media by centrifuging the media at 1500 rpm for 5 minutes. Then a one-ml 

 aliquot was removed from the supernatant liquid and placed in a planchet. 

 To insure consistency, the one-ml samples were diluted with distilled water 

 until it covered the entire surface of the planchet, then it was dried under 

 IR light and stored in a desiccator until it was counted. After sampling, 

 the supernatant was decanted and the cells resuspended in fresh media. The 

 cells were removed from this media in the same manner and the medium was again 

 sampled. The cells were then resuspended in fresh medium and filtered onto 

 tared Millipore filter discs, dried and stored In a desiccator until counted. 

 The purpose in washing the cells was to compare the activity remaining on the 

 cells after this procedure with the loss of isotope from the medium in the 

 first sample „ In this way an evaluation of prior data could be made. 



All tests were made in duplicate and all samples were drawn in duplicate. 

 The amount of isotope adsorbed by the algae was determined by comparing the 

 amount of radionuclide remaining in the medium after the initial centrifugation 

 with the control which set up using sterile medium and no cells. 



To check the experimental error due to the sampling techniques, duplicate 

 controls were set up. From each of these four one-ml samples were removed and.' 

 handled in the same manner as described above. The highest percent deviation* 

 observed for either of the positive controls was 6.77o. The calculated percent 

 deviation between the averages of the two controls was less than one percent. 

 The calculated percent deviation of the average of all eight samples was 4.57„. 

 The value of 4.57o was used as the experimental error and values falling within 

 the range of plus or minus 4.5% of the control were considered as equal to the 

 control. The values in the analysis of the data are the average? of the 

 duplicates run on each test exposure time. 



One additional factor which was investigated was the amount of time 



* 7o deviation is calculated as the standard deviation di^'ided by the mean 

 times 100... 



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