Natural Sources

forces. A major oil seep, 3600 gal/day, is at Coal Oil Point near Santa Barbara on the coast of southern California. This seep produces an extensive oil slick on the ocean and often results in tar accumulation on the shore. The oil also supports a community of marine microorganisms that metabolize these hydrocarbons. Most seeps produce less than 40 gal/day and the environmental effect appears to be quite limited. The contribution of natural sources to the oil in the marine environment is 9% of all sources.

In 2000, earth-imaging satellites and radar discovered extensive natural seepage of oil into the Gulf of Mexico. It is estimated that the annual amount of oil released per year is twice that of the Exxon Valdez spill (2 x 11 million gallons: Section 6.4.1). This is a gradual release of oil, which wildlife is used to, and it forms a slick on the water 0.01 mm thick, which is of little danger to wildlife and is readily metabolized by bacteria. Some of these seeps have been occurring for thousands of years, and it has been proposed that there are food chains nurtured by the oil released by the seeps.

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