The geochemical characteristics of the surface sediments of the Ambarli Port in Istanbul providing service for over 43.000 ships in the last decade are basically unknown. In this study, The distribution of total carbonate and metals in sediments was investigated and geochemical forms of the sediment-associated metals assessed to identify their possible sources. Metal contamination levels of sediments were evaluated with the aid of enrichment factor (EF) and index of geoaccumulation (I-geo) calculations. The degree of pollution in surface sediments yielded the I-geo ranking: Zn > Pb> Cr > Cu > As > Fe > Ni=Al >V, essentially not revealing pollution by Al, As, Fe, Ni and V. The highest Igeo and EF levels of Cr, Cu, Ni and Zn were found at the nearest station to Ambarli Port, indicating port activities as the source. Sequential selective leaching tests confirmed that As, Cr and Fe were mostly found in the residual phase, whereas Cu, Ni, Pb, V and Zn were mainly associated with the non-residual phase, possibly indicating the potentially higher mobility of the latter ions than those inherited from parent geological material. Based on statistical approaches, anthropogenic and natural geological factors were identified controlling the heavy metal variability in the sediments. This research is the first of its kind ever carried out in the Ambarli Port Area of Turkey.