General DiscussionWidespread manmade pollution of the sea that can be detected by current spaceborne systems is concentrated in the Middle East, particularly in the Persian Gulf and the Gulf of Oman. Obviously, there is some pollution wherever ships discharge material into the sea that is foreign to the marine environment. These events are short-lived, however, and cannot be located and tracked from space observations (whatever the electromagnetic frequency).
Oil dumps, slicks
The amount of petroleum products ending up in the ocean is estimated at 0.25% of world oil production: about 6 million tons per year. Seagoing tankers carry 60% of all oil extracted. The oceanic pollution is caused when these ships flush their tanks with seawater. A smaller percentage comes from passenger ships and freighters draining water ballast from their fuel tanks (Monin and Krasitskiy, 1985).
The greatest volume of petroleum products dumped into the ocean is carried there by rivers. It represents more than triple the quantity coming from all tankers and other ships. Oil and other petroleum products are discharged into rivers and the ocean by many industrial enterprises, including oil refineries and oil storage installations, The quantity of petroleum products dumped each year into the sewage network by gasoline stations twice exceeds the amount resulting from ship disasters.
Locally, especially in coastal regions, a sudden spill of oil into the sea can have catastrophic consequences that are usually short-lived. In the case of the Kharg Island spill in the Persian Gulf, the flow into the sea has been nearly continuous since 1982. As a result, an entire fishing industry has been destroyed, complete populations of some fish species are now extinct in that habitat, and desalination plants have become inoperative. It is unlikely that the Persian Gulf waters will return to normal in this century.