Natural radioactivity and its radiological implications from soils and rocks in Jaintiapur area, North-east Bangladesh

Natural radioactivity concentrations in recent alluvial soils from swampy areas and Tertiary rocks from Jaintiapur were measured using gamma-ray spectrometer equipped with HPGe detector. The average radioactivity concentration of Ra-226, Th-232 and K-40 were 47 +/- 6, 64 +/- 5 and 762 +/- 40 Bqkg(-1) in soils, whereas, 25 +/- 2, 37 +/- 4 and 884 +/- 41 Bqkg(-1) in rock samples, respectively. Average radioactivity concentrations of studied soil and rock samples exceeded the world average except Ra-226 for rocks. Radio-elemental ratios suggest that an oxic depositional environment with low uranium and high thorium content. Regarding radiological hazard indices, radium equivalent activities (Ra-eq), external hazard index (H-ex) and internal hazard index (H-in) was found to be below the world permissible limits. Whereas, absorbed dose rate (D), and annual effective dose equivalent (AEDE) averages exceeded the world admissible values. Statistical studies show that radioactivity for Ra-226 and Th-232 linked to a source enriched in radioactive minerals and K-40 related to a different sources high in K enriched minerals.