Abstract
This work presents the first in-depth study of soil radioactivity in the mangrove forest of Bangladesh part of the Sundarbans. It used HPGe gamma-ray spectrometry to measure the amount of natural radioactivity in soil samples from Karamjal and Harbaria sites of the world’s largest mangrove forest. The activity concentrations of most of the
226
Ra (14±2 Bqkg
-1
to 35±4 Bqkg
-1
) and
232
Th (30±5 Bqkg
-1
to 50±9 Bqkg
-1
) lie within the world average values, but the
40
K concentration (370± 44 Bqkg
-1
to 660±72 Bqkg
-1
) was found to have exceeded the world average value. The evaluation of radiological hazard parameters revealed that the outdoor absorbed dose rate (maximum 73.25 nGyh
-1
) and outdoor annual effective dose (maximum 0.09 mSvy
-1
) for most samples exceeded the corresponding world average values. The elevated concentration of
40
K is mainly due to the salinity intrusion, usage of fertilizers and agricultural runoff, and migration of waste effluents along the riverbanks. Being the pioneering comprehensive research on the Bangladesh side of the Sundarbans, this study forms a baseline radioactivity for the Sundarbans before the commissioning of the Rooppur Nuclear Power Plant in Bangladesh.