Normal or 



Operational 



Inputs 



Non-Tankers 



How Does Oil Get 

 into the Oceans? 



It is estimated that more than 

 1 .5 million metric tons* of oil or 

 petroleum products enter United States 

 coastal waters each year. The bulk of 

 these inputs result from human activi- 

 ties, mostly from urban and river runoff 

 (42%), and normal tanker operations 

 which include cleaning tanks and 

 ballasting (14%). Although less than 

 3% of the oil enters coastal waters 

 because of tanker and offshore produc- 

 tion accidents, such oil spills are impor- 

 tant because they create higher con- 

 centrations of oil than do most other 

 sources of oil pollution, and, therefore, 

 pose a special kind of environmental 

 threat. 



An oil spill can happen whenever oil 

 is transported, stored, handled or ex- 

 tracted from the earth. About 10,000 

 oil spills totalling 10 to 20 million 

 gallons of oil can be expected in or 

 near the territorial waters of the United 

 States every year. However, the annual 

 amounts of spillage are variable and 

 dependent on the frequency of major 

 oil spill disasters. A single accident in- 

 volving a supertanker could spill more 

 oil than the total annual spillage into all 

 U.S. waters. The Amoco Cadiz, for ex- 

 ample, lost over 60 million gallons of oil 

 when it broke up off the coast of 

 France in March of 1978. In U.S. 

 waters, spilled oil is more frequently a 

 problem in the Atlantic Ocean and the 

 Gulf of Mexico than in the Pacific 

 Ocean. A large portion of the spilled oil 

 enters near-shore areas where winds 

 and currents may transport the oil to 

 pollution sensitive river outlets and bay 

 areas (estuaries), tidal flats and 

 marshes. 



*One metric ton equals about 7 barrels. 

 One barrel equals 42 U. S. gallons. 



Source: National Academy of Sciences, 1974. Petroleum in the marine environment: Inputs, 



techniques for analysis, fates and effects. Ocean Affairs Board, NAS, Washington, D.C. 



Although less than 3% of all oil entering the marine environment results from tanker and off- 

 shore production accidents, oil spills are unique because they create high concentrations of oil 

 in the environment, and therefore pose a special kind of environmental threat. 



