Despite a massive cleanup effort, experts warn that only a tiny fraction of the oil spewing into the Gulf of Mexico from the wreckage of a BP-leased rig will ever be recovered.

 

"The oil is out there and it's out there to stay," said Lisa Suatoni, a marine biologist with the Natural Resources Defense Council. "There's a dismal record of cleanup associated with oil spills. Generally less than 1 percent of spilled oil is ever cleaned up."

 

Even in the case of the 1989 Exxon Valdez spill — when billions were spent in a years-long effort to sop up the oil from a rocky and sandy shore and skim it off the relatively calm waters of Prince William Sound — only about 7 to 10 percent of the oil was actually recovered, Suatoni said.

 

While a significant percentage of the Valdez oil was dispersed by natural processes, the shoreline is still littered with pockets of oil which sank into low-oxygen areas where its toxicity was preserved.

 

Which means every time an animal burrows in the wrong place or a big storm shifts things around on the beach, more oil can bubble up.

 

The very nature of the Gulf of Mexico spill makes significant recovery impossible, said Tony Wood, director of the National Spill Control School at Texas A&M University Corpus Christi.

 

The oil has been gushing up from a ruptured pipe 5,000 feet (1,500 meters) below sea level and 52 miles (84 kilometers) from the coast of Louisiana since April 22.

 

By the time it reaches the surface, it has already begun to break down into smaller particles. Rough weather has also broken the massive slick up into patches which are spread out across hundreds of miles of open sea.

 

More than 9.7 million gallons of an oil-water mix have been skimmed off the surface and controlled burns have also removed some of the oil from the water.

 

But because the slick threatens fragile coastal wetlands — where recovery is nearly impossible and the environmental impact would be devastating — officials approved the use of chemical dispersants to try to keep as much of the oil away from shore as possible.

 

"If the oil is dispersed then you're not trying to collect it, you're trying to disperse it into small enough particles that bacteria can attack it," Wood said.

 

"Of course the toxic fractions are still there from the oil and the dispersants."

 

The Environmental Protection Agency (EPA) has repeatedly said that while dispersants come at an environmental cost, they are nonetheless less damaging than allowing the oil to reach shore in chunky, thick globs that can choke both wildlife and vegetation.

 

But environmentalists, scientists and fisherman have raised concerns that the dispersants could be creating a toxic soup in critical habitats and simply shifting the damage from the oil out of sight.

 

Another problem is that a month into the disaster, nobody really knows how much oil is actually out there.

 

BP and the federal agencies overlooking the response efforts initially pegged the leak at 1,000 barrels per day, then quickly readjusted the estimate to 5,000 barrels a day after the size of the slick grew exponentially.

 

Independent experts examining video released of the oil gushing out of the ruptured pipe have said the flow appears to be at least 10 times higher.

 

Giant plumes of oil discovered deep underwater also led scientists to question any estimates of the size of the slick that were based only on what could be seen on the surface.

 

"This issue of how much (oil has been released) is really, really critical because natural environments do have an assimilation capacity," said Paul Montagna, a marine ecologist at the Harte Research Institute for Gulf of Mexico Studies.

 

"It'll take a little bit of insult and a little bit of pollution and it literally gets diluted," he said in a telephone interview.

 

"At some point you reach a tipping point and the environment can't handle any more and things go down really quickly."

 

The Gulf is a large body of water and some of the oil has already made its way into the Loop Current, where it will be transported past Florida, Cuba and eventually out into the Atlantic Ocean.

 

But while much of the oil will be diluted, "it's not going to just all disappear" and it will have a significant impact on marine life, Montagna said.

 

"At some point they'll finally get this thing tapped. But the effects of this thing are probably going to take a decade or more to work out."

 

Copyright 2010  AFP Global Edition