VI 



Nuclear energy. — Nuclear testing in the upper atmosphere, and the 

 reprocessing of fuel from nuclear reactors are two significant contribu- 

 tors of radioactive pollution to the oceans. 



MAEINE POLLUTANTS OF GREATEST CONCERN 



Pollutant characteristics. — According to Dr. Bostwick Ketchum, of 

 Woods Hole Oceanographic Institution, there are three characteristics 

 of each and every pollutant which must be taken into account before 

 an evaluation can be made as to the possible impact on or hazard to 

 the environment. These are: (a) The total quantities produced, and 

 thus the amount which might be expected to reach the environment; 

 (b) the toxicity of the pollutant to marine organisms, and to man if 

 it reaches him through seafood; (c) the degree of persistence of the 

 pollutant in the environment. 



Major classes of foUiitants. — The ocean pollutants of greatest global 

 concern may be classified as heavy minerals, synthetic organic chem- 

 icals, petroleum, domestic wastes, and solid wastes. 



Heavy 7ninerals. — Toxic at low concentrations, and nonbiodegrad- 

 able, the heavy minerals reach the marine environment as a result of 

 weathering and their ultimate transport by rivers to the sea. ^lany are 

 also present in coal and petroleum and are released in varying amounts 

 to the atmosphere by combustion. Although some of the heavy min- 

 erals may be complexed and retained in bottom sediments, once added 

 to the marine environments, they remain there permanently. 



Synthetic organic chemicals. — A wide varietj'^ of synthetic organic 

 chemicals is also reaching the environment including detergents, phar- 

 maceuticals, and particularly the chlorinated hydrocarbons as DDT, 

 and polychlorinated biphenyls (PCB's). Having been produced in 

 large quantities, and now found even in the water and organisms of 

 the open ocean, these compounds are not readily biodegradable and 

 thus are extremely persistent in the marine enviromnent. 



Petroleum. — Oil pollution is an increasing threat because of our 

 growing demands for energy and the increased transport of oil by 

 oceangoing very large crude carriers (VLCC's). Crude oil, refined 

 products, and petrochemicals are currently polluting the sea in large 

 amounts. Sources include accidental spills, tanker operations, other 

 vessel operations, offshore production, industrial and refinery oper- 

 ations, and automotive wastes. 



Domestic ivastes. — Domestic pollution consists of the natural prod- 

 ucts of human metabolism which are readily biodegradable and there- 

 fore are not persistent in the environment, save added fertilizing ele- 

 ments. Problems result, however, when the treated discharge exceeds 

 the receiving capacity of the body of water to Avhich it is aclcled. Also, 

 many sewage effluents contain toxic materials from industrial addi- 

 tions and urban runoff. Stepped-up treatment methods can remove 

 most of these f i-om the effluent, but they will still remain in the sludge 

 which also must be disposed of in some manner. 



Solid wastes. — The disposal of solid Avastes poses increasing prob- 

 lem. Even though much is nontoxic, large quantities are involved. 

 Solid waste materials dumped in the coastal waters of the United 

 States comprise, among others, dredge spoils, industrial wastes, sew- 

 age sludge, construction and demolition debris, and explosives. 



