No abstract

In order to evaluate the contamination of the Moroccan Mediterranean coasts by persistent organic pollutants we studied hydrocarbons and linear alkylbenzenes in bivalve tissues (cockles) collected seasonally from several points along the western Moroccan coasts in the Mediterranean Sea. Two fractions corresponding to non aromatic and aromatic hydrocarbons were analyzed by GC/FID and GC/MS. Non aromatic hydrocarbon concentrations vary in the range of 24.1 - 2731 μg/g dry weight (dw) while total n-alkanes vary from 2.2 to 68.2 μg/g. Few exceptions were noted with values up to 243 μg/g (dw), which is high compared to other Mediterranean sites. The presence of an important unresolved complex mixture (UCM) indicated a significant petroleum contamination, confirmed by the identification of 17α(H), 21β(H) hopanes. Biogenic contributions were also detected within the n-alkane distribution (n-C₁₇, n-C₁₈, n-C₂₇, n-C₂₉, n-C₁₇, /Pr, n-C₁₈, /Ph) and by the presence of alkenes. C₁₃, and C₁₄, linear alkylbenzenes were found at concentrations of 478 - 1954 ng/g. and point to pollutant inputs from wastewaters. Polycyclic aromatic hydrocarbons were present in low concentrations below the GC detection limit. The observed seasonal and spatial variations were linked to the magnitude of inputs from marine and land-based pollutant discharges

Résumé :Les concentrations des hydrocarbures non aromatiques ont été déterminées au niveau des eaux de surface (matière particulaire) de la Méditerranée Marocaine Ouest (Frange littorale Kabila-Kaâ Srass) afin de déterminer l'état de la qualité des eaux de baignade vis-à-vis de la contamination par les hydrocarbures. Ainsi, les hydrocarbures totaux ont été extraits et fractionnés sur colonnes de silice en hydrocarbures aromatiques et hydrocarbures non aromatiques. Cette dernière fraction analysée par des techniques chromatographiques, montre des concentrations importantes (HNA: 0,78-68,13 µg/l) comparativement à d'autres endroits en Méditerranée.L'étude qualitative basée sur l'analyse des différents indicateurs géochimiques (n-alcanes, hopanes, isoprénoides, UCM, etc.) a permis de mettre l'accent sur la nature biogénique des apports, principalement continentale avec une faible présence de la trace des apports pètrogèniques.