Environmental Risk Assessment and Sources of Potentially Toxic Elements in Seawater of Jazan Coastal Area, Saudi Arabia

Abstract

High levels of potentially toxic elements (PTEs) in water bodies negatively affect the biota of aquatic ecosystems and surrounding environments. A risk assessment investigation of the levels and distribution of PTEs in the seawater of the Jazan coastal area, southwest Saudi Arabia, was conducted. Thirty-two surface seawater samples were collected, and contamination (Cd) and heavy metal pollution (HPI) indices, as well as multivariate statistics, were applied. The average PTE levels (µg/L), in descending order of magnitude, were Cu (2.56), Pb (2.27), Ni (1.30), Cr (1.28), Zn (1.04), Sb (0.36), Co (0.22), and Cd (0.06). A fluctuating pattern without a fixed direction was detected in the spatial distribution of these metals, with increased pollution being linked to high metal levels as shown by some samples. The HPI indicated low pollution in 50% of the samples and medium pollution in the remaining 50%, whereas the Cd indicated low contamination with PTEs. The absence of significant correlations between pairs of metals indicated different sources of metal pollution. Lithogenic sources are implicated in the supply of Co, Ni, Pb, and Sb, whereas Cr was mainly derived from an anthropogenic source, and combined lithogenic and anthropogenic sources are believed to have contributed Cu and Zn to the area. It is proposed that urbanization, agriculture, and industry are among the potential anthropogenic sources of pollutants on the Jazan coastline. Soils generated on the undifferentiated Quaternary rocks along the investigated area are the main lithogenic sources.