Radionuclides in the sediments were measured with a gamma spectrometer equipped with HPGe detector (Ortec GWl-120230 MJ-GWL). The energy and efficiency of the detector were calibrated with IAEA soil 6 reference material [9]. For statistical confidence. the counting time of marine sediment was optimized to 60.000- 80,000 s . The radioactivity was calculated by: