Geospatial distribution of natural radionuclides and radiological assessments in Asia's largest coastal lagoon sediment, Chilika, India

The pioneer work on the measurement and distribution of natural radioactivity levels was carried out in the sediment samples of Asia's largest coastal lagoon, Chilika, India. The activity concentrations of radionuclides in the sediment samples measured by using a high-resolution HPGe semiconductor detector gamma-ray spectroscopy system, and the average activity concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 28.25 ± 7.85, 84.27 ± 30.93 and 610.57 ± 89.74 Bq kg^-1. The contour map, drawn using the Kriging method, illustrates the geospatial distribution of each radionuclide in Chilika. The results show the distribution of radionuclides and are compared with similar results from different locations in the worldwide. The activity concentrations are also compared with the average values of the world and India. The radiological indices for the lagoonal system were calculated, and the mean values are 195.77 Bq kg^-1 for radium equivalent (Ra_eq), 167.53 nGy h^-1 for absorbed gamma dose rate (D_R), 0.21 mSv y^-1 for annual effective dose equivalent (AEDE), 631.27 µSv y^-1 for Annual gonadal dose equivalent (AGDE), 0.53 for external hazard index (H_ex), 0.61 for internal hazard index (H_in), 0.72 for gamma representative level index (Iγr), and 0.14 for alpha index (Iα). The mean value of the Ra_eq obtained from the study area was less than the international value of 370 Bq kg^-1. All the radiological assessment indices indicated that the observed values are below the threshold values.