livescience.com

Surprise!

There are natural leaks of oil into the oceans that go on all the time.

This is not to minimize the devastation being wreaked by the Deepwater Horizon blowout. While the environment seems able to deal with natural seepage just fine, thousands of gallons of oil being spewed out in a situation such as the Deepwater Horizon is another matter altogether.

But when you see stories about “oil slicks”, it’s not always a good idea to assume that the oil has come from some evil drilling operation.

The first few paragraphs of the story are quoted below. Read the whole thing to find out how the oceans deal with these natural seepages.

The infamous 1989 Exxon Valdez oil spill, one of the largest in U.S. history, dumped more than 10 million gallons of crude into Prince William Sound.

While the amount of oil and its ultimate fate in such manmade disasters is well known, the effect and size of natural oil seeps on the ocean floor is murkier. A new study finds that the natural petroleum seeps off Santa Barbara, Calif., have leaked out the equivalent of about eight to 80 Exxon Valdez oil spills over hundreds of thousands of years.

These spills create an oil fallout shadow that contaminates the sediments around the seep, with the oil content decreasing farther from the seep.

There is effectively an oil spill every day at Coal Oil Point (COP), the natural seeps off Santa Barbara where 20 to 25 tons of oil have leaked from the seafloor each day for the last several hundred thousand years. The oil from natural seeps and from man-made spills are both formed from the decay of buried fossil remains that are transformed over millions of years through exposure to heat and pressure.