detector) was used to determine the activity concentration of these radionuclides in 20 sediments samples were taken from Karnafuli River Estuary. The concentration of 238U varied in the range 23.75 ± 10.20 Bq/kg to 57.84 ± 13.80 Bq/kg with an average of 37.78 ± 9.77 Bq/kg, 232Th in the range 33.44 + 13.77 Bq/kg to 81.86 ± 14.71 Bq/kg with an average of 55.08 ± 13.40 Bq/kg and 40K in the range 400.41 ± 73.89 Bq/kg to 621.65 107.05 Bq/kg with an average of 439.31 ± 98.63 in sediments samples. The anthropogenic radionuclide 137Cs has not been detected in any samples. The results have been compared with those of different countries of the world and worldwide values. To assess the radiological hazard of the natural radioactivity, the absorbed dose rate, the radium equivalent activity (Raeq), the effective dose rate (Eeff), the annual effective dose equivalent (AEDE), the radioactivity level index (I), and the external (Hex) and internal (Hin) hazard indices were calculated. It can be concluded that no risk may threat the residents around Karnafuli River Estuary. Hence the probability of occurrence of any of the health effects of radiation is low. Hence, measurements have been taken as representing baseline values of these radionuclides in the sediments of studying area.