The long term environmental impact of the Deepwater Horizon oil spill remains a question mark, but generally the feeling is it’s not good.
But the past has something to tell us about how well the Gulf of Mexico can recover from accidents, according to speakers at a University of Houston symposium on the spill. (see other posts from event here, here and here).
Naturally occurring oil seeps in the Gulf of Mexico produce the equivalent of one or two supertankers spilling per year, said Wes Tunnell, associate director of the Harte Research Institute for the Gulf of Mexico studies at Texas A&M in Corpus Christi. This has helped create an active community of bacteria that do well at eating oil.
“The Gulf of Mexico is one of most resilient places on earth when it comes to handling oil,” Tunnell said.
Tunnell has followed the impact of oil that washed ashore on Texas and Mexico shores since the epic Ixtoc blowout of 1979. On sandy beaches the environment generally returned to its pre-spill conditions (based on the Environmental Sensitivity Index) in around three years.
But anecdotaly, fisherman in a Mexican mangrove swamp that was inundated with oil from Ixtoc say mussels that once grew in abundance on the roots of the trees have not returned, Tunnell said. That may be a better analogy for what could happen to the marshes in Louisiana that were hit by oil.
But that hardly means going into the marshes with vacuum hoses is the best way to deal with a spill. Tunnell and Donald Davis, the former director of Louisiana’s Oil Spill Coordinator’s Office, said more often than not that actually makes things worse.
“One of best ways to clean the marshes is don’t do anything to them,” Davis said. “You can do much more damage to fragile marshes bringing boats and hoses in there.”
Unlike in cold climates like Alaska, the heat and bacteria can do a better job of breaking down oil in southern marshes.
And believe it or not, sometimes burning oil-soaked marshlands is the best solution to a lousy situation.
Davis’ former group LOSCO, conducted extensive research into what conditions were needed for burns to be successful without destroying a marsh’s ability to grow back. A minimum of 2 centimeters of water in the marsh at the time of the burn was one needed element.
For example, a large marsh next to Chevron’s Empire, La. oil terminal was soaked by oil following the rupture of a storage tank during Hurricane Katrina. It was an area that was important for migratory birds and needed to be restored.
A controlled burn of the marsh removed 80 to 90 percent of the oil, with recovery of plant life following soon after. “From operational and environmental perspectives, burning was the appropriate cleanup method for this site,” concluded an NOAA study.
Speaking of controlled burns…
Here’s a music video shown at the UH oil spill conference where Tunnell and Davis spoke. It was put together by some of the BP workers who were in charge of the 420 or so in situ burns done of oil slicks out on the open water this past summer. The crews burned an estimated 270,000 to 300,000 barrels of oil.