Radiological Risk Parameters of the Phosphorite Deposits, Gebel Qulu El Sabaya: Natural Radioactivity and Geochemical Characteristics

Abstract

This study investigates the distribution of natural radioactivity and geological, geochemical, and environmental risk assessments of phosphorite deposits to determine their suitability for international applications (such as phosphoric acid and phosphatic fertilizers). The examined Late Cretaceous phosphorite deposits belong to the Duwi Formation, which is well exposed on the southern scarp boundary at the central part of Abu Tartur Plateau, Gebel Qulu El Sabaya, East Dakhla Oasis. This formation is classified into lower phosphorite, middle shale, and upper phosphorite members. The lower phosphorite ranges in thickness from 2 to 3.5 m and mainly comprises apatite (possibly francolite), dolomite, calcite, quartz, hematite, anhydrite, and kaolinite. They contain an average concentration of CaO (38.35 wt.%), P2O5 (24.92 wt.%), SiO2 (7.19 wt.%), Fe2O3 (4.18 wt.%), MgO (3.99 wt.%), F (1.59 wt.%), Al2O3 (1.84 wt.%), Na2O (1.33 wt.%), and K2O (0.22 wt.%). Natural radioactivity and radiological parameters were investigated for fifteen samples of phosphorites using a NaI (Tl) scintillation detector. Absorbed dose rates, outdoor and indoor annual effective dose, radium equivalent activity, external and internal hazard, and excess cancer risk values are higher than the recommended levels, reflecting that exposure to these deposits for a long time may lead to health risks to human organs. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.