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

Abstract

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