Radiological assessment of natural radionuclides in soil within and around crude oil flow and gas compression stations in the Niger Delta, Nigeria

Abstract

Natural radionuclide concentrations in soil samples collected within and around crude oil flow and gas compression stations in the Niger Delta, Nigeria, were determined using gamma-ray spectroscopy. The mean activity concentrations of 40K, 238U and 232Th varied from 30.1 ± 3.0 to 59.0 ± 17.1, BDL to 8.8 ± 2.3 and 7.9 ± 3.7 to 10.9 ± 1.9 Bq.kg-1, respectively. The 40K, 238U and 232Th contents of the soil samples are very low compared with the world average for natural background area. The absorbed dose rate and effective dose ranged from 6.9 to 11.1 nGy.h-1 and 8.5 to 13.6 μSv.y-1, respectively. The annual gonadal dose equivalent rate ranged from 48.9 to 77.5 μSv.y-1, which is lower than the world average of 0.30 mSv.y-1. The radium equivalent activity and the external hazard index of the soil samples were below the recommended limits of 370 Bq.kg-1 and unity, respectively. The results obtained reveal that there is no significant radiation hazard due to natural radionuclides of the soil samples in the studied areas. © EDP Sciences, 2010.