The vertical distribution of cesium 137 and strontium 90 in the oceans

Oceanic mixing rates derived from published measurements of Cs137 and Sr90 are at least a factor of 5 greater than those based on measurements of cosmic-ray produced C11. In an attempt to resolve this anomaly, samples were obtained by the staff of the Columbia University research vessel Vema from which Cs137, Sr90, C14, Ra260, H3, total Sr, total Cs, and total Ba could be determined. The techniques used for the Cs137 and Sr90 measurements are described and the results are presented for these two isotopes in profiles from the Caribbean, the eastern South Pacific, the Antarctic, and the North and South Atlantic oceans. Contrary' to the evidence for rapid transport of these isotopes to depths beyond 1000 meters found in both the Atlantic and the Pacific oceans by previous investigators, no measurable amounts of Cs137 or Sr90 were found in the majority of samples taken below 300 meters. The observed distribution is more in keeping with that of natural radiocarbon.