ABSTRACT
The outlet of the main-sewer from the Marseilles conurbation takes place on the creek of Cortiou (south of Marseilles), at the sea-surface. On average the discharge is about 9 cubic meter/sec per day. The sewage is not pretreated except for a hasty oil-separation and the elimination of large items such as paper, cardboard, plastics, tins, bottles, small pieces of wood, etc., which are retained by a screen system. Four sampling stations were chosen in the investigated area. The plume chiefly drifts from east to west along the shoreline due to the predominant wind regime and also due to the general cyclonic flow of the Western Basin of the Mediterranean Sea, a part of which enters the funnel between the shore and the chain of small islands. Toxic substances are progressively concentrated from the food which comprises living and inanimate materials as well as dissolved substances.
