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 226 Ra, 232 Th and 40 K 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 226 Ra 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 226 Ra and 232 Th linked to a source enriched in radioactive minerals and 40 K related to a different sources high in K enriched minerals.