Evaluation of Contamination Status, Ecological and Human Health Risks of Heavy Metals in Sediments North of Safaga Bay along the Red Sea, Egypt

Abstract

This study aimed to estimate the contamination levels and potential risks of some heavy metals (Al, Fe, Mn, Zn, Cu, Co, Ni, Pb, and Cd) in surface sediments collected from northern Safaga Bay along the Egyptian Red Sea coast. The concentrations of the studied metals decreased in the following order: Al> Fe> Mn> Zn> Pb> Ni> Co> Cu> Cd, with average concentrations of 4537.12±5025.35 mg/kg dw, 678.91±342.97 mg/kg dw, 136.09±117.00 mg/kg dw, 40.38±11.92 mg/kg dw, 17.19±3.97 mg/kg dw, 12.74±3.01 mg/kg dw, 9.24±2.19 mg/kg dw, 2.98±1.24 mg/kg dw, and 2.46±1.20 mg/kg dw, respectively. Results of sediment contamination indices such as contamination factor (CF), degree of contamination (C d ), modified degree of contamination (mC d ), metal pollution index (MPI), enrichment factor (EF), potential contamination index (PCI i ), sediment pollution index (SPI), and potential ecological risk index (RI) showed that the sampling sites are rated between uncontaminated and highly polluted. According to sediment quality guidelines (SQGs), adverse biological effects of heavy metals have sometimes been associated with Cd, and more rarely with Zn, Cu, Ni and Pb. Interestingly, sediment quality indices indicated the critical hazards of Cd to the biological system in the study area. The results of the assessment of risks to human health by heavy metals in sediments demonstrated that their exposure did not pose any carcinogenic risks. Statistical analyses revealed the interaction between geochemical variables, the distribution of heavy metals, as well as the proximity to pollution sources and flowing water.