92 



Atomic Radiation and Oceanography and Fisheries 



organisms that had been grown in the effluent, 

 accumulated substantial amounts of P^-. Fish 

 living in the Columbia River downstream from 

 the reactors and which fed on organisms that 

 had assimilated the radioactive materials con- 

 tained over 100,000 times more radiophos- 

 phorus than the surrounding water during the 

 late summer. Krumholz (1954, 1956) at- 

 tributed the high concentrations of Sr^° and 

 Csi37 in the fishes of White Oak Lake to the 

 ingestion of contaminated food organisms. In 

 addition, it was shown that the different kinds 

 of animals which served as food for the fishes 

 accumulated different amounts and kinds of ra- 

 diomaterials. For instance, although a high per- 

 centage of the radioactivity in the food organ- 

 isms, such as larval Chaohorus, emanated from 

 radiophosphorus, only a relatively small portion 

 of the radioactivity in the fish was traceable to 

 that radioelement. Similarly, although only a 

 relatively small amount of radioactivity in the 

 plankton organisms was attributable to Sr^", 

 about 80 per cent of the radioactivity in the fish 

 skeleton emanated from that radioisotope. From 

 these findings it is apparent that the ability of 

 the various organisms in the food web to con- 

 centrate the different radionuclides is of the ut- 

 most importance to the predatory species. If 

 the animals which serve as food were unable to 

 take up the radiomaterials, there would be con- 

 siderably less chance of the predators becoming 

 contaminated. 



The food habits of fishes and other fresh- 

 water organisms determines, to a great extent, 

 which radioelements they may accumulate. In 

 a study of the food habits of the black crappies 

 and the bluegills of White Oak Lake (Krum- 

 holz, 1956) it was found that the diets of those 

 two species were considerably different. Marked 

 differences also occurred in the concentration 

 and relative proportions of the radiomaterials 

 in the tissues of the two kinds of fish. Greater 

 amounts of radiomaterials were concentrated in 

 the soft tissues of the bluegills than in the 

 crappies, and greater amounts of radiomaterials 

 were concentrated in the skeleton and other 

 hard parts of the crappies than in the bluegills. 

 Furthermore, there were relatively greater 

 amounts of radiophosphorus in the bones of 

 the bluegills and relatively greater amounts of 

 radiostrontium in the bones of the crappies. 

 These differences may well have resulted from 

 the dissimilar diets or, perhaps, from diflferent 



physiological demands. Unpublished data of 

 the Hanford Laboratories shows that 50 to 75 

 per cent of the radiophosphorus ingested by fish 

 is assimilated and retained. Unfortunately, 

 there is virtually no other information available 

 on the efficiency of transfer of radioisotopes 

 from food organisms to aquatic predators. 



Concentration of radioactive materials in dif- 

 ferent organisms 



In unpublished results from the studies at 

 White Oak Lake, it was shown that bacteria 

 may have the greatest powers for concentrating 

 radiomaterials of any of the fresh-water organ- 

 isms, their concentration factors for certain iso- 

 topes may exceed 1,000,000. However, it is 

 not definitely known for all radionuclides 

 whether or not they actually enter into the 

 metabolism of the bacteria or are adsorbed to 

 surface areas. Labaw, Mosley, and Wyckoff 

 (1950) showed that the measured radioactivity 

 in Escherichia coli, which had been cultured on 

 a medium that contained P^^ ^^s Na2HP*04), 

 was not due to adsorption of the P^^ on the 

 bacterial surfaces nor to residues from the radio- 

 active culture. 



The data from the Columbia River and White 

 Oak Lake indicate that the phytoplankton usu- 

 ally concentrate greater amounts of radiomateri- 

 als than the zooplankton. Here, again, it is not 

 known for all species whether the radiomateri- 

 als actually enter into the metabolism or are 

 adsorbed to surfaces. Some of the filamentous 

 algae are known to concentrate P^- at least 

 850,000 fold (Krumholz, 1954), whereas for 

 other algae the concentration factor may be as 

 little as 300,000. Some zooplankton have con- 

 centration factors for radiophosphorus of as 

 much as 250,000 but in others it may be less 

 than 100,000. 



Fresh-water invertebrates of all classes studied 

 in the Columbia River and White Oak Lake ex- 

 hibited maximum concentration factors which 

 ranged from less than 100 to more than 100,- 

 000 depending on the radioelement involved. 

 It is believed that most of the radioactive ma- 

 terials accumulated actually enter into the me- 

 tabolism of these invertebrates. Some of the 

 insect larvae concentrate radioelements by fac- 

 tors upwards of 100,000; some of the micro- 

 crustaceans by factors of nearly 200,000; some 

 mollusks may concentrate fission products as ef- 



