Anthropogenic Contributions to Heavy Metal Distributions in the Surface and Sub-surface Sediments of the Northern Coast of Sfax, Tunisia

Eight selected heavy metals (Cu, Zn, Pb, Cd, Cr, Mn, Fe and Al) in surface and sub-surface sediments in the northern coast of Sfax (Tunisia) were studied in order to assess the sediment quality and to highlight the anthropogenic contributions to heavy metal distributions in the two study sediment levels. Multiple chemometric approaches based on Geographic Information System (GIS), Enrichment factors (EFs), geoaccumulation index (I geo ) and Principal Component Analysis (ACP) were applied. Enrichment factors (EFs) and principal component analysis (PCA) revealed two distinct groups of metals. The first group attributed to Mn, Fe and Al that were derived from natural sources, and the second group contained Cu, Zn, Pb, Cd and Cr mainly originated from man-made sources. The contribution rates of these later in terms of the sediment’s enrichment exceed 98%. The geoaccumulation index (I geo ) values explained that only Zn, Pb, Cd and Cr can be considered as moderate to extreme pollutants both in surface and sub-surface sediments.