Distribution of natural and anthropogenic radionuclides and associated radiation indices in the Southwestern coastline of Caspian Sea

Abstract

The distribution pattern of natural radionuclides (226Ra, 232Th, and 40K) and anthropogenic radionuclide (137Cs) in surface sediment samples from the southwestern coastline of the Caspian Sea were determined to estimate the radiation hazard indices using a high-purity germanium HPGe gamma-ray detector. The activity concentrations of the sediment samples ranged from 22.5 ± 1.0 to 47.4 ± 2.2 Bq kg−1 dry weight (dw) for 226Ra, 6.5 ± 0.1 to 18.7 ± 0.7 Bq kg−1 dw for 232Th, 559.9 ± 30.9 to 233.2 ± 19.4 Bq kg−1 dw for 40K, and 0.9 MDL (minimum detection limit) to 2.7 ± 0.1 Bq kg−1 dw for 137Cs. Based on the measured values, radiological risk indices were estimated. The mean values for absorbed dose rate, ambient dose equivalent rate, and excess lifetime cancer risk, were calculated as 35.7 nGy h−1, 47.9 nSv h−1, and 0.2, respectively.