WASHINGTON, June 18 (Xinhua) -- Although it remains unknown when the oil leak in the Gulf of Mexico can be plugged, efforts to clean up the massive BP oil spilled so far could continue until 2011 and well beyond, some experts said.
Rick Steiner, a conservation consultant and former professor at the University of Alaska, said efforts to clear the waters, marshes and beaches of oil could take until next year.
Moreover, there is no guarantee that every trace of the BP spill will be mopped up, as some oil from the 1989 Valdez spill, which took three seasons to get rid of, remains on Alaskan beaches after more than two decades, Steiner noted.
Mark Zappi, dean of the University of Louisiana at Lafayette's College of Engineering, said the length of the cleanup hinges on when the leak is plugged.
A ruptured oil well off Louisiana's coast has gushed an estimated 500,000 to one million gallons (one U.S. gallon equal to 3.785 liters) daily for eight weeks.
A containment cap, installed on June 3, is collecting oil and gas flowing from the offshore well and transporting them to a ship on the surface, according to BP's website, but crude continues to escape. The company began siphoning oil from a second containment system on Wednesday, the site said.
If the leak is plugged within the next month, cleanup efforts could take up to 2012, but pockets of oil could remain for years afterwards, said Zappi, who is involved in the cleanup effort.
The length of cleanup operations also depends on where the bulk of the oil ends up. Crude washing up on sandy beaches with many waves is more biodegradable, whereas the sticky gunk now seeping into marshes is much harder to get rid of, he said.
Tar balls are beginning to wash up on Florida's shore and scientists said the spill could travel further north to the Carolinas.
Scientists and officials said the spill could be the worst environmental disaster in U.S. history and exceed the damage caused by the 1989 Exxon Valdez accident that leaked an estimated 10.8 million U.S. gallons on to the shores of Alaska.
