OCEANOGRAPHY IN THE UNITED STATES 331 



Mr. Miller. Will you define "chelate" for us, please ? 



Dr. Seymour. Chelation is a chemical process whereby one com- 

 pound will grasp and hold onto another clieniical element. In marine 

 biology we call the pincers of a crab "chele," which means to grab 

 and hold onto. 



It has been found that certain natural compounds which are formed 

 in the deep sea will chelate thorium and other radiochemicals. Studies 

 of chelation shed light on the permanency of storage and future avail- 

 ability of radioactivity. 



What Dr. Wallen has in mind here is that some of the sediments on 

 the bottom can grasp and hold onto chemical elements, and that if this 

 element should happen to be radioisotope, they could hold radio- 

 activity. For instance, clay materials have this characteristic and is 

 a factor to be considered in the distribution of radioisotopes. That 

 is, the clay or other sediments may remove radioisotopes from the 

 water and hold them on the bottom. However, once they are on the 

 bottom, they can become available to what we call detritus feeding 

 organisms, organisims which scoop up mud and filter it. They actually 

 eat mud and remove some organics from the mud. It this way, also, 

 they remove radioisotopes. 



Mr. Miller. They in turn enter into the general cycle of some other 

 type eating them ? 



Dr. Seymour. Yes. 



Mr. Miller. On up the scale until it gets to man. 



Dr. Seymour. Yes. This is what we refer to as the food web. It 

 makes little difference how the organism acquires the radioisotope, 

 whether it is adsorbed on the outside surface of the organism or 

 whether it is actually absorbed within the tissues. The organism that 

 feeds upon it has access to it, and in this way the radioactivity can 

 move through the food web. 



However, I think it should be kept in mind that just because a radio- 

 isotope is concentrated by one organism, it is not necessarily going to 

 be concentrated by the organism higher in the food web that feeds 

 upon it. Concentration is dependent upon the physiological need of 

 the organism for the element. 



Mr. Miller. Do you knoAv what effect this would have on the life 

 cycle ? 



Dr. Seymour. No, we have no direct evidence as to what the effect 

 is. 



Mr. Miller. There may be mutations as a result of them ? 



Dr. Seymour. This is a possibility, but we have no direct evidence 

 of this occurring. In our studies in the Pacific at Eniwetok-Bikini 

 test site where the levels of radioactivity are, of course, extremely high 

 compared to other parts of the world, we have looked but we have not 

 positively been able to identify any mutations resulting from con- 

 tamination by radioactive isotopes. 



Mr. Miller, Under controlled conditions with marine organisms, 

 could you find such evidence ? 



Dr. Seymour. Genetic studies have not been undertaken to study 

 tlie effects of radioisotopes on marine organisms. 



Mr. Miller. AVould that be desirable ? 



Dr. Seymour. Yes, it would be desirable. 



S&ITO— 59-^22 



