235 



1 CHARLES S. YENTSCH 



2 Temperature is only one of these factors. 



3 The light intensity at which the plants are grown also 



4 has the satne sort of effect. The amount of carbon dioxide 



5 present, the amount of phosphate and nitrate also change 

 5 this rate remarkably. Again I emphasize, unless these 



^ factors are carefully screened, it is very difficult to 



g say anything about the maximum rate of photosynthesis. 

 g Consistently the biologists in the Federal 



report found that the 3WL introduction near the outfall 



10 



II was associated with a low value of carbon production, and 



12 



15 

 16 



it is indeed difficult for me to make any judgment why 

 i, these values would be low. I should emphasize that 



j4 biologists have used a rather primitive method of noeasuring 



the rate of carbon production. They have done this by 

 measuring changes in dissolved oxygen. I am startled that 



17 the more modern, precise and accurate method of Carbon 14, 



18 the radioactive Carbon 14, was not utilized. The calcu- 



19 lation of carbon production from oxygen requires a factor, 



20 and this factor can be quite variable and quite dependent 



21 upon the over-all metabolism of the organisms present. 



22 To give you an example, at the point at 



23 which the SWL is introduced, I think everyone will agree 



24 that there is considerable amount of biological oxygen 



25 demand, and in the process of this demand ammonia is 



