Impact of fertilizers on background radioactivity level in two newly developed desert areas

A survey of soils and plants was carried out to determine the environmental gamma background radiation levels in two newly developed desert areas. The materials and the standards were analyzed by gamma spectroscopy; a shielded high purity germanium detector was used to measure the natural concentration of 238U, 232Th and 40K activities in the samples. The radionuclide content in some commercial fertilizers was determined. The results of the analysis of specific activities in the fertilizers under study were 1.27–950.09 Bq/kg for 238U, 0.73–162.16 Bq/kg for 232Th and 10.22–23845.24 Bq/kg for 40K. All natural soil samples showed low-activity concen-trations. The concentrations of 238U (6.13–38.84 Bq/kg) and 232Th (2.58–25.69 Bq/kg) are quite similar, whereas that of 40K (113.91–9314.11 Bq/kg) are much higher for plant samples. Some of the results obtained are larger than the permissible international radioactivity levels. It is suitable in this regard to compare the activity values of the imported fertilizers and that fabricated in Egypt. The absorbed dose rate was found to be 1.91–1027 nGy/h and the radium equivalent activity concentration was 4.02–1840.98 Bq/kg for fertilizer samples. Soil and plant sample results were 11.86–415.29 nGy/h and 24.20–750.52 Bq/kg for the absorbed dose rate and the radium equivalent activity concentration, respectively. Banana plant contains the largest values. This article presents actual data from investigations of the soil–plant transfer of the primordial radionuclides for some fruits growing on these soils. The transfer factors of 0.35–1.821 for 238U, 0.227–0.480 for 232Th and 1.95–31.85 for 40K were obtained. The increase of the transfer of 40K reflects its great uptake to the fruits. Observed soil–plant factors vary widely, mainly as a result of different soil, vegetation types and environmental conditions. Taking into account the transfer factors of 137Cs to plants, the measured activity concentrations of this isotope should not endanger the health safety of the produced food.