Evaluating Radioactivity Levels and Determining Risk Indicators in Plant Samples in Kirkuk- Iraq

Abstract

This study aims to assess the natural radioactivity of radioactive isotopes (Ra²²⁶, Th²³²and K⁴⁰) in plant samples using a high-purity germanium (HpGe) gamma-ray spectrometer. Fifteen plant samples, equally distributed among vegetables, legumes, and grains, were collected from local markets in Kirkuk, Iraq. The radioactivity of radionuclides was analyzed, and relevant radiation risk indicators were calculated. Results showed that the specific activity of Ra²²⁶ ranged from (0.46 to 50.04 Bq.kg^-1) while the specific activity of Th²³² ranged from below detection limits (B.D.L. to 25.42 Bq.kg^-1). For K⁴⁰, the specific activity ranged from (90.35 to 587.60 Bq.kg^-1). Radiation risk indicators were calculated, with radium equivalent (Ra_eq) values ranging from (7.946 to 118.772 Bq.kg^-1). The gamma level index (I_γ) ranged from (0.067 to 0.876), while the external hazard coefficient (H_ex) ranged from (0.021 to 0.320), and the internal hazard coefficient (H_in) ranged from (0.022 to 0.456). The absorbed dose rate in air (D) was estimated to range from (4.268 to 63.728 nGy.h^-1). Annual external and internal effective doses were calculated, with maximum values of (0.078 and 0.312 mSv.y^-1), respectively, and minimum values of (0.001 and 0.020 mSv.y^-1), respectively. Variation in radiation risk indicator values was observed, with some within internationally permissible limits, while others exceeded these limits, particularly in vegetable samples. This variation is attributed to the potential use of irrigation water with high radioactive content, which may pose a potential risk to living organisms that depend on these plants for food.