ASSESSING OF ANTHROPOGENIC INPUTS IN THE SURFACE WATERS OF THREE COASTAL MARINE AREAS UNDER CONTRASTED POLLUTION INFLUENCES IN THE GULF OF GABES, TUNISIA

Physical, chemical and biogeochemical variables were studied in the surface waters of three coastal areas characterized by different degrees of pollution (the Sfax Northern (NC) and Southern coasts (SC) and the Ghannouch area of Gabes (GA)) during October and November 2014 in order to identify pertinent tracers of anthropogenic inputs and depict their spatial distribution. The SIAPE (SC) and the GCT (GA) were the main sources of inorganic pollutants such as PO43-, HCO3-, Cl- and SO42-. High contents in total polyphenolic and flavonoid compounds were observed in the SC due to the olive oil treatment waste water released from margins, notably contributing to the increase of COD concentration. The BOD5/COD ratio was < 0.5 for 50% of stations; it thus underscored a pollution of chemical origin. The COD/BOD5 ratio was > 3 just for 30% of the SC stations which underlined an organic load resistant to biodegradation due to the high content in polyphenolic compounds.