Assessment of Natural Radioactivity and Radiological Health Hazards in Core Sediments of the Sundarbans Using Gamma-Ray Spectrometry

Abstract

In this study, the activity concentrations of naturally occurring radionuclides (Ra-226, Th-232 and K-40) in core sediment samples from three different locations of the Sundarbans mangrove forest, Bangladesh were determined using gamma-ray spectrometry technique. The activity concentrations of the artificial radionuclides Cs-137 in the studied sediment samples are below the detection limit (<9.1 Bq/kg). The quality control of the analysis was studied by analyzing certified reference standard IAEA-Soil-6. The activity concentrations (Bq/kg) of the naturally occurring radionuclides 226Ra, 232Th and 40K in sediment samples of the Sundarbans were found as 22.8±2.5 to 153.3±13.3, 50.8±2.2 to 128.5±8.7 and 868±50 to 17059±251, respectively. For the three cores, the mean activity concentrations of the natural radionuclides are of the order of K-40>Th-232>Ra-226. From this study, it is observed that activity concentrations of 232Th and 40K in sediments are relatively higher than those of the world average values. The depth-wise variations of the activity concentrations show that there is an increasing trend in activity concentrations in the surface sediments than the deeper layers. Different radiological hazard indices calculated in this study indicate that the sediments at some cores indicate some extent radiological risks to the biota of the Sundarbans. Finally, since there is no literature data available on activity concentration of the naturally occurring radionuclides in the Sundarbans, the results of this study will be used as baseline data for future study and also to assess radiological hazards in the sensitive Sundarbans mangrove forest.