Heavy metal pollution in surface sediment and mussel samples in the Gulf of Gemlik Selma Ünlü & Sayhan Topçuoğlu & Bedri Alpar & Çiğdem Kırbaşoğlu & Yusuf Ziya Yılmaz Received: 9 March 2007 / Accepted: 29 August 2007 / Published online: 28 September 2007 # Springer Science + Business Media B.V. 2007 Abstract Sediment quality data provide essential in- formation for evaluating ambient environmental quality conditions. An evaluation is presented of heavy metal pollution, on the basis of statistical analysis of metal concentrations from the sediments of the Gulf of Gemlik, southeastern Marmara Sea, Turkey, which has been subject to high levels of pollution. The ranges for heavy metal concentrations (Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) at the <63 μm grain size were higher when compared with those obtained from >63 μm fractions. Not only large industrialized seaports but also resort areas throughout the Gulf are flagged as hotspots for elevated concentrations, generally higher compared to those from the other Turkish marine environment. The highest concentrations of Cr, Pb and Ni were measured in the outer part of the Gulf, while the highest con- centrations of Cu were documented offshore the main rivers. While the concentrations of Cr, Fe, Mn and Ni in some stations approach the severe effect level given in various sediment quality guidelines, the concentrations of the most human-related metals (Cd and Zn) in the mussels collected from the Port Mudanya were higher than the acceptable values for human consumption set by various healthy organizations. Keywords Heavy metals . Bottom sediments . Mussels . Mytilus galloprovincialis . Grain size . Pollution Introduction Heavy metal discharges to the marine environment are of great concern all over the world. Heavy metal concentrations in sediment, which is essential to the functioning of aquatic ecosystems, are many times greater than the same metals in the water column. The bioaccumulation of sediment-bound metals by benthic species is extremely important to the food webs and their eventual transfer back to man. There- fore sediments are used as environmental indicators to reflect the prevailing quality of marine or lake systems. Moreover, they permit the determination of metals even when the concentrations in water are undetectable with current methods (Gonçalves et al. 1994: Soares et al. 1999). The Marmara Sea is a semi-enclosed deep basin between the Mediterranean and the Black Sea. The contaminants are introduced through water way into Environ Monit Assess (2008) 144:169–178 DOI 10.1007/s10661-007-9986-6 S. Ünlü : B. Alpar Institute of Marine Sciences and Management, Istanbul University, 34116 Vefa Istanbul, Turkey S. Topçuoğlu (*) : Ç. Kırbaşoğlu : Y. Z. Yılmaz TAEK, Çekmece Nuclear Research and Training Center, P.O. Box 1, Atatürk Airport, 34149 Istanbul, Turkey e-mail: sayhantopcuoglu@yahoo.com