Studying the Concentration and Radiological Impact of Cesium-137 in Surface Soils of Al-Zawiya, Libya

Abstract

         High concentrations of radioactive elements are an indicator of the risk of radioactivity. The cesium radionuclide is one of the most important radionuclides. This study investigates the concentration and radiological impact of Cesium-137 (Cs-137) in surface soils within the Al-Zawiya region, Libya. A total of 19 soil samples were collected from various locations in September 2024, including areas near the Al-Zawiya oil refinery. Samples were prepared by drying, sieving, and sealing in Marinelli beakers for 30 days. Activity concentrations were determined using gamma-ray spectroscopy with an n-type HPGe coaxial detector system (GR6022). The specific activity of Cs-137 was calculated from the 661.66 keV photopeak, and corresponding absorbed dose rates and annual effective doses were derived using standard conversion factors.

        Cs-137 was detected in 9 samples (47.37%), with activity concentrations ranging from 0.1338 to 2.4037 Bq/kg and a mean of 0.6727 Bq/kg. The highest values were not associated with refinery infrastructure, indicating a fallout origin from historical nuclear events rather than local contamination. The resultant absorbed dose rates (0.0041 - 0.0721 nGy/h) and annual effective doses (0.0050 - 0.0109 µSv/year) are orders of magnitude below the public dose limit of 1 mSv/year and negligible compared to natural background radiation.