Williams and Swanson (1958) and Williams (1960) showed that the uptake of 

 cesium- 137 in Euglena and Chlorella was linear with its concentration. 

 Other recent uptake studies include investigations of bacteria by Bernhard 

 (1962), Johnson and Kyker (1961), and Zharova (1961), the uptake and release 

 of cobalt and cesium by soil fungi by Witcamp (1962), a rather extensive 

 coverage of the absorption of radioisotopes by microorganisms by Morgan 

 (1961). 



Related studies being carried on at the Marine Laboratory include the 

 investigation of the uptake, concentration and deposition of Ca, Sr, Y, Cs, 

 Co by marine bacteria, yeasts and fungi. Greenfield (1962) using a Pseudomonas, 

 (B-1) isolated from the shallow waters in South Florida and on the Bahama 

 Banks showed calcium was a growth requirement and that the bacterium could 

 concentrate the cation up to ten times its normal concentration in sea water. 

 When pH was above 7.5 the pseudomonas, precipitates calcium carbonate in the 

 form of aragonite crystals using either a single or clump of bacteria for a 

 nucleus. Meyers has investigated the ability of several marine fungi to 

 concentrate cesium or cobalt at various growth stages. Extremely low con- 

 centration factors were obtained. 



METHODS 



In this study of the uptake of radionuclides by open-sea phytoplankton , 

 four radioisotopes have been used, namely, Sr90-Y90, Y-90, Sr-89 and Cs-137. 

 These isotopes were obtained carrier- free from the Oak Ridge National Laboratory 

 operated by the Union Carbide Nuclear Company at Oak Ridge, Tennessee. The 

 phytoplankton used in these studies were cultures obtained from three tropical 

 open-sea environments: 1. The Florida Current 2. The Tongue of the Ocean 

 area, a deep-water area lying south of New Providence Island, and 3. From 

 the Atlantic Ocean area northeast of New Providence Island. Water samples 



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