The sediment chronology was determined using Lead-210 (Pb-210) dating method in Gulbahce Bay. Sediment cores were obtained using gravity core sampler from hydrothermal area and also from reference point and surfical distribution of Polonium-210 (Po-210) was investigated in the study area. The average of surfical concentration of Po-210 was found as 175.25 +/- 3.80 Bq kg(-1) in the hydrothermal area which was higher than the reference point value of 133.20 +/- 3.30 Bq kg(-1). Sedimentation rates in Core reference point (RN) displayed an increase till the year 1942 and a decrease afterwards, sedimentation rates in any core from hydrothermal area have not exhibited any continuous increase or decrease. The Pb-210 fluxes measured from core inventories are close to each other. Average enrichment factors for Cu, Cd, Sr, Zn, Cr vary between 20.35 and 12.18 indicating that the sediments have been contaminated with these metals in the reference point. Maximum enrichment factor values for Cr, Cu, Zn, Ba, Sr, Ni, Co vary between 22.91 and 11.42, implying that the sediments in hydrothermal area have been contaminated with these metals. (C) 2011 Elsevier Ltd. All rights reserved.