| Abstract | The radioactivity levels are poorly studied in non-coastal arid regions. For this reason, 38 locations covering an area of about 350 km2 in northeast Sinai, Egypt, were investigated by ? -ray spectroscopy. Moderately significant correlations among 238U, 234Th, and 226Ra isotopes and low significant correlations between the concentrations of 238U-series and 232Th in sand were obtained. No evidence of correlation was found between the concentrations of radioisotopes and pH, grain size, total organic matter content, bicarbonate or calcium carbonate concentrations of the sand samples. The mean values of soil-to-plant transfer factor were 0.15, 0.18, 1.52 and 0.74 for 226Ra, 232Th, 40K, and 137Cs, respectively. The range of concentrations of 226Ra,232Th, and 40K in water samples collected from five wells were |