Bomb fall-out 236U as a global oceanic tracer using an annually resolved coral core

Anthropogenic 236U (t½=23.4 My) is an emerging isotopic ocean tracer with interesting oceanographic properties, but only with recent advances in accelerator mass spectrometry techniques is it now possible to detect the levels from global fall-out of nuclear weapons testing across the water column. To make full use of this tracer, an assessment of its input into the ocean over the past decades is required. We captured the bomb-pulse of 236U in an annually resolved coral core record from the Caribbean Sea. We thereby establish a concept which gives 236U great advantage - the presence of reliable, well-resolved chronological archives. This allows studies of not only the present distribution pattern, but gives access to the temporal evolution of 236U in ocean waters over the past decades.

► This is the first ever annually-resolved record of 236U from global fall-out. ► We demonstrate the usefulness of 236U as oceanic tracer using coral cores. ► Using the record a value for the total global fall-out of 236U has been determined.