The chemical oceanographic consequences of environmental restoration projects in the Golden Horn estuary (Marmara Sea, Turkey).

The input of industrial and domestic waste to the horizontal circulation in the Golden Horn Estuary of Marmara Sea has resulted in one of the most polluted estuaries in the past. Consequently, the dissolved oxygen concentrations in both the surface and bottom waters decreased toward to the estuary head during 1998-2005. In contrast, the total suspended solids content of the surface water decreased toward to the estuary mouth. However, construction of the operational collector system surrounding the estuary during the process of rehabilitation projects, combined with the opening of the middle pontoons of the Valide Sultan Bridge, resulted in gradually improved water quality of the estuary with a concomitant decrease in pollution. However, phytoplankton blooms and eutrophication persist especially in the innermost part of the Golden Horn in 2005. The region from the estuary mouth up to Camialti has a dynamic structure, and sufficient circulation seemingly occurs in this part of the Golden Horn.

Rehabilitation and water quality monitoring in the Golden Horn.

In this work, the oceanographic aspects of the Golden Horn and some results of the Golden Horn Rehabilitation Project are presented. The hydrographic structure of the Golden Horn responds rapidly to the conditions in the southern Bosphorus, which is especially true for the outer parts of the estuary up to the Valide Sultan Bridge (VS). West of this bridge which was blocked by the pontoons of the bridge, carries the major pollution load and is dependent on the underlying water and surface mixing, for its renewal. The dissolved oxygen concentrations were measured below the detection limit in the region between the VS and Eyüp-Sütlüce (ES) section during the majority of the measurement periods where H2S has been determined simultaneously until February 2000. Although the microbial contamination of the estuary stations is very high, decreases in the contamination at stations are observed. The highest concentrations are recorded at the ES-VS section and supported by Fecal Coliform data during the rainy months in general despite the operational collector system surrounding the estuary. An obvious decrease of pollution in comparison with the data of the previous years is clearly observed as an encouraging result of the rehabilitation efforts achieved so far.