Plutonium contents in marine environmental samples

This paper contains the results of the analysis of plutonium contents in the sea water near the nuclear facilities and the sediment of offshore Tokai. The results are compared with the concentration of plutonium in the sediments of other regions in Japan. The procedure for the analysis of plutonium in sediment and sea water is explained schematically. The sampling was made at 18 stations of offshore Tokai. The plutonium content in the sediment of offshore Tokai ranged from 4 to 41 pCi/kg-dry, and that in other regions from 5.1 to 130 pCi/kg-dry. The concentration of plutonium in coastal water of Tokai-mura and its vicinity is shown in a table, and it ranged from 0.5 to 1.2 pCi/1000l. The vertical distribution of plutonium in sediment was also studied. As a result of a series of the monitoring, the fallout plutonium in marine samples is maldistributed locally, even in the restricted area such as the shore Tokai. The concentration of plutonium in the sediment of offshore Tokai was in the range of the local variation among those in other regions in Japan. (Kato, T.)