Radium, thorium, and uranium isotopes in the interstitial water from the Pacific Ocean sediment

The Ra, Th, and U isotopic concentrations were determined in the interstitial water expressed from a deep sea core of the eastern equatorial Pacific. The isotopes 226Ra, 228Ra, 230Th, and 228Th are higher by 1 to 3 orders of magnitude than their concentrations in seawater. Radium release from sedimentary phases with migration into the water column is indicated. The results are also compatible with the excess 228Th (relative to 232Th) found in authigenic deep sea minerals.