Sediment Quality and Potential Toxicity Assessment in Two Open/Semiclosed Mediterranean Sea Areas: A Case Study of Sfax Coast (Tunisia)

The Gulf of Gabes (southeastern Tunisia), characterized by the abundance of halieutic resources, is nowadays facing strong anthropogenic pressures. This paper aims to assess and compare metallic pollution in two open/semiclosed areas bordering the coastline of Sfax (a part of the Gulf). The first area covers the outlet zone of many anthropogenic effluents of urban Sfax, whereas the second area, located at a distance of 15 km from the first one, was selected as being representative of numerous semiclosed areas bordering the Gulf that have served for harvesting clams. Spatial distribution of selected heavy metals (Cd, Pb, Zn, Cu, and Fe) coupled with chemometric approaches (enrichment factor, contamination degree, mean-ERM-quotients, and cluster analysis) were used as tools for the assessment of metallic pollution. The obtained results showed that metallic pollution is higher in the semiclosed area despite the absence of neighboring anthropogenic sources, probably because of the relative importance of both autochthonous organic matter and biota. The computed potential ecotoxicity demonstrated moderately high values in this area, testifying to a menaced biota that is prone to more affecting hazards if significant active measures are not taken.