Ecological risk assessment and spatial distribution of some heavy metals in surface sediments of New Valley, Western Desert, Egypt

Abstract The southern New Valley consists of three main oases, Farafra, Dakhla and Kharga Oases in the Western Desert, Egypt. Sediment samples collected, from land (24) and in ponds (23), from the three oases were used to evaluate the potential ecological risk and spatial distribution of Zn, Cu, Pb and Cd, also to verify whether the sources of pollution were by human activities or an accumulation of different parameters from the land near the ponds. They were also collected for grain size analysis including those of sand and mud percentages along with the mean, organic carbon, total carbonate, total phosphorus and Iron values. Sediment enrichment factor (EF) showed that the variation values were from moderate to minor enrichment. The Geo-accumulation index calculations ( I geo ) proved that the investigated areas could be classified as unpolluted with the exception of Mute 13 and HO2 which were moderately polluted by Cd, while Ras was strongly polluted by Cd. HO1 and Ras revealed that they were a moderate to considerable ecological risk, respectively. Mean ERM quotient (MERMQ) reflected that the surface sediments of HO3 and Mute 5 have 21% probability of toxicity.