TOWARDS OPTIMUM MANAGEMENT OF TOTAL SUSPENDED-SOLIDS IN A COASTAL SEA- THE CASE OF IZMIT BAY, MARMARA SEA

The distribution and transport of total suspended solids (TSS) is cons idered in order to propose the strategy which, when implemented, would lead to compliance with the water quality criterion. Currently, most of the water in Izmit bay has a TSS concentration in excess of the leg al maximum of 30 mg/L TSS. Modelling and simulation shows that the maj ority of the TSS does not originate from the known land based sources but probably represents phytoplankton. Since excessive quantities of N and P are discharged into the bay, sometimes the growth of phytoplank ton is limited by the natural silicate content of the water. However, it is found that most of the phosphorus discharged from land based sou rces is in fact utilized by the phytoplankton. Hence, reduction of the TSS concentration to the legal limit can be achieved by decreasing ph osphorus sources. If the majority of total organic carbon emanating fr om land based sources were removed, this would imply a considerable de crease in phosphorus inflow. It is suggested that waste waters from re sidential communities and the remaining industry should be treated and released to the layer below the halocline using one outfall in the ea stern part and one or several outfalls in the central part of the bay.