Geochemistry and environmental effects of potentially toxic elements, polycyclic aromatic hydrocarbons and microplastics in coastal sediments of the Persian Gulf

Coastal areas are critical parts of the Persian Gulf with regard to high populations and economically driven activity. They pose major concerns because of the presence of toxic chemicals, and hence harmful effects on marine ecosystems. In this study, 14, 15 and 12 coastal sediment samples were collected in Bushehr province and analyzed, respectively, for potentially toxic elements (PTEs), polycyclic aromatic hydrocarbons (PAHs) and microplastics (MPs). The results showed that almost all PTEs were not significantly enriched. Most elements exhibited their highest levels at stations close to urban areas and along the pathway of ships and boats. Based on enrichment factor and statistical evaluations, two main sources of trace elements were identified: anthropogenic (Mo, Cu, Pb, As and Sb) and geogenic (Zn, Ni, Co, Mn, Fe, Cd, Cr and Al). Regarding MPs, a total of 577 pieces were observed with sizes ranging between 500 and 1000 mu m. The dominant shape of the MPs was fibrous with the dominant colors being white and black. The concentration of total PAHs were fairly low in the sediments, with their source determined to be pyrogenic in origin.