Environmental Conditions of the Coastal Waters of Southern Corinche, Jeddah, Eastern Red Sea: Physico-chemical Approach

Al Khumra Sewage Treatment Station is the most important of all the wastewater treatment plants in Jeddah, eastern Red Sea. Prior the year 2000, the semi treated sewage was disposed at the Southern Corniche area, south of the city. The sewage outlet was situated at about 1 meter above the sea surface and sewage was dumped into a semi closed lagoon to limit its dispersion southwards by the prevailing northwesterly wind. During the year 2000, the effluent was transferred about 3 km south of the old one. The new effluent is placed just on the edge of the fringing reef, ~500 m from the shore line, at about 20 m below the surface. In order to measure the impact of the new disposal conditions on the Southern Corniche area, the physical and chemical properties of the surface water (salinity, dissolved oxygen, dissolved nutrients, SPM, Chl-a, DOC and POC) were measured during April 2003 and January 2004 and compared to the results of a previous study carried out in 1999. The results of the present study indicate that the area has suffered a measurable modification. While concentrations of nutrients did not suffer great modifications, the relative distribution of inorganic nitrogen constituents and the phosphorus /nitrogen ratio have suffered dramatic modifications. The distribution of all the parameters indicated that the new effluent is a point source for all the analyzed parameters. The transfer of the effluent to the open coastal area, while facilitating the dilution of the discharged sewage, is suspected to enhance the spread of the different contaminants over larger areas and may represent a potential threat to the marine life and the health of the humans.