Background and anthropogenic ionizing radiations are main sources of environmental radioactivity exposing human beings. Background radiation occurs as a result of cosmogenic and terrestrial radiation, while anthropogenic origins are man-made radiation. In this context, gross alpha and beta activity of sea sediment samples collected at 7 different stations in the research region (Şarköy and Mürefte) were analyzed using the low-background counter (Berthold, LB 770 10-channel α−β low-level counter). Also, the relationship between the abundance of radioactive isotopes and alpha and beta activity were discussed in this paper. As a result, the average gross alpha and beta activity was determined as 218.18 14.9 Bq kg -1 and 579.00 23.9 Bq kg -1 , respectively. Maximum gross alpha value in investigation area 301 15.9 Bq kg -1 (Şarköy Port), and the lowest value is 989 16.5 Bq kg -1 (Şarköy Port). When these values were compared with Bosna River results, both gross alpha and gross beta values were found to be high [3,4]. The main reason why gross alpha and beta concentrations are generally high is that the fertilizers used in agriculture contain uranium, thorium and their degradation products and natural 40 K.