RESTRICTED 



20 



Table 9. Calculated inaxli.iur'i concentration of radio- 

 active materials in the surface v/ater after 

 test Balcer {% of initial concentration, 

 radioactive decay not included) 



^ 



analysis cannot be carried beyond this point with any degree of 

 accuracy since both the mathematical theory and the oceanographic 

 factors involved are very complex. Considerable upwelling of 

 bottom water occurs near Bikini island, since this water will 

 have a higher concentration of radioactive material than the 

 surface water, the area between the target and Bikini is more 

 likely to be dangerous than any other part of the lagoon. The 

 maximum concentration in this area probably will not be more 

 than 13.5% of the initial value. This figure is based on verti- 

 cal diffusion alone, since horizontal difinsion is expected to 

 be much reduced in the bottom layer. There is considerable 

 likelihood that upwelling will occur over a broad enough area 

 to dilute the contaminant considerably; however, it is better 

 to be conservative and consider that there may be patches of 

 water v/ith 10% or more of the original concentration of con- 

 tamlnemt . 



At the end of two days most of the bottom water at the 

 eastern end of the lagoon will have upwelled to the surface 

 and will have been diluted by vertical diffusion as it moves 

 westv/ard v/ith the surface current. The rate of diffusion will 

 be 'decreased, since it will be mixing with bottom v/ater that is 

 already slightly contaminated. However, rough estimates indi- 

 cate that none of the water in the target area will contain as 

 much as 1% of the original concentration of contaminant, although 

 higher concentrations may persist near the reef for another day. 



The other end of the strip will have reached the south- 

 western passes at- the end of the second day, and henceforth 

 a small amount of radioactive material will be discharged from 

 the lagoon on each ebb tide. 



