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of its biological persistence. The addition of lead to gasoline is being 
reduced, and its use in paints is being discontinued. The recognition 
and discontinued or restricted use of other hazardous substances will 
further help abate ocean pollution. 
Prevention of Accidental Pollution 
Technology is also advancing in the area of pollution prevention 
from accidental causes. Significant improvements in offshore drilling 
technology and blowout prevention have been made since the Santa 
Barbara blowout in 1969. Drilling in the stormy weather of the North 
Sea has presented a challenge that technology has, in general, been able 
to meet. While there have been losses of drilling rigs, these have been 
reduced with equipment improvements and pollution has been mini- 
mal. Development of offshore single bouy mooring systems may help. 
prevent tanker groundings and reduce the possibilities of a major 
spill. 
Pollution Control and Containment 
For most of the specific marine pollutants mentioned in this report,. 
there are currently no means of removal once they have been intro- 
duced into the marine environment. For example, it would be highly 
impractical to attempt to remove chlorinated hydrocarbons when they 
are present in low concentrations even if a physical or chemical method 
were available. Even a spill of these materials producing a locally high 
concentration would be essentially impossible to recover or contain, 
and dispersion would be rapid. Heavy metals in solution present much 
the same problem and currently are not recoverable when dispersed 
in low concentrations in the marine environment. Concentrations 
would have to be much higher than are necessary to produce harmful 
toxic effects on the marine ecosystem before recovery of the metal 
ions would be possible. 
Petroleum is one of the few marine pollutants that is possible to 
contain or control in part if action is taken promptly after the spill 
occurs. This is mainly because oil floats and does not become imme- 
diately dispersed into the marine environment. Since oil spills are a 
fairly frequent occurrence, occasionly are of very large size, and 
represent a real threat to coastal areas, extensive research has gone 
into oil spill control. Most of the research has involved combating oil 
spills by variations on one or more of the following basic techniques: 
(1) mechanical containment—booms and air-bubble barriers are 
generally less useful in rough seas or the open ocean although a major 
research effort by the U.S. Coast Guard has resulted in an open ocean. 
barrier system capable of being easily transported by air and dropped 
where needed within four hours after notification of a spill incident. 
The system is designed to be effective in 5-foot seas, 20 mile per hour 
winds, and currents‘up to 1 knot and can survive 10-foot seas with 
40 mile per hour winds. 
(2) physical sinking methods—sinking agents have been developed 
and were used with some success in the Torrey Canyon disaster; how- 
ever the effect of sunken oil on the ecology of benthic communities on 
the ocean floor appears to be deleterious although it is not well under- 
stood. 
