392 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



density gradients, the direction of principal dispersion, and the volume 

 of the containing water. Predictions of the rates of dispersal of 

 wastes from any type of introduction are very difficult. Such esti- 

 mates await the data from experimental releases of dyes or radioactive 

 materials. 



Turbulent diffusion results from the state of motion and the exist- 

 ence of gradients in the ocean. The warm surface layers are separated 

 from the cold bottom layers by an area that exhibits rapid temperature 

 decreases with depth. The intermediate layer may extend to about 

 1,000 meters in depth, with waters below that gradually decreasing 

 in temperature. Changes in salinity and density accompany the 

 changes in temperature and provide a base on which diffusion operates 

 with various pressures from gravity, tides, storms, and other forces. 



The averaging of the effects of turbulent diffusion in computations 

 of waste disposal have been relatively unsuccessful. Thus, the recent 

 development of techniques to measure diffusion rates experimentally 

 has been noted with great interest. In one case the fluorescent dye, 

 rhodamine B, serves to make large-scale tracer studies in the open 

 ocean feasible scientifically and economically. Such experiments help 

 to predict the effect of an accident to a seagoing reactor, or of delib- 

 erate disposal of an operating nuclear space vehicle (pi. 2, fig. 2). 



In the Eastern Pacific and at various other places, the oceans exhibit 

 areas of upwelling. Within these areas, often many square miles in 

 size, colder water is transported from the deep oceans to the surface. 

 Care must be exercised in the location of waste-disposal sites to avoid 

 the sea bottom where upwelling occurs. 



Consideration has been given to the location of waste disposal sites 

 in areas where relatively isolated water occurs beyond sills that ap- 

 proach the surface of the ocean. 



Others have suggested the use of deep trenches, although reasonably 

 strong currents, in the order of centimeters per second, may be noted 

 near the bottom of certain deep trenches. The most recent National 

 Academy of Sciences report of waste disposal recommends that such 

 trenches not be used. 



MARINE ECOLOGICAL ASPECTS 



The biological oceanographer is concerned with the disposal of 

 radioactive wastes at sea from five standpoints : the role of organisms 

 in increasing or decreasing the vertical and horizontal transport of 

 radionuclides, the ability of organisms to concentrate radioactive ma- 

 terials, the interaction of radioactive materials with the biota, the 

 biological effects of radiation on organisms, and the utilization of 

 added materials to trace biological processes and to study productivity 

 of marine waters. 



