Soil to Cassava Transfer Factors of Natural Radionuclides in Farms in Ini Local Government Area, Akwa Ibom State, Nigeria

Abstract

Knowledge of activity concentration of radionuclides in soil of our farmlands and the consequent transfer factors of the radionuclide to plants are necessary to estimate the contamination level of the soil, plants and food. The activity concentration of 40K, 238U and 232Th in soils and cassava in Ini Local Government Area, Akwa Ibom State, Nigeria were measured using gamma spectrometry. Activity concentrations of radionuclides in soils in the locations ranged from BDL (below detectable limit) to 298.76 ± 21.40 Bq/Kg for 40K; BDL to 7.95 ± 1.88 Bq/Kg for 238U and 2.59 ± 0.25 to 16.56 ± 1.61 Bq/Kg for 232Th. Activity concentration of the radionuclides in cassava in all locations ranged from 213.96 ± 15.38 Bq/kg to 520.58 ± 37.25 Bq//Kg for 40K; BDL to 33.02 ± 8.91  Bg/Kg for 238U and BDL to 16.34 ± 1.59 Bq/kg for 232Th. The activity concentrations of all the radionuclides were lower than the world standard.  Transfer factors obtained ranged between 3.21 to 4.18 for 40K; 0.93 to 12.64 for 238U and 0.75 to 1.01 for 232Th. Effective ingestion dose due to the consumption of cassava from the studied area obtained ranged between 1.31 to 1.74 mSv/yr and 3.52 to 4.69 mSv/yr for children and adult respectively. These values are above the 1.0 mSv/yr recommended dose limit for general public, therefore the consumption of this food stuff could pose a radiological health effect on humans. However the risk could be minimized when the cassava is cooked.