Ahmed Abdefattah Elnazer

The greisens discussed in the present study are associated with the Homrit Akarem post-collisional granites, which are exposed near the western edge of the Egyptian Nubian Shield in the Southeastern Desert of Egypt. The Homrit Akarem granites intruded into Neoproterozoic country rocks, with sharp intrusive contacts. The marginal parts of the Homrit Akarem intrusion underwent extensive post-magmatic metasomatism, resulting in the formation of albitized granite and greisens. The Homrit Akarem greisens occur as veins and stockworks, which can be classified into four types: muscovite-rich, cassiterite-rich, topaz-rich, and beryl-rich greisens. Based on petrographic inspection, we identified ore minerals (cassiterite, beryl, topaz, muscovite, Nb-Ta oxides, tourmaline, fluorite, and corundum) in the greisens using electron probe microanalysis. The Homrit Akarem mineralized greisens were formed in a magmatic cupola above A-type magma, where fluid–rock interactions played a significant role in their formation. The accumulation of residual volatile-rich melt and exsolved fluids in the apical part of the magma chamber produced albitized granite, greisens, and quartz veins that intruded into the peripheries of the granitic intrusion and its surrounding country rocks. The variation in the mineralogy of the studied greisens indicates the diverse chemical composition of both the hydrothermal/magmatic fluids and the host granites. The simultaneous decrease in temperature and pressure is considered a crucial factor that controlled mineralization in the apical parts of the magma chamber. The occurrence of cassiterite, beryl, topaz, tourmaline, muscovite, and Nb-Ta oxides in the studied greisens suggests a potential polymetallic deposit of industrial minerals.

The current work records for the first time the rare-metal pegmatites with mixed NYF-LCT located at Wadi Sikait, south Eastern Desert of the Egyptian Nubian Shield. Most of the Sikait pegmatites are associated with sheared granite and are surrounded by an alteration zone cross-cutting through greisen bodies. Sikait pegmatites show zoned and complex types, where the outer wall zones are highly mineralized (Nb, Ta, Y, Th, Hf, REE, U) than the barren cores. They consist essentially of K-feldspar, quartz, micas (muscovite, lepidolite, and zinnwaldite), and less albite. They contain a wide range of accessory minerals, including garnet, columbite, fergusonite-(Y), cassiterite, allanite, monazite, bastnaesite (Y, Ce, Nd), thorite, zircon, beryl, topaz, apatite, and Fe-Ti oxides. In the present work, the discovery of Li-bearing minerals for the first time in the Wadi Sikait pegmatite is highly significant. Sikait pegmatites are highly mineralized and yield higher maximum concentrations of several metals than the associated sheared granite. They are strongly enriched in Li (900–1791 ppm), Nb (1181–1771 ppm), Ta (138–191 ppm), Y (626–998 ppm), Hf (201–303 ppm), Th (413–685 ppm), Zr (2592–4429 ppm), U (224–699 ppm), and ∑REE (830–1711 ppm). The pegmatites and associated sheared granite represent highly differentiated peraluminous rocks that are typical of post-collisional rare-metal bearing granites. They show parallel chondrite-normalized REE patterns, enriched in HREE relative to LREE [(La/Lu)_n = 0.04–0.12] and strongly negative Eu anomalies [(Eu/Eu*) = 0.03–0.10]. The REE patterns show an M-type tetrad effect, usually observed in granites that are strongly differentiated and ascribed to hydrothermal fluid exchange. The pegmatite has mineralogical and geochemical characteristics of the mixed NYF-LCT family and shows non-CHARAC behavior due to a hydrothermal effect. Late-stage metasomatism processes caused redistribution, concentrated on the primary rare metals, and drove the development of greisen and quartz veins along the fracture systems. The genetic relationship between the Sikait pegmatite and the surrounding sheared granite was demonstrated by the similarities in their geochemical properties. The source magmas were mostly derived from the juvenile continental crust of the Nubian Shield through partial melting and subsequently subjected to a high fractional crystallization degree. During the late hydrothermal stage, the exsolution of F-rich fluids transported some elements and locally increased their concentrations to the economic grades. The investigated pegmatite and sheared granite should be considered as a potential resource to warrant exploration for REEs and other rare metals.

