Assessment of heavy metal contamination in Gulf of Gabès coastland (southeastern Tunisia): impact of chemical industries and drift currents

The present work investigates the aspects of anthropogenic contamination in the littoral zone of Gabès city (Tunisia). Special interest was addressed to the effects of chemical industries and coastal dynamics on the pollutant input and distribution along the coast. As a first step, 16 superficial sediment samples were collected including 8 items on the beach and 8 in the intertidal zone. Subsequently, geochemical and granulometric analyses were carried out. Heavy metals (Zn, Cu, Pb, and Cd) as well as sulfates, phosphorus, chlorine, sodium, calcium, bromine, and the percentage of the fine fraction were quantified in all samples. Two approaches were adopted for the interpretation of results. The first descriptive approach revealed that the coastline is subjected to fairly significant anthropogenic pressure. Results showed that the littoral zone is highly contaminated by various toxic elements, notably heavy metals. It seems that the coastal dynamics have a major contribution in the transport and deposition of several contaminants. The second approach allowed identifying the potential origins of pollutants based on a principal component analysis. Results proved that the impact of releases from chemical industries is the most significant. More efforts are required to investigate the mechanisms of ion transfer and exchange between pollutants and the various media such as sediments, water, and air.