In this study, the natural and anthropogenic toxic metal pollution, and the general characteristics of lake sediments are investigated spatially and temporally. Three lakes are chosen in 2014 according to their origin from the Southeastern Black Sea-Sera Lake, Uzungol Lake, and Borcka Dam Lake. Four sampling campaigns are conducted during the four seasons: spring, autumn, winter, and summer. The elements lead (Pb), copper (Cu), zinc (Zn), nickel (Ni), and arsenic (As) are selected for investigation. The highest average toxic concentrations of Cu (498.46 mu g g(-1)), Pb (185.60 mu g g(-1)), and As (18.74 mu g g(-1)) were found in Borcka Dam Lake; however, those of Zn (435.00 mu g g(-1)) and Ni (143.42 mu g g(-1)) are found in Sera Lake. The highest metal concentrations are observed in autumn. Metal concentrations are determined by inductively coupled plasma mass spectrometry. The potential ecological risk index (RI) and geoaccumulation index (I-GEO) values are calculated for assessing sediment pollution. The assessment of sediments according to their potential ecological risk to the aquatic environment reveal that Cu contamination is a moderate risk in Borcka Dam Lake. According to I-GEO classifications, the highest I-GEO values are found in Borcka Dam Lake in autumn. Accordingly, the study area is determined to be highly contaminated with Cu and Pb. Cu and Pb can be considered as major contributors to ecological risk in these Southeastern Black Sea lakes.