Natural radioactivity investigations in soil samples obtained from phosphate hills in the Russaifa region, Jordan

The specific activity, hazard index, and the annual effective dose of the terrestrial naturally occurring radionuclides (238U, 232Th, and 40K) were determined in soil samples obtained from 20 sites of phosphate hills in the Russaifa region using an HPGe-detector of 50% relative efficiency. The resolution is 2 keV for the 1.33 MeV 60Co. The soil activity ranged from 5.3 to 1201.1 Bq kg−1 for 238U, 2.2 to 31.2 Bq kg−1 for 232Th, and 19.4 to 288.4 Bq kg−1 for 40K. Annual effective dose was found in the range 0.03–0.69 mSv. The external hazard index ranged from 0.15 to 3.29 Bq kg−1, while the global value given in UNSCEAR, 2000 publications is 1 Bq kg−1. The average values of the radium equivalent activities were determined for all sites and they were found to be approximately 319 Bq kg−1. This value is below the limit of 370 Bq kg−1 recommended by . The average value of the radium equivalent activities for certain locations (sample numbers: 2, 3, 4, 9, 10, and 14) is above the same limit.

► External annual effective dose was evaluated in phosphate hills in the Russaifa region, Jordan.
► External hazard index parameter exceeds the limit recommended by OECD (1979).
► Results are an important alert to avoid the use of this soil in the construction of dwellings.
► Data obtained will serve as a baseline for assessing the radiation exposure.