386 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



activity received by those who eat only terrestrial foods, which is, of 

 course, not considered a dangerous amount. 



Although V. T. Bowen stated in 1961 that the ocean-water column 

 contains about three times more strontium 90 per unit area than does 

 the land surface at comparable latitudes, this quantity of material 

 diluted in water to depths of more than 1,000 meters is of far less con- 

 cern to man than a much smaller amount of strontium 90 in the first 

 few centimeters of soil. 



GEOLOGICAL ASPECTS OF SEA DISPOSAL 



In the disposal of wastes at sea, several of the important consid- 

 erations are geological. Sediments accumulate in coastal slopes and 

 they may shift down the slope by sliding or slumping. On occasions 

 when water becomes mixed with mud, a mudslide can form and move 

 as a turbidity current onto an adjacent, more level sea bottom, thereby 

 smoothing the original topography to form abyssal plains. Sediment 

 slides of considerable magnitude occur on the continental slopes at 

 unpredictable intervals. A waste container caught in such a slide 

 could be broken or rolled along with it. Ciiistal fracture zones, or 

 areas where the bottom sediments maj'^ be subjected to unusual stresses 

 from tides, waves, storm surges, and tsunamis, result m mipredictable 

 effects on waste containers. 



Coastal waters often contain relatively large amounts of suspended 

 solids. The suspended material usually includes some living orga- 

 nisms, and substantially larger quantities of organic and inorganic 

 particles of detritus. The ability of these solids to adsorb radioactive 

 materials is variable, depending on the mineral composition of the 

 solids, the composition of the water, and the past history of the solids. 

 Although prediction values cannot be given accurately for such ad- 

 sorption, solids are believed to play a major role in controlling the 

 dispersal of liquid radioactive wastes, as well as of those that may 

 escape from a waste package. A relatively large accumulation of 

 radioactive substances is laiown to occur on the sediments in the area 

 around the outfall of the British Atomic Energy Authority processing 

 plant at Windscale, on the Irish Sea. 



Sedimentation, if its occurs at large distances from shore outside of 

 bottom-fishing areas, can be considered a favorable process in removal 

 of radioactive wastes from the environment of man. Since it is a 

 concentrating process, however, it can enter into one of the routes 

 of radioactivity from the sea to man through contamination of fish 

 products, edible seaweed, fishing gear, and beaches. 



Sedimentation is the ultimate step in the transfer of materials from 

 sea water to the sea floor, and a number of physical-chemical processes 

 determine the degree. These processes include the physical-chemical 



