Evaluation of radionuclide concentrations and external gamma radiation levels in phosphate ores and fertilizers commonly used in Algeria

In this paper, radionuclide concentrations of Ra-226, Th-232 and K-40 contained in two phosphate ores and six granular fertilizer samples were determined using gamma-ray spectrometry. The mean activity concentrations of Ra-226, Th-232 and K-40 were found to be 255 +/- 12, 193 +/- 7 and 23 +/- 6 Bq kg(-1), respectively, in phosphate ores and 86 +/- 4, 12 +/- 2 and 1348 +/- 95 Bq kg(-1), respectively, in phosphate fertilizers. The total absorbed dose rates in air (D) calculated from the concentrations of the three radionuclides ranged from 14 to 297 nGy year(-1), and the external annual effective dose rates (AEDR) were determined to be between 0.01 and 0.36 mSv year(-1). Based on the annual effective dose calculations, the estimated excess lifetime cancer risks due to phosphate ores and phosphate fertilizers are 1.02 x 10(-3) and 0.42 x 10(-3), respectively. The mean values of radium equivalent activity (Ra-eq), external hazard index (H (ex)), and internal hazard index (H (in)) were also calculated, and their mean values are 532 Bq kg(-1), 1.9 and 2.25 respectively, in phosphate ores and 205 Bq kg(-1), 0.55 and 0.78, respectively, in fertilizers. Results were discussed and compared with those reported in similar studies and with internationally recommended values.