Chapter 6 



Precipitation on the Ocean Bottom 



61 



Nevertheless, for an understanding of the 

 overall process — so that predictions for condi- 

 tions other than those existing at the time of 

 observations can be made, and to provide infor- 

 mation useful to other studies, many individual 

 processes should be studied. The following 

 studies, grouped according to the primary source 

 of information, and thought to be pertinent to 

 the sedimentation and retention problem, would 

 provide some insight into these processes. Ob- 

 viously, information obtained from one group 

 of studies may be of value in the solution of 

 problems in others. 



Data from weapons tests 



1. Measurement of the immediate partition of 

 weapons test debris among large-sized immedi- 

 ate fallout, water-borne activity and the air- 

 borne material which may be quite uniformly 

 distributed over the world. 



2. Measurement of partition of individual iso- 

 topes in sea water between particulate material 

 and solution. (Dynamic and equilibrium con- 

 ditions). 



3. Mechanism of sorption of radioisotopes on 

 natural suspended solids under the conditions 

 existing in ocean water. 



4. Measurement of settling rates of natural in- 

 organic particulates, probably by tracer tech- 

 niques. 



5. Measurement of detrital settling rates, in- 

 cluding plankton average life. 



6. Measurement of uptake and element differ- 

 entiation in organisms which may become de- 

 trital material. 



Data from waste disposal experiments 



Certain studies here can be combined with 

 tracer studies, designed primarily to give infor- 

 mation on basic oceanographic problems: 



1. Life expectancy of burial containers. 



2. Diffusion rate from concreted or sintered 

 blocks as a function of size, and the concentra- 

 tion and istopic composition of wastes. 



3. Regardless of what disposal system is 

 adopted, there will be liquid wastes produced, 

 and studies must be made of liquid waste dis- 

 persal. The pertinent effects will be more re- 

 lated to the weapons test data requirements 

 since this is a surface to bottom transfer. 



Tracer experiment data 



1 . Coprecipitation of individual fission products 

 with their stable isotopes normally occurring in 

 sea water, and the particle size distribution of 

 the solids formed, and their sedimentation rate. 



2. Similar data on coprecipitation by isomor- 

 phous replacement, for example the carrying of 

 radiostrontium with inactive calcium. 



3. Rate of entry of diffused material into the 

 basic biological systems. This includes the bot- 

 tom to surface movement as modified by sedi- 

 mentation. 



4. Exchange capacities of sediments for the ra- 

 dioisotope ions in sea water medium, and rate 

 of diffusion of these isotopes into the undis- 

 turbed bottoms. 



In all studies in which dispersion, partition, 

 concentration and localization occur, measure- 

 ments that would permit a balance sheet to be 

 made (all the activity should be accountable) 

 seem desirable and necessary. 



SUMMARY 



The only semi-quantitative data relevant to 

 the problem of activity removal from the ocean 

 surface are the geochemical data. These indicate 

 a reduction factor of 14 for strontium, 2,000 

 for cesium, and 100,000 for cerium (and proba- 

 bly all rare-earth-type elements). No informa- 

 tion is available on such elements as ruthenium, 

 rubidium, and iodine. Other mechanisms de- 

 scribed may contribute to activity removal, but 

 their effects cannot be evaluated with present 

 knowledge. 



The reduction factors are for equilibrium con- 

 ditions, and the high sea water activity found a 

 year after the Castle tests (Operation TROLL) 

 indicate that equilibrium is reached slowly. 



Activity introduced on the bottom through 

 sea burial will be subject to entirely different 

 removal processes. No estimate can be made of 

 their effectiveness. 



Carritt, D. E., and S. Goodgal. 1954. Sorp- 

 tion reactions and some ecological impli- 

 cations. Deep-Sea Research 1:224-243. 



Culler, F. L. 1954a. Unpublished results. 



Culler, F. L. 1954b. Notes on Fission Prod- 

 uct Wastes from Proposed Power Reac- 

 tions. ORNL Central File No. 55-4-25. 



