sediment movement versus wave energy. While it is not clear whether such a 

 relationship may be achieved, the addition of data such as described above 

 and other measurements not feasible by normal testing procedures may lead to 

 the development of the desired relationship. 



The techniques by which activated material could be monitored in the 

 laboratory are basically twofold: in situ measurements and laboratory measure- 

 ments of samples taken from the test area. A sampling program is feasible for 

 laboratory studies but such a program becomes enormously expensive if pursued 

 during a field test. Consequently, it is desirable to design laboratory studies 

 which utilize in-place measurements extensively and to supplement these measure- 

 ments with a sampling program. The design of field applications would of course 

 minimize the use of sampling. In this fashion it will be possible to gain valu- 

 able experience from laboratory studies which may be applied to field techniques 

 when working in a littoral environment,. 



The physical detection of the emitted quanta is a typical gamma photon 

 detection system which includes a stable high voltage supply, detector, linear 

 amplifier, pulse height analyzer, and scaler. A 2 x 2-inch sodium iodide, 

 thallium activated crystal and a photo-multiplier tube are the heart of the 

 detector. A detector developed at the University of California for the San 

 Francisco District of the Corps of Engineers will be utilized in the first 

 studies. The remaining components are available commercially. 



One factor of critical importance in any test which uses radioisotopes as 

 tracer materials is the selection of the vehicle to carry the activated material. 

 The most obvious and most important criterion is that this vehicle must behave 

 in exactly the same manner as do the natural sediments. The other equally ob- 

 vious and important criterion is that no hazard should result from the use of 

 any vehicle or carrier. It is apparent therefore that the optimum carrier 

 would be the natural sediments, provided that a representative size distribution 

 of the sediment was obtained for irradiation. There are problems, however, 

 associated with this technique. Goldberg and Inman (see bibliography) attempted 

 this technique and were in fact able to irradiate the local sediments and de- 

 tect irradiated particles. Neither the silicon nor the oxygen of the normal 

 quartz sand were detected however, as both these isotopes have unusably short 

 half lives. The radioisotope which was detected was phosphorous (P 32 ) which 

 was present as an impurity in the sedimentary grains. Inasmuch as phosphorous 

 is a beta emitter, and beta particles are attenuated rapidly an extensive 

 sampling program was necessary. Several techniques have been suggested by 

 which the natural sediment will sorb the radioisotope. Gibert has precipitated 

 silver (AgHO) on natural sand grains. Eakins and Smith suggested etching 

 natural sand before sorption was attempted and Krone has sorbed gold (Au 198 ) 

 on the muds and silts of San Francisco Bay. Gibert's technique requires ex- 

 tensive sampling and extensive laboratory procedures. The particles suggested 

 by Eakins and Smith may sorb the irradiated material differentially and thus 

 not be representative of the natural sediments, and the muds and silts of Krone 

 are not usually the predominant material found in the littoral zone. All of 

 the methods mentioned above, as a consequence, appear to have severe limita- 

 tions. 



Another approach has been the utilization of an artificial carrier which 

 simulates the natural sediments. Glass has been the material most popular in 

 the past. Inose, Kato, Sato and Shiraishi used glass in Japan; Putman and Smith; 



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