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

ASSESSMENT OF ANNUAL EFFECTIVE DOSE DUE TO INHALATION AND INGESTION OF RADON FROM GROUNDWATER AT THE SOUTHEAST COASTAL AREA, BANGLADESH.

Naturally occurring radon-222 was evaluated for its use in estimating annual effective dose exposure in groundwater samples of the southeast coastal area of Bangladesh. On-site radon concentration was measured in groundwater using AlphaGUARD PQ2000 PRO (Saphymo, Germany) radon monitor. The measured values range 0.36-15.70 Bq per l, which lies within the safe limit of 4-40 Bq per l recommended by UNSCEAR. On the contrary, few samples show radon concentration above the safe limit of 11.1 Bq per l recommended by USEPA. The mean annual effective doses due to ingestion and inhalation resulting from radon in groundwater vary from 0.99 to 42.87 µSv per y with an average value of 12.45 µSv per y, which is far below the safe limit 100 µSv per y recommended by WHO and EU. Results reveal that there is no significant public health hazard due to radon ingestion and inhalation from groundwater in the study area.

RADON CONCENTRATION IN SOIL AND GROUNDWATER OF WEST COASTAL AREA, BANGLADESH.

On-site radon concentration has been measured in soil gas and ground water using AlphaGUARD PQ2000 PRO (Saphymo, Germany) radon monitor at the west coastal area of Bangladesh. The measured radon concentration in ground water samples is in the range of 1.41 ± 0.29 to 3.2 ± 0.59 Bq/l with the mean value of 2.33 ± 0.50 Bq/l, which lies within the safe limit recommended by UNSCEAR (2008). The total annual effective dose estimated due to radon concentration in ground water ranges from 3.85 to 8.74 µSv/y with the mean value of 6.37 µSv/y, which is lower than the safe limit set by WHO (2004) and EU (1998). In soil samples, radon concentration has been measured at three different depths (0, 20 and 40 cm) in each location. The highest and the lowest concentrations are 4790 ± 51 and 10 ± 04 Bq/m3 at 40 and 0 cm (surface) depth, respectively, which lie within the natural background levels.