Pollution sources and exchange trends of sea water quality in the Bosphorus

When all the pollutant sources which affects the Bosphorus straits are analyzed and compared, the leading pollutant factors are as follows: pollution loads from the Black Sea; discharges made from the wastewater treatment plants of Istanbul city, loads that are carried by the streams from the residential settlements of the city; loads caused by the maritime traffic and sea accidents in the straits of Istanbul. After examining the wastewater flow rate in the treatment plants of Istanbul, it is observed that approximately 80% of the wastewater is currently treated by the pre-treatment plants before being discharged into the sea. When the discharge waters of the wastewater treatment plants are analyzed, it is noticed that the discharge waters of the biological and advanced biological treatment plants are in conformity within the general standards imposed by the Regulations of the Control of Water Pollution, whereas the qualities of the discharge waters of the pre-treatment plants are at sometimes not concessive with these standards. In this study the results of the sea water quality researches of the years 1997 and 2004 made by ISKI have been compared and have resulted in improvement. The main parameters reflecting the sea water quality are dissolved oxygen, total suspended solids, total nitrogen, total phosphorus, chlorophyll-a, heavy metals (Pb, Fe and Mn), petroleum hydrocarbon, surfaced activated matter and fecal coliform bacteria. Conclusively when all the results are taken under consideration, the greatest change ratio observed is realized by total nitrogen concentrations and total phosphorus concentrations. Keywords: The Strait of Istanbul, pollution sources, exchange trends of sea water quality