Sowole O
Keywords: Radionuclides, radionuclide concentration, dose rate, gamma spectrometry, radioactivity concentration
Abstract: Radioactivity concentrations and dose rates of 40K, 226Ra and 228Ra in fishes as internal dose rates from major rivers in Sagamu, Ogun State Southwest of Nigeria had been determined by gamma spectrometry using NaI (TI) detector coupled with a pre-amplifier base to a multiple channel analyzer (MCA). 15 samples of fishes were collected from three rivers: Majowopa, Ibu and Eruwuru. Tilapia zilli had the highest mean concentrations of 40K and 226Ra of values 89.13 ± 6.83Bq/kg and 3.06 ± 0.26Bq/kg respectively. The highest mean concentration of 228Ra was found in Papyrocranus afer with value 3.12 ± 0.29Bq/kg. The highest dose rates of 40K and 226Ra were obtained form Tilapia zilli with values of 0.00801mGy/yr and 5.36 x 10-7mGy/yr respectively. For 228Ra, Papyrocranus afer had the highest dose rate of value 3.50 x 10-13mGy/yr. The average dose rate of the radionuclides in the fishes was calculated to be 1.74 x 10-3mGy/yr which is below the 0.4 mGy/yr limit recommended by NCRP (1991) as reported by Blaylock et, al (1993) which has no negative radiological health implication to the aquatic animals.
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