Comparison of Radiation Levels in the Soil and Rocks in the Areas Surrounding Old Phosphate Mine, Russaifa, Jordan

Abstract The activity concentrations of the terrestrial naturally occurring radionuclides 214 Pb, 214 Bi (from 238 U series), and 228 Ac (from 232 Th series) and 40 K were measured in soil and rock samples obtained from three sites of the Russaifa mine and its surrounding in the Russaifa region using an HPGe-detector of 20 % relative efficiency. While the soil activity (in Bq/kg) was found to be: 408.63 ± 26, 383.9 ± 4.7, and 383.0 ± 4.0 for 238 U, 214 Bi, and 214 Pb, respectively. The rock activity was found to be 225.4 ± 19, 180.36 ± 3.9, and 179.47 ± 3.1 for 238 U, 214 Bi, and 214 Pb, respectively. Our results reveal that the average activity concentrations in the mine (site 1) are higher than worldwide average values [6] for 238 U, 214 Pb, and 214 Bi. In contrast, the results show that the average absorbed dose rates in the other sites 2 and site 3 are lower than the world average for all radionuclides measured in this study. Also, the average activity concentrations in soil samples 238 U, 214 Pb, and 214 Bi are higher than the average activity concentrations in rock samples in all sites. Furthermore, the average absorbed dose rate (in nGy h-1) was found to be 265.3 for 238 U, 233.3 for 214 Bi, and 13.3 for 214 Pb, respectively, and the average absorbed dose rates for both 228 Ac and 40 K were below the minimum detectable activity (MDA). Moreover, the average annual effective dose rates in soil and rock samples were estimated. While it is found to be 366.90 µSv for 238 U, 306.84 µSv for 214 Bi, and 37.58 µSv for lead in soil samples, for the rock samples it is found to be 163.75 µSv for 238 U, 105.83 µSv for 214 Bi, 13.05 µSv for lead. However, the average annual effective dose rates for 214 Bi and 40 K in soil and rock samples are below the minimum detectable activity (MDA). The results display that the average outdoor annual effective doses for both 238 U and 214 Bi are higher than the world average and the average outdoor annual effective dose equivalents for the other radionuclides are lower than the world average. They also show that the average outdoor annual effective doses in soil samples for 238 U, 214 Pb, and 214 Bi are higher than the average outdoor annual effective doses in rock samples.