241 americium in Mediterranean surface waters

It is stated that little information is available on the occurrence of 241/Am in sea water, except for data obtained in some special areas such as in the vicinity of a nuclear reprocessing plant, for example, Windscale, UK, or in areas of close-in fallout from nuclear explosion tests. This is largely due to analytical difficulties involved in determining low concentrations in open ocean water. However, since in the near future the inventory of 241Am in radioactive wastes from nuclear fuel reprocessing is expected to exceed that of Pu it is important to start obtaining baseline data for this isotope in oceanic waters now in order to be able to follow the future trend of concentration changes, if any. The analytical procedure adopted is described. It involved coprecipitation of the 241Am together with Pu isotopes with mixed hydroxides and carbonates of Ca and Mg, and a second coprecipitation was carried out scavenging with Fe3+. The 241Am was purified from Pu and other interfering α-emitters by ion exchange and solvent extraction, and finally the 241Am was electrodeposited and α-spectrometrically determined using a Si surface barrier detector. The results of the measurements are shown tabulated; they show rather homogeneous distribution in the surface layers of the Mediterranean; the 241Am result was 0.057 +- 0.007 Ci/litre. Results were also obtained for Pu isotopes. The Am/Pu ratio was found to be in reasonable agreement with that obtained for Lake Michigan water. (U.K.)