Distribution and ecotoxicological assessment of trace elements and minerals in Nile Delta sediments using multitechnique analysis

Abstract

This study assesses heavy metal contamination, trace elements, and mineral composition in Nile Delta sediments, a region critical for agriculture and ecology. Sediment samples (n = 23) were collected from key urban, agricultural, and industrial zones using a Van Veen grab sampler to capture spatial variability. Analytical techniques included X-ray fluorescence for elemental composition, particle size analysis for grain size distribution, and X-ray diffraction coupled with Fourier-transform infrared spectroscopy for mineral identification. All analyses followed strict QA/QC protocols, including certified reference materials and triplicate measurements. Statistical analyses (Descriptive Statistics, correlation, PCA) were applied to interpret spatial patterns. The elements analyzed included trace metals and oxides of major elements. Pollution indices-Pollution Loading Index (PLI), Geoaccumulation Index (Igeo), Enrichment Factor, Contamination Factor, and Sediment Quality Guidelines-were used to assess contamination levels and ecological risks. Results showed transition metal concentrations ranging from 0.1 to 569.3 mg kg-1, with actual cadmium (Cd) concentrations of 1.0-4.3 mg kg-1. The contamination degree ranged from 9.47 to 23.10, indicating localized pollution. Sediments exhibited moderate nickel (Ni) contamination but were within safe limits for copper (Cu) and zinc (Zn). PLI values (0.18-1.09) indicated minimal contamination overall, except at sites E2 and G3. Grain size analysis revealed sand (3.56-95.49%) and clay (0.27-12.50%) variability, while mineralogical analysis identified quartz, calcite, aragonite, albite, microcline, and illite as dominant minerals. The study concludes that Nile Delta sediments are generally uncontaminated by heavy metals (supported by Igeo values), though localized contamination hotspots exist. This research provides novel insights into sediment contamination patterns, offering a critical baseline for environmental management.