Radiometric properties of virgin and cultivated soil around the Shazand Refinery Complex in Iran

Background: One of the main sources of exposure to radiation is terrestrial radionuclides in the environment. These radioisotopes are present in the Earthchr('39')s crust and can be increased by human activity such as mining of coal, oil, and minerals. Materials and Methods: In this study, 39 soil samples including virgin and cultivated were collected from around of the Shazand Refinery Complex(SRC) using a template and experimental method. The gamma spectrometry method was used to measure the specific activity of the 226Ra, 232Th, 40K and 137Cs radionuclides. Results: The average concentrations of 226Ra, 232Th, 40K and 137Cs in the cultivated (virgin) soil samples were 21.95 ± 0.27 (23.99 ± 0.37), 25.37 ± 0.29 (31.74 ± 0. 38), 416.72 ± 1.88 (461.09 ± 2.68) and 5.13 ± 0.08 (5.51 ± 0.14) in Bq kg-1. Excess lifetime cancer risk (ELCR) was obtained for cultivated (virgin) soil as 0.19 × 10-3 (0.22 × 10-3), which is close to the world average (0.29 × 10-3) and lowers than the maximum acceptable value (10-3). Conclusion:  The specific activities of natural radionuclides were in the global range and are lower than the maximum allowable value. The distribution map of 226Ra and 137Cs indicated some part of 226Ra, distributed as fly ash from a chimney, caused by the incineration of refinery waste. The radiological parameters calculated for both types of soil were lower than the maximum admissible values, and therefore there is no radiological hazard for people living in this area.