Activity concentration of natural radionuclides and transfer factors from soil to vegetable in parts of South South Nigeria

Abstract

Naturally occurring radionuclide materials are known to exist in soils and is transferred into vegetables and eventually gets into food chain. This work was aimed at determining the activity concentration of these radionuclides in soils and vegetable (fluted pumpkin) and the internal exposure due to the consumption of these materials in the vegetable in parts of South South Nigeria particularly Etim Ekpo Local Government area. The activity concentrations of twenty (20) soil samples and 20 vegetable samples from the farmlands were determined using gamma spectrometry. The activity concentration for 40K ,232Th and 238U from the soil samples ranged from 6.69±0.35 (Bqkg-1) to 168.19 ±8.82 (Bqkg-1) ,0.23 ±0.01 (Bqkg-1) to 5.91 ±0.35 (Bqkg-1) and BDL to 21.53±2.5 (Bqkg-1) respectively. The activity concentration of 40K, 232Th and 238U in the vegetable ranged from (584.23±27.71) Bqkg-1 to (958.67±48.46) Bqkg-1, from (1.84±0.11) Bqkg-1 to (9.72 ±0.56) and from (BDL) to (38.34±3.74) Bqkg-1 respectively. Transfer factors obtained ranged between 12.07±4.7 to 35.35 ±27.9 for 40K, 1.80±0.125 to 5.76 ± 4.31 for 232Th and BDL to 21.05 for 238U. Effective ingestion dose due to the consumption of vegetable from the study area obtained as 0.0021mSvy-1. This value is less than the 0.29mSvy-1 recommended dose limit for the general public; therefore, the consumption of this vegetable could not cause a radiological health effect on its consumers. However negligible or low risk could be minimised when the vegetable is washed and cooked before being consumed. Hence, the results obtained in this study indicate that the activity concentration of the farmland soils and crops represent no significant health risk on the farmers and the consumers of the vegetables.