132 



Atomic Radiation and Oceanography and Fisheries 



counts/sec, therefore the minimum detectable 

 concentration becomes. 



C,= 



2 + 2V1 + O.25/ 

 T^t 



A.U 



gammas/sec/ml which approaches for very 

 large values of t, 



C = 



0.13 



A.12 



Tabulations 



Table 3 compares the effect of increasing the 

 period of measurement with the effect of di- 

 minishing the background. It is evident that a 

 substantial change in background has relatively 

 small practical effect on any measurement made 

 so rapidly that only a very poor sample is taken 

 out of the fluctuating signal; however, when 

 sufficient time can be alloted for good sampling, 

 the background level becomes the limiting fac- 

 tor. It should not be overlooked that in practi- 

 cal field work, instrument imperfections may 

 contribute to the overall error more or less pro- 

 portionally with time of measurement, and that 

 measurement time must be spent economically 

 on almost all oceanographic expeditions. It is 

 apparent therefore that efforts should be made 

 towards increasing the counting rate, ve, while 

 reducing the relative value of the background 

 count by all possible means. Technique for 

 cleanliness and for discrimination of back- 

 ground by electronic means have not yet been 

 fully developed for this purpose. 



REFERENCES 



FoLSOM, Theodore R. 1956. Problems pecul- 

 iar to direct radiological measurements at 



sea. Paper presented at Nat. Acad, of Sci- 

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Glueckoff. 1955. Long term aspects of fis- 

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 Energy, Geneva. Paper No. 398: 11 pp. 



Miyake, Y., Y. Sugiura, and K. Kameda, 

 1954. On the distribution of radioactivity 

 in the sea around Bikini Atoll in June 

 1954. Paper in meteor and geophys., Me- 

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Revelle, R. R., T. R. Folsom, E. D. Gold- 

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RuGGOFF, Milton D. (Editor) Why the sea 

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 676 in Harvest of World Folk Tales. 

 XViii + 734 pages. Viking Press. 



U. S. Atomic Energy Commission and Of- 

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 37 pp. 



U. S. Department of Commerce. 1953. 

 Maximum permissible amounts of radio- 

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