Assessment of natural and anthropogenic radioactivity levels and their radiological hazards in surface soil samples around oil refinery, Little Aden City, Yemen

The activity concentration of global fallout of 137Cs and naturally- occurring radioactive materials (NORM), which primarily due to the geological and geographical condition of soil. and maybe occur from oil and gas burring processes and consequently accumulate on surface soil around the oil refinery in Aden Assoghra city, Yemen were studied by use the gamma-ray spectrometer equipped with a high purity germanium (HPGe) detector and specially designed shield. The average concentrations of 226Ra, 232Th, and 40K expressed in (Bq kg−1) of the studied samples were (13 ± 0.44) Bq kg−1, (22.1 ± 0.64) Bq kg−1 and (509 ± 9) Bq kg−1, respectively. Low concentrations of 137Cs were noted from some sample in the study area, where ranged from (0.3 ± 0.2) to (1.7 ± 0.2) Bq kg-1. The average values of calculated radiological hazard indices were 40.6 nGy h−1 (absorbed dose rate outdoors), 0.05 mSv y−1 (annual effective dose outdoors), 0.279 mSv y−1 (annual effective dose indoors), 83.7 Bq kg−1 (radium equivalent), 0.23 (external hazard index), 0.26 (internal hazard index), 0.65 (representative level index), 0.174×10-3 (the excess lifetime cancer risk ELCR) and 0.292mSv y−1 (annual gonadal equivalent dose, AGED).