Abstract:
ABSTRACT
The objective of this study is to determine the background data for the levels of
gamma radiation in soil, groundwater sources and food in the communities
along the Tano Basin, an oil field in Ghana. The mean activity concentrations
measured for 238U, 232Th and 40K in soil samples are 8.65 Bq/kg, 12.51 Bq/kg
and 214.11 Bq/kg respectively. The activity concentrations of 226Ra, 228Ra, and
40K in the water obtained were in the range of 0.14±0.01 to 1.38±0.22 Bq/L,
0.18±0.01 to 1.41±0.18 Bq/L and 0.46±0.02 to 5.92±0.10 Bq/L respectively.
The total annual effective dose to the public was estimated to be 35.34 μSv per
year. Absorbed dose rate, annual effective dose, hazard indices (Hex and Hin)
were calculated. The absorbed dose rates and annual effective dose were
determined and found to be in the range of 7.79 to 37.79 nGyh-1 and 9.56 x100
to 4.64 x101 μSvy-1 respectively. The total annual effective dose were lower
than allowable limit set by International Commission on Radiological
Protection (ICRP) 1mSvy-1. Hazard indices (Hex and Hin) were 0.04 to 0.22 and
0.05 to 0.25 respectively whilst excess lifetime cancer risk (ELCR) were
calculated to be in the range 3.35 x 10-5 to 1.62 x10-4 and found to be within
internationally recommended values. The concentration of metals in soil were
in the order Fe > Zn > Cd > Mn > Pb > Ni. The estimated carcinogenic risk to
the public from exposure to the metals in soil varies from 3.9 x10-9 for Ni to
1.04 x10-6 for Cd. The average activity concentrations are 0.70, 52 and 25.63
Bq/kq respectively for 238U, 232Th and 40K in cassava samples. The estimated
transfer factors for 238U, 232Th, and 40K are in the range 0.017 – 0.553, 0.003 –
0.078 and 0.019 – 0.057 respectively. The mean transfer factors (TF) are 0.271
(238U), 0.028 (232Th) and 0.033 (40K).
