RADIOACTIVE ELEMENTS AND DEEP-SEA SEDIMENTS 



379 



■^^ 

 x: 

 I- 15 



"^o 10- 

 5 



10 



20 



30 



AO 



50 



50 cm 



Core 83 



Fig. 5. Measurements on radioactive nuclides from Pacific clay core 83 of the 

 Swedish deep-sea expedition, 1947-1948. Graph shows activities of the following 

 nuclides plotted against depth in core: radium (KroU, 1955); uranium (Hahofer 

 and Hecht, 1954); ionium (Picciotto and Poulaert, unpublished). At top is shown 

 the thorium content of selected layers in the core (Picciotto and Wilgain, 1954). 



first time, in Brussels by methods whicli had been specially 

 developed for this problem (Isaac and Picciotto, 1953; Picciotto 

 and Wilgain, 1954; Hirschberg, 1954). Figures 4-6 show typical 

 results. 



A similar series of measurements has since been carried out in 

 the U.S.S.R. by Baranov and Kuzmina (1958) on sediments of 

 the northwest Pacific and of the Antarctic sector of the Indian 

 Ocean. 



All these results are still very dispersed, and a far greater 

 number of measurements and observations are necessary in order 



