Mineralogical and Radiological Investigation of rock samples from Geddami Mountain, Eastern Desert, Egypt.

Abstract

An investigation on terrestrial natural radiation in relation to mineral composition in soil and rocks have received considerable importance in the last years to establish a baseline data for future radiation impact assessment, radiation protection and exploration. The present study focused on the evaluation of naturally occurring radionuclides 226Ra, 232Th and 40K and the associated hazard indices in twenty-three rock samples from Geddami Mountain, Egypt. The measurements are carried out by gamma-ray spectroscopy technique using HPGe detector with special designed shield. Also, the radon exhalation rate and effective radium content are estimated in some samples by the sealed can technique using the CR-39 detector. Furthermore, the X-ray fluorescence technique was used for determining the strategic elements that may be present in the selected samples. The mean activity concentrations of 226Ra, 232Th and 40K were found to be 100.85±1.81, 59.94±1.12 and 1067.93±8.07 Bq kg-1 respectively. These values exceed the maximum international limits. The mean values of radium equivalent, external hazard index, internal hazard index and radiation level index are estimated and found to be 268.79, 0.73, 1.00 and 0.99Bq kg-1respectively. The mean values of the absorbed dose rate, annual effective dose equivalent, annual gonadal dose equivalent and the excess lifetime cancer risk are calculated and found to be 127.33nGy h-1, 0.16mSv y-1, 0.90mSv y-1 and 0.54 × 10-3 receptively. Also, the mean values of radon exhalation rate (areal and mass) were found to be 2.95±0.39Bq m-2 h-1 and 0.08±0.01Bq kg-1 h-1 respectively. The mean values of the effective radium content and the emanation powerwere found to be 10.91±1.44Bq kg-1 and 0.11±0.856 respectively. Furthermore, The X-ray analysis showed that there are considerable concentrations of some strategic elements such as Fe, Al, Zr and Ti have beenobserved.