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Abstract The last decade has brought a significant increase in research on the environmental problems, especially, the contamination of earth’s ecosystem by potentially toxic heavy metals. Due to the health impacts of pollution from the ingestion of heavy metals via respiration, food and drink water. The WHO estimates that about a quarter of the diseases facing mankind today occur due to prolonged exposure to environmental pollution. The present study is a continuation to the aforementioned efforts. It deals with mineralogy, geochemistry and environmental geochemistry of the Egyptian phosphorites, phosphatic fertilizers, agricultural soils and mudbrick samples, to evaluate their content of environment-toxic elements and discuss the environmental impact of application of phosphorites and their fertilizers in accumulation of toxic metals in agricultural soil. The results of the study conclude in the following sentences. 1- Petrographically, the Upper Cretaceous phosphorite, at the main productive localities (Red Sea, Nile Valley and Abu Tartur), composed: phosphatic grains, non-phosphatic grains, and cements. There are two basic types of phosphatic grains observed in the studied samples; skeletal and diagenetic grains. The non-phosphatic grains contain quartz, organic matter, ferruginous material and calcareous biogenic debris such as foraminifera and pelecypod shell fragments. The intergranular pore-spaces of the Duwi Formation phosphorites are mostly cemented by silica and carbonate materials. 2- The mineralogical analysis of the phosphorites indicates that francolite is the main phosphatic minerals. The major non-phosphatic minerals are quartz, calcite, pyrite and dolomite. Traces of glauconite, 120 gypsum, pyrite and some clay are also recorded as secondary constituent. The CO2 content of the apatite in all studied phosphorite samples was determined semi quantitatively from their x-ray diffractograms according to the equation of Gulbrandsen (1970) and the new equation that has suggested by Schuffert et al. (1990). 3- The mineralogical composition of the agricultural soil indicated that montmorillonite is the dominant clay mineral, followed in abundance by kaolinite, vermiculite and little amount of illite. While the non-clay minerals composed of quartz and feldspars minerals. 4- The results of the grain size distribution reveal that the investigated soil samples are mainly silt loam with lesser samples of silt, sandy loam and loam texture. 5- The studied agricultural soil and mudbrick samples are slightly to moderately alkaline soils with pH ranging from 7.75 to 8.32. The agricultural soil salinity optimum to grow any plants and it classified under category non-saline (EC < 2 dS/m). The continuous evaporation and lime paint salts that cause increasing in mudbrick salinity. The soil samples are enriched in its total organic matter content. 6- The geochemical data indicate that the Egyptian phosphorite classified as medium-grade ore depending on their P2O5 content. The total average of P2O5 content is 25% in Red Sea samples, 21 Nile Valley and 20 in Abu Tartur. The P2O5 content enriched through the fertilizer manufacturing to reach 28% in mono-super phosphate and 34% in tri-super phosphate. The Egyptian phosphorites composed CaO, SrO, Fe2O3, MnO, Na2O, MgO, SiO2, Al2O3, K2O and SO3 similar to the world phosphorites. Silicon, aluminum and iron oxides are the highest major oxides in soil samples. 121 7- The phosphorites and phosphatic fertilizers composed a significant amount of environment-sensitive metals as As, Se, Cd, U, Cu, Co, Pb and Ni. Abu Tartur phosphorites are depleted in U content in compare to the phosphorite of Nile Valley and Red Sea. Such metals are transfer to the fertilizers. The total toxic metals in Egyptian phosphorites are lower than. |