Measurements of Natural Radioactivity and Mössbauer Effect in Some Soil Samples Collected from the New Campus of Taif University, Saudi Arabia

Eleven soil samples from the new campus of Taif University and its neighboring areas, Saudi Arabia have been studied by high-resolution γ-ray spectroscopy, x-ray powder diffraction and Mössbauer spectroscopy to ascertain their overall characterization. The mean and range of the activity concentrations of 232 Th, 234 Th, 226 Ra, 40 K and 137 Cs isotopes in the soil samples are 1.68±0.2 (8.3 40.2), 9.83±0.1 (5.6 16.5), 12.97±0.2 (7 19.1), 625±10 (551 739) and 2.79±0.1 (0.7 3.9) Bq.kg -1 , respectively. The calculated radium equivalent of soil samples are lower than the limit set in the OECD report (370 Bq.kg −1 ). The major Mössbauer spectral components of soil samples are ferrous and ferric doublets. This result is consistent with X-ray powder diffraction results that show the presence of chlorite, biotite and vermiculite. Small amounts of hematite were also found in eight samples. The variation of the obtained Fe 2+ /Fe 3+ ratio is discussed in terms of the values of the radium equivalent activities to assess, if any, possible correlation between the specific activity of samples containing different contents of naturally occurring radioactivities and their Fe 2+ /Fe 3+ ratios.