Records of mitigation measures in the sediments from an urban estuary, Turkey

ECSA54, Coastal systems under change: tuning assessment and management tools, Sesimbra, Portugal, 11 - 16 May 2014, pp.90

Heavy metals were monitored in surface sediment from an estuary, the Golden Horn, Istanbul. This urban

estuary has 3 distinct water masses; a very thin freshwater mass, brackish Black Sea water and more saline

Mediterranean water. Rapid urban growth and uncontrolled industrial development (1950-1985), however, led

to tremendous pollution of its water and thick layers of anoxic sediments. Due to ecologically unlivable

conditions it became the main subject of many top priority larger and smaller projects. However, these changes

remained far from initiating a large-scale transformation in the area. At the end of 2012 the municipality started

to transport Black Sea’s clean but more saline (17 psu) water to the Golden Horn through a 14 km tunnel. This

makes surface water denser, easily carrying suspended particulates much farther from the tributaries. As

sedimentation is a continuous process, the sediment bed is probably the best medium to store records about

the pollution history. In order to assess the sediment quality and to highlight the anthropogenic contributions to

heavy metal distributions, selected heavy metals in surface sediments were studied in 2012 and 2013. Multiple

chemometric approaches indicated three different regions along the estuary and revealed natural and

anthropogenic sources with moderate levels of Cu, Zn, Pb and Cd. Mitigation measures conducted at the

estuary affect transport processes but not all over the estuary.