Records of anthropogenic pollution in sediment of Gemlik Bay (Marmara Sea, Turkey) during the last 15 years

ALPAR Ş. B., Ünlü S., Kırbaşoğlu Ç.

General Assambly of the European Geosciences Union, Austria, 1 - 04 April 2006

  • Publication Type: Conference Paper / Full Text
  • Country: Austria
  • Istanbul University Affiliated: Yes


The organic carbon contents, polycyclic aromatic hydrocarbon concentrations and
textural composition of a total of 72 surficial sediment samples (from 6 to 320 m
water depths) have been studied to assess the relative importance of productivity, organic
carbon accumulation/preservation and main controls on the distribution of antropogenic
pollution buried within the modern sediments across the Gemlik Bay, which is
the second most polluted hot spot in the Marmara Sea; a semi-enclosed sea connecting
the Black Sea to the Aegean Sea via the Bosphorus and Dardanelles straits. Contrary
to low values in the outer basin, the organic carbon content is relatively high within
the bay. Its highest values are distributed in the middle of the basin, inner Gemlik Port,
Karasu River which is the most important fresh water discharge in the west, and a resort
area Trilye. Highly-populated eastern and southern coasts are mainly influenced
by rapid ecotourism development, direct discharges from rivers, surface run-off and
drainage from port areas, domestic and industrial effluent discharges through outfalls
and various contaminants from ships. Bathymetric features and the associated hydrodynamic
processes seem to play an important role in the enrichment of organic carbon.
Organic carbon contents show consistency with the sediment textural characteristics
and the oxygen deficiency observed in Gemlik Bay. The results were also compared
with two sets of historical data covering the periods of 1990 and 1997. On the basis of
the percent of area distribution, organic carbon contents indicate an increment through
the years. It is both striking in the sedimet recovered from deeper waters where the
currents are weaker and in coastal areas where the anthropogenic dense nutrient and
organic mater inputs are high. Production, accumulation and preservation of organic
matter in the bay is believed to have been mostly affected by the inflow of relatively
organic-rich Black Sea waters, by the rivers, and by inflow of organic-poor lower layer.