WASTES IN THE SEA — ^WALLEN 385 



time the radioactivity was so diluted that, for practical purposes, the 

 pool ceased to exist. A second such experiment was a part of the 

 1962 Dominic Nuclear test series, and the results, when available, 

 should add substantially to an understanding of dispersion in the 

 open ocean. 



For such tests in the ocean it is not a question of "clean" (fusion) 

 devices and "dirty" (fission) devices, since the induced radioactive 

 isotopes (zinc 65, iron 55, 59; manganese 54; and cobalt 57, 58, 60) 

 in the vicinity of any reacting nuclear device appear to be more im- 

 portant to marine organisms than fission products (strontium 90 and 

 cesium 137). 



Seagoing reactors, such as nuclear submarines, may store certain 

 wastes for later disposal on land but under many circumstances the 

 hazard to humans is less in oceanic disposal than when such wastes 

 are kept in proximity to ship's personnel. Since avoidance of detec- 

 tion is a goal in nuclear military ship movements, care is taken to 

 insure that detection of the vessel not be possible by identification of 

 its wastes. 



NATURAL RADIOACTIVITY 



Not all of the radioactivity in the ocean originates from the nuclear 

 industry. Naturally radioactive materials are present in the earth's 

 crust; and these materials may arrive in the oceans by way of dust, 

 ground water, and rivers. Over geological times the quantity of radio- 

 active isotopes from continental sources in the ocean and in sediments 

 is believed to have become relatively constant and to be distributed 

 evenly throughout the seas. 



As cosmic rays pass into the atmosphere they strike atoms of stable 

 elements, and a small portion becomes radioactive. These cosmic 

 ray-produced isotopes, such as carbon 14, hydrogen 3 (tritium), and 

 sodium 22, are often short lived as compared to ocean turnover times, 

 so that they may occur in surface waters ; but they never become evenly 

 distributed in the ocean. The concentration of these isotopes in oceanic 

 layers is used to indicate the circulation of the sea over a short period 

 of time. 



In the book Radioactivity in OceanograpJiy^ F. F. Koczy and J. N. 

 Kosholt have computed the concentration of more than 70 radioactive 

 isotopes in the ocean from primordial, cosmic ray, and artificial 

 sources. Research to refine these values will assist in evaluating the 

 distribution and effects of waste disposal on the ocean. Various pop- 

 ulation groups may be exposed to radiation from land sources as great 

 as 16 times that of other human groups. Such diflferences are related 

 to the characteristics of the soil upon which the population lives and 

 the type of material used in housing. Persons who eat mostly seafood 

 may receive only about one one-thousandth of the exposure to radio- 



