Natural radioactivity in soils and medicinal plants of the Sundarban: Concomitant radiological risks and radionuclide transfer factor

The natural radioactivity ( 226 Ra, 232 Th, and 40 K) levels of some medicinal plants and soils in the Sundarban mangrove ecosystem in Bangladesh were assessed for the first time using gamma-ray spectrometry. Depth-wise activity concentration variations for most of the soil cores indicate an increase in radiological contamination in recent years. Although some radiological hazard parameters for soils are higher than the global average values, excess lifetime cancer risk values are below the acceptable limit. The activity concentrations of 226 Ra, 232 Th, and 40 K in the studied medicinal plant leaves varies from 9.03 ± 3.01 to 66.9 ± 8.2 Bq kg −1 , 25.3 ± 5.0 to 155 ± 16 Bq kg −1 , and 68.1…