ABSTBACT: The upper 90 cm of Black Sea basin sediment with an aereal extension of 2,96X105 km2 has an U8O8 content of 6.7X106 tonnes, Plankton is the prime agent for uranium to accumulate over the past 5,000 yr. Energetically self-sufficient burning of the top 1-m strata will lead to U8O8 concentrations in the order öf 100 g per tonne ash.