of the walls. The effective diffusion coefficient through the walls is 
taken as the molecular diffusivity times the porosity of the walls, and 
in numerical computations is assumed to be 10°cm2/sec. The relative 
concentration-distance relationship is shown by curve 3 in figure 4. 
Reid further shows that under the condition of continual supply of 
canisters to a disposal area and given the assumptions noted above, the 
time required to reach a steady state between rate of disposal and leach- 
ing rate will be fourteen years. That is, only after fourteen years will 
the quantity of contaminant released to the water be equal to the rate at 
which contaminant is deposited on the bottom in canisters. If the life of 
the steel canister is ten years, as noted previously, the time to reach 
steady state would then be an additional ten years, or a total of twenty- 
four years. 
SORPTION AND EXCHANGE 
Coastal waters in general contain relatively large quantities of 
suspended solids. The solids are in part living organic materials, the 
plankton, and in part suspended, inanimate, organic and inorganic solids. 
A portion of the latter are materials being carried seaward by land 
drainage sources and will ultimately become bottom deposits. Another 
portion, that usually near the ocean bottom, is periodically brought into 
suspension by tidal action and storm-generated turbulence. All these 
materials including the "bottom" have a measurable:tendency to adsorb 
(remove from solution) and to hold substances dissolved in the water. 
The sorptive properties of these solids are extremely variable. 
Neglecting for the moment uptake by marine organisms, the quantity of 
material adsorbed by a given weight of suspended inorganic solids will 
depend upon the mineral composition of the solids, the composition of 
the solution in which the solids are suspended, and the past history of 
the solids. All of these factors are nearly impossible to evaluate quan- 
titatively for conditions likely to be found in nature. 
Although impossible to evaluate quantitatively, it seems certain 
that sorption processes will play a major role in controlling the dis- 
persal of radioactive wastes once they are free of the canister. This 
conclusion is based upon the results of a few laboratory studies, in ad- 
dition to qualitative field observations made during bomb tests and by 
the British at their disposal operation in the Irish Sea. The details are 
given in NAS-NRC publication 551, chapter 6 (5), and are summarized 
below: 
1. Partial removal of mixed fission products from solution was 
achieved by centrifugal separation of naturally occurring solids from a 
contaminated solution. 
2. The sorption of phosphate, iodide, iron III, strontium, sulphate, 
and copper II onto Chesapeake Bay sediments has been measured under 
a variety of environmental conditions. With the exception of iodide, ap- 
preciable removal from solution by the solids was observed under all 
conditions, 
24 
