Redionuclides such as U,Th,Ra, and Am [1] constitute a category of heavy metals in marine environment as they become and cause serious risks to human health and ecosystem [2]. They are generated from two differant sources: 1) natural sources which yield a constant activity level and 2) artificial sources which are caused by nuclear weapon tests, nuclear accidents, nuclear power plants . nuclear waste and so on causing a variation in the radioactivity level .
Increasing utilization of radioactive materials for industrial and medical purposes may cause contamination of radionuclides in the marine environment. Daughter decay products (Rn. Ra. Pu and Pb) from natural radioactive series Th-232 ,U-235 and U-238 and the others (K-40 and Ru-87) are mobilized and accumulated in the marine sediments .Components of the marine environment such as the appearance of the sediment. the organic content, the grain size and geochemical properties (properties of seawater). the benthos and the marine organisms could be affected by the accumulation of radionuclides in marine sediments .