Pollution 



303 



area of Chart I. Probably most of the 

 longer-lived fine-grained fallout debris that 

 is not dissolved becomes concentrated at the 

 floors of the basins with the clays and silts 

 normally deposited in these areas. 



Many radioactive waste products have 

 been intentionally introduced on the as- 

 sumption that the ocean is a convenient and 

 limitless receptacle for atomic garbage. Two 

 plans have been followed, containment and 

 dilution. Material disposed by containment 

 is packed in 55-gallon or smaller steel drums, 

 mixed and weighted with concrete, and sunk 

 in deep water. Atomic Energy Commission 

 wastes so disposed in the Atlantic consist of 

 material irradiated by reactors, liquids soUdi- 

 fied by mixing with cement or gels, contami- 

 nated solids, and combustible solids (Carritt, 

 et al., 1958). The officially designated dump- 

 ing area for southern California is Santa 

 Cruz Basin in depths greater than 2000 

 meters, and for northern California it is the 

 continental slope off" San Francisco at more 

 than 2000 meters. According to Faughn, et 

 al. (1957), between 1946 and 1956 the San 

 Francisco area received 10,000 packages 

 totaUng about 10,000 curies (probably mostly 

 from reactors), and the southern California 

 area received at least 825 drums containing 

 about 40 curies, mostly of the sort discarded 

 by smaller research laboratories. 



Ordinary steel drums are not very strong 

 and, unless all the air spaces of their wastes 

 are displaced by concrete, some of the drums 

 can be damaged or ruptured during descent. 

 Rusting at the bottom within probably less 

 than 10 years releases some of or all the 

 material, as does leaching of concrete in 

 time. Nevertheless, even the temporary 

 holding in containers permits reduction of 

 radioactivity, particularly of short-lived iso- 

 topes; slow leakage from the containers also 

 reduces peak concentrations in the water. 

 Once released, the waste products become 

 diluted by diffusion and currents in much the 

 same way as would low-level wastes intro- 

 duced directly into the ocean, the second 

 mode of disposal. This mode has not been 

 used in southern California, except for acci- 

 dental and intentional disposal of radioactive 

 wastes from laboratories and hospitals into 



public sewage systems in quantities that are 

 estimated to total about 4 curies per year of 

 gamma radiation at the Hyperion Sewage 

 Treatment Plant (W. A. Schneider, personal 

 communication) and consist mostly of short- 

 lived isotopes of iodine and phosphorus. 

 However, according to Carritt et al. (1958), 

 one British nuclear power plant has been 

 authorized to dump 10,000 curies per month 

 into the Irish Sea through a 5-km pipeline. 

 Maps show that nine existing and proposed 

 British plants are located along the coast 

 (Hinton, 1958) in such a way that probably 

 all intend disposal at sea of low-level waste 

 products. Disposal is planned only on a 

 much smaller scale in the United States, 

 where high-level wastes are being held in 

 tanks or pumped underground into presuma- 

 bly tight reservoirs. Doubtlessly, there must 

 eventually be an end to both tankage and 

 underground storage so that disposal at sea 

 of large quantities of even high-level wastes 

 must be considered. Thus we face the major 

 problem of nuclear energy, for which the 

 equilibrium level of waste products has been 

 estimated at 3 x 10" curies by the year 2000. 

 Once the radioactive wastes are mixed 

 with sea water, their concentrations are re- 

 duced by natural decay, dilution, adsorption 

 on sediment particles, and uptake by organ- 

 isms. Two of the most common radioiso- 

 topes shipped by the Atomic Energy Com- 

 mission, iodine 131 and phosphorus 32, have 

 half-lives of only a few days, so they soon 

 become unimportant as compared with other 

 elements. Most important is strontium 90, 

 followed by copper 64, cesium 137, and iron 

 59 (Carritt et al., 1958). Dilution is the next 

 most important factor and it occurs by dif- 

 fusion and currents. The main point of 

 interest here is that the currents must not 

 sweep unfavorable concentrations into rec- 

 reational areas along the shore. Adsorption 

 of radioactive materials on suspended and 

 bottom sediment particles should withdraw 

 some of them from availability to sea water, 

 but in areas of disposal, such as the floors of 

 basins, the bottom is not greatly disturbed 

 by currents so there is little suspended sedi- 

 ment, and the shallow shelves with their high 

 turbidity due to suspended sediment are not 



