STUDY OF CHEMICAL POLLUTION IN SEDIMENT CORES FROM THE NADOR LAGOON (MOROCCO). ORGANIC AND INORGANIC CONTAMINANTS

The north of Africa is currently experiencing a great deal of economic development, which often, as confirmed by many examples, brings about the risk of pollution by toxic chemicals. The Nador Lagoon, the subject of several environmental studies, is located on the northern coast of Morocco. This lagoon is a great point of interest for the natural environment and for the increasing anthropogenic pressure due to adjacent businesses. This work aims to obtain further information about the status of contamination of this lagoon through analysis of sediment cores taken in June 2009. Chemical analyses were carried out of persistent organic compounds (POPs), in particular Polychlorinated biphenyls (PCBs) and Polybrominated diphenyl ethers (PBDEs), as well as the elements of interest for the determination of inorganic contamination. This study addressed four sediment cores taken in some of the most interesting places of the lagoon. For measuring the lagoon sediment chronology the radionuclides 210Pb and 137Cs have been used. These also show the possible perturbation of sediments during the years. The sediment dating allowed us to choose the best cores for organic and inorganic chemical analysis. The organic contamination was detected mostly in one sediment core, taking into account the most important samples along the core; for the other three cores only the upper sediment samples have been analyzed. The inorganic contamination was detected in two complete cores. The experimental part concerning the organic compounds involved automatic systems for extraction and purification; the determination was carried out by HRGC-LRMS. The elemental analysis was carried out using analytical protocols already developed in the laboratory: digestion with acids by means of a microwave digester, sample dilution, and then ICP-MS has been used for the analysis. In addition, we used multivariate statistical approaches to develop the results of the analyses and obtain more information about the samples correlation and the origin of the pollution. The Nador lagoon seems to be a not really polluted environment. This analytical research shows the low contamination of the investigated area, moreover shows also the increasing pollution in recent years linked to growing human activity in the surrounding region.