9. Metal Contamination Assessment in the Sediments of the Red Sea Coast of Saudi Arabia

Surficial sediment samples were collected from sixty stations between 23°N and 28°N latitudes in the northern Red Sea and were analyzed for 10 metals, namely Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, V, Zn and a metalloid, As. Based on mean concentrations, the order of abundance of the metals (dry weight) was: Fe (6320.61 mg kg⁻¹) > Mn (409.71 mg kg⁻¹) > Zn (38.76 mg kg⁻¹) > V (19.73 mg kg⁻¹) > Ni (15.92 mg kg⁻¹) > Cu (15.51 mg kg⁻¹) > Cr (14.6 mg kg⁻¹) > Co (6.53 mg kg⁻¹) > As (5.21 mg kg⁻¹) > Mo (1.06 mg kg⁻¹) > Hg (0.03 mg kg⁻¹). Arsenic was the only element to exhibit exceedance with 88% of the stations above upper continental crust concentrations (UCC) and 8% of the stations above threshold effect level (TEL). Sediment contamination assessment was carried out using the geoaccumulation index (I_geo) and enrichment factor (EF) and ecological hazard was assessed using the Adverse Effect Index (AEI), Potential ecological risk factor (ER) and Potential ecological index (RI). Hierarchical Cluster analysis (HAC), Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were used to group stations as “uncontaminated”, “minor enrichment”, “metallogenic enrichment” and “anthropogenic enrichment”.