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 considered 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 legal maximum of 30 mg/L TSS. Modelling and simulation shows that the majority 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 phytoplankton is limited by the natural silicate content of the water. However, it is found that most of the phosphorus discharged from land based sources is in fact utilized by the phytoplankton. Hence, reduction of the TSS concentration to the legal limit can be achieved by decreasing phosphorus sources. If the majority of total organic carbon emanating from land based sources were removed, this would imply a considerable decrease in phosphorus inflow. It is suggested that waste waters from residential communities and the remaining industry should be treated and released to the layer below the halocline using one outfall in the eastern part and one or several outfalls in the central part of the bay

Eutrophication of the Izmit Bay, Marmara Sea

The elongated Bay of Izmit is one of the most heavily polluted semienclosed basins in Turkey. From systematic data obtained during field studies between 1984 and 1988, it is clear that two distinct water masses are present throughout the year. The brackish water which originated in the Black Sea forms a 10 to 15 m thick surface layer. Its salinity and temperature vary from 22-24 ppt and 20-24 °C in summer, to 26 ppt and 7 °C, in winter. Marine water, which arrived from the Mediterranean, underlies the permanent pycnocline and has much more stable properties: salinity and temperature ranges are 37.5-38.5 ppt and 14-15 °C, respectively. Since the phytoplankton production is limited to the upper layer, including the halocline, nutrients have low surface concentrations in productive seasons and a higher concentration in winter. There is a sharp concentration increase in the halocline to high, almost constant, value in the lower layer. Phytoplankton biomass, in terms of chlorophyll-a concentration, has been found to be as large as 33 pg/L during spring in the more eutrophic inner part of the bay. In March 1988, the production reached the peak value of 3.3 g C/(m2 day) with the mean annual rate of at least 2 to 4 times larger than in the Marmara and Black Seas. Dissolved oxygen concentration decreases in the halocline and varies seasonall