This research provides a comprehensive examination of flood risk mitigation in Saudi Arabia, with a focus on Wadi Al-Laith. It highlights the critical importance of addressing flood risks in arid regions, given their profound impact on communities, infrastructure, and the economy. Analysis of morphometric parameters ((drainage density (Dd), stream frequency (Fs), drainage intensity (Di), and infiltration number (If)) reveals a complex hydrological landscape, indicating elevated flood risk. due to low drainage density, low stream frequency, high bifurcation ratio, and low infiltration number. Effective mitigation strategies are imperative to protect both communities and infrastructure in Wadi Al-Laith. Geophysical investigations, using specialized software, improve the quality of the dataset by addressing irregularities in field data. A multi-layer geoelectric model, derived from vertical electrical sounding (VES) and time domain electromagnetic (TDEM) surveys, provides precise information about the geoelectric strata parameters such as electrical resistivity, layer thicknesses, and depths in the study area. This identifies a well-saturated sedimentary layer and a cracked rocky layer containing water content. The second region, proposed for a new dam, scores significantly higher at 56% in suitability compared to the first region’s 44%. The study advocates for the construction of a supporting dam in the second region with a height between 230 and 280 m and 800 m in length. This new dam can play a crucial role in mitigating flash flood risks, considering various design parameters. This research contributes to flood risk management in Saudi Arabia by offering innovative dam site selection approaches. It provides insights for policymakers, researchers, and practitioners involved in flood risk reduction, water resource management, and sustainable development in arid regions globally.

The efficient removal of heavy metals from water is a critical environmental problem. Photocatalysis is a new and rapidly growing field of research that offers a promising approach. In this study, ilmenite ore (IL) samples procured from the Abu Ghalaga area in Egypt were functionalized through a facile process using hydrogen peroxide. Different characteristic techniques were utilized to examine both the physical and chemical properties of all ilmenite samples including XRF, XRD, SEM, EDX, FTIR, and BET. The XRF data of collected ores (IL samples) was demonstrated as the major oxides TiO2 (36.61-39.73 wt%) and Fe2O3 (55.04-55.15 wt%). According to XRD, The main mineral in the Abu Ghalaga ilmenite ore samples is ilmenite Fe(TiO3) ranging from (78% -83%) While the hematite mineral (Fe2O3) ranging from (17% - 22%). The photocatalytic efficiencies of the functionalized ilmenite samples (f-IL) were investigated for the removal of Pb(II) ions under visible light irradiation in an aqueous solution. All the functionalized ilmenite samples (f-IL) samples exhibited higher specific surface area and total pore volume than their source ilmenite ores (IL). The f-IL samples displayed effective photocatalytic removal of Pb(II) ions compared to the unfunctionalized ones under optimum conditions. The maximum adsorption capacity (qm) recorded was 309.7 mg/g for the 1-f-IL sample with removal efficiency reaching 97.6% at pH 7, temperature 25 oC, and catalyst dosage 20 mg after 60 min irradiation time under visible light. This study highlights the superior photocatalytic efficiency of functionalized ilmenite towards the removal of Pb(II) ions in an aqueous solution under visible irradiation.

