TRANS URANIC ELEMENTS AT BIKINI ATOLL 563 



INLET 



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m/mmmmm/mm/// 



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0.3-pm MILLIPORE FILTER 



FIRST BED 



SECOND BED 



THIRD BED 



FOURTH BED 



OUTLET 



Fig. 14 Schematic representation of the BLVWS showing the flow of water through the 

 filters and sorption beds. 



Water is forced through the BLVWS with an electric pump. The smaller BLVWS 

 requires a lower flow rate than the larger samples; so the flow is controlled by the use of a 

 valve and a water "bypass;" The entire pumping system is shown schematically in Fig. 15. 

 The volume of the water sampled is measured with a recording water meter. 



Collection Efficiencies. Most of the sampling procedures and techniques used in 

 seawater analysis assume 100% efficiency for the collection and measurement or use 

 radioactive tracers to determine the chemical yield of the samples. One problem with the 

 use of tracers is that they are usually not added to the samples in the same chemical form 

 as the element in the sample. If the chemical states of the sample and tracer element are 

 not identical, the isotopic equilibrium might not be reached for a long time, and the 

 chemical yield may be in error. 



Because of the short column lengths used in the BLVWS, collection efficiencies 

 seldom are 100% except for a few elements that are totally retained on the first sorption 

 beds, such as ^"^^Am, ^^^Bi, ^^Fe, and ^^^Eu (Schell, Nevissi, and Huntamer, 1978). 

 Elements that are not collected quantitatively can be determined by the differences in the 

 amounts collected on successive sorption beds, as outlined by Held (1971), Schell, Jokela, 

 and Eagle (1973), and Schell, Nevissi. and Huntamer (1978). 



This method of determining collection efficiencies, referred to as the "BLVWS 

 ichnique," is an empirical method which assumes that a constant fraction of the 



