Cleanup efforts shortly after the spill. Image: Wikimedia Commons
Gail Irvine regularly finds oil polluting Alaska's Prince William Sound. But the oil isn't fresh—it's left over from the 1989 Exxon Valdez oil spill, and it's still harming marine life a quarter century later.
Irvine, of the United States Geological Survey, has been monitoring the sound and the coastline of the Shelikof Strait, southwest of the spill, for 20 years, and has just recently discovered these pockets of oil that have persisted behind large boulders along the coastline. What’s more, the oil appears to have broken down very little and has the chemical makeup of oil that is just 11 days old, meaning it isn't going anywhere anytime soon.
“Every chemist who has looked at this has been surprised,” Irvine said. ”These are at high wave-energy sites, it’s not the kinds of areas where oil would have been predicted to have persisted, especially because it has barely been weathered.”
Her research, which will be presented today at Honolulu’s Ocean Sciences Meeting, raises new concerns about the lasting impacts of oil spills and suggests that the area still hasn’t completely recovered from one of the worst ecological disasters in history.
On March 24, 1989, the Exxon Valdez tanker spilled 11 million gallons of oil into the sound. Within days, the oil covered 1,300 miles of coastline and killed countless sea birds, otters, fish, and other marine life, sparking a massive, international cleanup effort. The company allegedly hasn’t paid all of the money it owes for the cleanup, which took four years and cost $2 billion.
Until last year, otters and other foraging marine mammals still showed chemical markers of oil exposure, according to Irvine.
In her study, she found that there are still traces of oil that can be found in mussel populations and in the sound’s water column.
“The places in the past where oil has been noted to persist have been quite protected areas such as salt marshes, where there’s not much physical removal of oil,” she said. “But one of the lessons learned here is that there’s a persistence of what we’d call subsurface oil.”
Oil is still clinging to boulders and persisting in the waters surrounding them. Image: Gail Irvine
Irvine says that, despite the pockets of oil that remain across her six test sites around the sound and in the strait, the sound is faring better.
“There’s still oil out there, but the amount is decreasing,” she said. “The fact that this is still out there might be applicable to other areas where we have this kind of habitat. It might change how we protect areas following spills.”