Assessing geochemical and natural radioactivity impacts of Hamadat phosphatic mine through radiological indices.

The utilization of phosphorite deposits as an industrial resource is of paramount importance, and its sustainability largely depends on ensuring safe and responsible practices. This study aims to evaluate the suitability of phosphorite deposits for industrial applications such as the production of phosphoric acid and phosphatic fertilizers. To achieve this goal, the study meticulously examines the geochemical characteristics of the deposits, investigates the distribution of natural Radioactivity within them, and assesses the potential radiological risk associated with their use. The phosphorites are massive and collected from different beds within the Duwi Formation at the Hamadat mining area. They are grain-supported and composed of phosphatic pellets, bioclasts (bones), non-phosphatic minerals, and cement. Geochemically, phosphorites contain high concentrations of P2O5 (23.59-28.36 wt.%) and CaO (40.85-44.35 wt.%), with low amounts of Al2O3 (0.23-0.51 wt.%), TiO2 (0.01-0.03 wt.%), Fe2O3 (1.14-2.28 wt.%), Na2O (0.37-1.19 wt.%), K2O (0.03-0.12 wt.%), and MnO (0.08-0.18 wt.%), suggesting the low contribution of the detrital material during their deposition. Moreover, they belong to contain enhanced U concentration (55-128 ppm). They are also enriched with Sr, Ba, Cr, V, and Zn and depleted in Th, Zr, and Rb, which strongly supports the low detrital input during the formation of the Hamadat phosphorites. The high Radioactivity of the studied phosphorites is probably due to the widespread occurrence of phosphatic components (e.g., apatite) that accommodate U in high concentrations. Gamma spectrometry based on NaI (Tl) crystal 3×3 has been used to measure occurring radionuclides in the phosphorite samples. The results indicate that the radioactive concentrations' average values of 226Ra, 232Th, and 40K are 184.18±9.19, 125.82±6.29, and 63.82±3.19 Bq Kg-1, respectively. Additionally, evaluations have been made of the radiological hazards. The calculated risk indicators exceeded the recommended national and world averages. The data obtained will serve as a reference for follow-up studies to evaluate the effectiveness of the Radioactivity of phosphatic materials collected from the Hamdat mine area.

Maastrichtian Anoxia and Its Influence on Organic Matter and Trace Metal Patterns in the Southern Tethys Realm of Egypt during Greenhouse Variability.

Maastrichtian organic-rich sediments of Egypt were deposited under a warm greenhouse climate along the stable African shelf. This study presents an integrated analysis of the geochemical, mineralogical, and palynological data from Maastrichtian organic-rich sediments in the northwest Red Sea region of Egypt. The aim of the study is to assess the impact of anoxia on the enrichment of organic matter and trace metals and to reconstruct a model for the formation of these sediments. The sediments are hosted within the Duwi and Dakhla formations, covering an interval of ∼1.14-2.39 million years. Our data indicate variable bottom-water oxygen-level conditions for early and late Maastrichtian sediments. The C-S-Fe systematics and redox geochemical proxies (e.g., V/(V + Ni), Ni/Co, and Uauthigenic) suggest dysoxic to anoxic depositional conditions for the late and early Maastrichtian organic-rich sediments, respectively. The early Maastrichtian sediments contain abundant small-sized framboids (average = 4.2-5.5 µm), suggesting anoxic conditions, while the late Maastrichtian sediments have larger framboids (average = 4-7.1 µm), indicating dysoxic conditions. The palynofacies analyses reveal the high abundance of amorphous organic matter and confirm the predominance of anoxic conditions during deposition of these organic-rich sediments. The early Maastrichtian organic-rich sediments have a significant Climate concentration of Mo, V, and U, indicating high biogenic production rates and distinct preservation conditions. Additionally, the data imply that oxygen deficiency conditions and low sedimentation rates were the main factors controlling the preservation of organic matter in the studied sediments. Overall, our study provides insights into the environmental conditions and processes that led to the formation of the Maastrichtian organic-rich sediments in Egypt.