Presenter: TLIG Nejia (Tunisia)

Description:
Since the establishment of the Chemical Group in the Gulf of Gabes, southeastern of Tunisia, polluted water has been discharged directly into the sea without any treatment, causing significant environmental threats. This work consists on a geochemical study of Boughrara lagoon localized in the south of Gulf of Gabes in order to identify the spatial variability and main source of heavy metals in surface sediments by conducting a multivariate statistical analysis assisted with GIS tools. Mineralogical and geochemical analyses were carried out in order to identify characteristics of surface sediment in this lagoon. X-ray diffraction analysis coupled with scanning electron microscopy allowed to deduce the mineralogy of samples and to identify the different types of minerals like pyrite, illite, smectite with dominance of quartz near the three streams. In addition, elemental concentrations of studied heavy metals like Cu, Zn, Co, Cd, Pb, Mn, Fe, Al and P were obtained by ICP-QMS, all these elements showed a significant concentration in the southwestern of the lagoon. A multiple quantitative geochemical indices were calculated to assess the sediment quality and to evaluate the environmental risk in this lagoon. By referring to background values, Boughrara lagoon is considered as highly polluted (high degree of contamination). Also Rare earth elements (REE) were calculated to trace the origin of mineral matter found in surface samples. A remediation action is urgently needed in Boughrara lagoon by building various sustainable coastal managements or reducing the amount of pollutants discharged into the lagoon, in order to protect the marine biodiversity in this area.