DETERMINATION OF NATURAL RADIOACTIVITY LEVELS IN SURFACE SOILS OF OLD PHOSPHATE MINE AT RUSSAIFA OF JORDAN

Abstract

The aim of this study was to evaluate the concentration levels of naturally occurring radioactive materials (NORMs) of 238 U and 232 Th series and 40 K in surface soil samples of old phosphate mine at Russaifa of Jordan. The activity concentrations of NORMs in soil samples were determined by means of gamma-ray spectrometry system using a hyper-pure germanium (HPGe) detector in a low background configuration. The ranges of specific activity concentrations (SACs) of 238 U, 232 Th and 40 K were found to be 27.55 ± 7.55 to 420.19 ± 60.25, 222.35 ± 8.15 to 366.68 ± 92.47 and BDL to 2.40 ± 0.20 Bq kg −1 , with mean values of 207.10 ± 21.02, 265.95 ± 30.84 and 0.895 ± 0.105 Bq kg −1 , respectively in the surface soil samples collected from old phosphate mine. The average values of 587.49 ± 179.6 Bq kg-1 , 264.53 ± 78.6 nGy h-1 and 0.32 ± 0.09 mSv y-1 for radium equivalent activities, absorbed dose rates in air outdoors and annual effective dose equivalent, respectively, while the average values of 1.58 ± 0.48 and 2.14 ± 0.84 for external and internal radiation hazard indices, respectively were calculated for the analyzed samples to assess the radiological hazards arising from natural radioactivity in surface soils. These obtained values in old phosphate mine were found to be higher than the internationally acceptable limits reported by UNSCEAR ̶ 1988, UNSCEAR ̶ 2000 and ICRP ̶ 1990.