Geogenic Radiological Dose and Activity Concentrations in Phosphate Rocks and Industrial Tailings from Kaduna, Northwestern Nigeria

Abstract

This study assesses the activity concentrations of Naturally Occurring Radioactive Materials (NORMs) in phosphate rocks, tailings, and related materials from a superphosphate fertilizer industry in Kaduna, Nigeria. Samples of sludge, soil, sediment, phosphate rock, and phosphogypsum were analyzed using Instrumental Neutron Activation Analysis (INAA) with high-purity germanium detectors. Radiological parameters, including Annual Effective Dose Equivalent (AEDE), External and Internal Hazard Indices, Annual Gonadal Dose Equivalent (AGDE), Radium Equivalent Activity (Raeq), Absorbed Gamma Dose Rate (D), Activity Utilization Index (AUI), and Gamma Index (Iγ) were computed following UNSCEAR (2000) formulations. The mean AEDE, AGDE, and Raeq values were 87.0 µSv/y, 517.7 µSv/y, and 137.3 Bq/g, respectively. Most samples exceeded global averages, indicating potential radiological risks to the surrounding environment. These findings highlight the need for continuous monitoring and improved waste management practices in the fertilizer industry