Measurement of Ra228 and Th228 in sea water

The first measurements of radium 228 in the ocean are reported, and the analytical methods of determining Ra²²⁸ and Th²²⁸ are discussed. Measurable excesses of both Ra²²⁸ and Th²²⁸ relative to the Th²³² exist in the ocean. Ra²²⁸ should prove a valuable tracer for studies of water movements. Its 6.7-year half-life makes it applicable to processes with a time scale of 3-25 years.