Siwa Oasis is of great historical, environmental, and scientific importance, as it contains unique archeological and geological features. Groundwater is the main source of freshwater in that oasis. The carbonate aquifer groundwater, used for irrigation, was sampled to evaluate factors controlling quality changes spatially and temporally by applying hydrochemical and statistical analyses. The salinity of the aquifer varied spatially from 1367 to 8645 mg/l based on one hydrogeological condition, with the highest TDS (> 5432.5 mg/l, 25% of samples) at the central part of the study area. Temporally, the salinity changed slightly from 3754.3 mg/l (in 2014) to 4222.4 mg/l (in 2020). The cession of illegal wells, pumping control, and excavation of formed salts have a noticeable impact on salinity (mediate the increase in salinity) and ions. However, about 61% of the studied samples can be considered unsuitable for irrigation owing to salinity and can harm plant yield. The heavy metals studied (Fe, Mn, Cu, Pb), except Cd, were within the permissible limit for irrigation water. Finally, it is proposed to construct desalination stations to enhance water quality for irrigation in the study area and set up many companies for salt extraction.

Environmental application of three different talc deposits toward the removal of hexavalent chromium ions Cr(VI) from aqueous solution as simulated polluted water was investigated. Three talc samples (T1, T2 and T3) were used from Wadi Atshan area, Eastern desert, Egypt. The affecting parameters, such as pH, contact time, solution pH and the dosage, were studied during the progress of the adsorption process of chromium (IV). The results showed that a contact time of 65 min for T3, 80 min for T2, 85 min for T1 under optimum condition at pH 7 at 25 °C. The adsorption capacity for the removal of Cr(VI) using the three samples T1, T2 and T3 was evaluated to be 78%, 86% and 97%, respectively, under optimized conditions utilizing 1.0 g/L of the adsorbent. Characterization of the three talc samples was performed using XRF, XRD and FTIR analyses in order to assess the physicochemical properties of the adsorbents. This approach provided new class of adsorbent as highly efficient materials for Cr(VI) removal based on talc deposits which possess some privileges such as availability of the natural resources that makes the process to be low cost and simple.

Toxic elements behavior in Egyptian soil need more studies for the enhancement of soil quality and human health protection. The current study focuses on the mobility assessment of chemical species of As, Pb, Cr, Ni, Cu and Co in soils due to anthropogenic emission using sequential extraction (SE) and risk assessment code (RAC). Generally, the studied soils are alkaline calcareous loam soil. It has a low organic matter (OM) that ranges from 1 to 3.8% and is enriched with As, Pb, Cr, Ni, Cu and Co, which preferentially accumulate in soil clay and silt fraction. SE revealed that the non-residual (bioaccessible) fraction contains about (70.7%) As, (65.2%) Co, (58.8%) Cr, (28.4%) Cu, (6.8%) Ni and (64.5%) Pb, indicates the risk of pollution with As, Co, Cr, and Pb. RAC values indicated a high risk of soil pollution with As, medium risk of Co and Pb, low risk of Cu and Ni, and no risk of Cr. The results pointed out the geogenic source of Cr, mixed source of Co, Cu, and Ni and the anthropogenic source of As and Pb. The spatial distribution analyses of these metals indicated the role of urbanization, traffic, and industry on the releasing of toxic metals into the environment.

ASSIUT District represents an important part of central Nile Valley. It is a complex district containing many big industries, urbanization and agricultural activities. These activities can lead to the pollution of agricultural soil with toxic heavy metals. The aim of this work is the assessment of potential risks of these metals in soils using pollution indices; Enrichment Factor (EF), Index of Geoaccumulation (I-geo), Contamination Factor (CF), Ecological Risk Factor (E-r), Degree of Contamination (C-d), Pollution Load Index (PLI) and Potential Ecological Risk Index (PERI). The present study calculated the mentioned indices for eight heavy metals; As, Cd, Co, Cr, Cu, Ni, Pb, and Zn. Pollution indices calculations revealed that the investigated area can considered generally moderately polluted with the studied heavy metals. The emission of heavy metals from the factories as well as agricultural practices, urban runoff and sewage stations in the zone may be the source of that pollution. Consequently, control methods must be functional to the area adjacent to the factories to diminish the pollution. Finally, the studied cultivated soils showed low pollution than other cultivated soils in Australia, Canada, Germany, Tanzania, Netherlands, USA, as well as other areas in Egypt.