(see Methods) were designed to test the adsorption of cesium and strontium 

 onto the cell wall. The exposure times for cesium varied from 3.5 minutes 

 to 178.5 minutes and the intervals of 2, 4, 10, 20, 40, 80 and 160 minutes 

 were used with strontium-89 . 



The results from the cesium experiment revealed that neither G. simplex 

 nor K. rotundata removed cesium from the medium up to 178.5 minutes. The 

 adsorption of Sr-89 by G. s imp lex would seem to play no part in the uptake 

 of strontium by this organism. The only indication of any uptake occurred 

 in exposure times of 80, 160 and 160 minutes. And even then there was less 

 than 47o difference in the counts. While K. rotundata in prior experiments 

 showed a remarkable ability to concentrate strontium, there was no uptake by 

 adsorption. The results of these two experiments are shown in tables 9 and 

 10. 



7 . The Culture of Phytoplankton in Defined Medium 



Since it is impossible to control the various ion concentrations in 

 a culture medium when natural sea water is used, an extensive investigation 

 into defined culture media was made. In addition to a literature search 

 into the various synthetic media which had been successfully used for the 

 culture of phytoplankton, the following authorities were personally contacted: 

 Bruce Parker of the University of Southern California, John McLaughlin from 

 Haskins Laboratory, Michael Bemhard from La Spezia and Carl Oppenheimer of 

 our own Laboratory. Early success in growth of unialgal cultures of Amphidinium 

 sp . (operculatum) and Katodimum sp . rotundata was achieved with Haskins 

 Laboratory medium formula ASP82. However, this did not provide growth for 

 G. simplex . Guillards synthetic medium was tried also for G. simplex without 

 success. Neither of the above media supported growth as well natural sea 

 water media. This was thought to be due to the low concentrations of potassium 



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