Abstract

Tangiers bay, located in the extreme west of the Mediterranean Sea, and in the north west of Morocco, receives various pollutants through the Mghogha canal from urban and industrial rejections of Tangiers city. This survey was focused on physicochemical and geochemical characterization of the more exposed sites situated on Mghogha canal and on the bay coastline. Physicochemical analysis (Temperature (21 - 23°C), pH (6 - 7.5), suspended matters (70 – 300 mg/l), dissolved oxygen (1.15 - 4.5 mg/l), chemical and biochemical demands of oxygen (345 – 975 m/l and 55 – 245 mg/l respectively)) showed an important pollutant load in samples taken from Mghogha canal. This finding has been confirmed by geochemical analysis results (total organic carbon (1.5 - 2.7%), Rock-Evals pyrolysis (S1:0.52 - 2.10 and; S2:3.68 - 18.98 mg/g) and extraction of hydrocarbons (1.55 - 10.45 mg/g and 19mg/l)). The water quality does not meet the hygienic quality classification of the main local beaches allowed for public swim, in accordance with Moroccan norm (NM 03.7.200 for quality surveillance of swimming waters). The high pollution load drained by the primary effluent from Tangiers district have prompted the conclusion of a city’s wastewater treatment project to lower pollutant levels by 50%, which is still insufficient for a fragile ecosystem such as the Mediterranean.

Key words: Physicochemical analysis, geochemical analysis, urban rejection, organic load, Mghogha canal, Tangiers bay