July 28, 2010
News headlines state that cleanup workers are having a hard time finding oil.
Sounds good, right?
Actually, if BP had let things run their course:
Instead, BP has used millions of gallons of dispersants to hide the oil by breaking it up, so it sinks beneath the surface.
That means that oil-skimming vessels can’t find it or suck it up. As the Times-Picayune pointed out on July 16th:
The massive “A Whale” oil skimmer has effectively been beached after it proved inefficient in sucking up oil from the Gulf of Mexico spill.
The oil is too dispersed to take advantage of the converted Taiwanese supertanker’s enormous capacity, said Bob Grantham, a spokesman for shipowner TMT.
He said BP’s use of chemical dispersants prevented A Whale, billed as the world’s largest skimmer, from collecting a “significant amount” of oil during a week of testing that ended Friday.
“When dispersants are used in high volume virtually from the point that oil leaves the well, it presents real challenges for high-volume skimming,” Grantham said in a written statement that did not include oil-collection figures from the test.
Similarly, the use of dispersants means that Booms can’t stop it from hitting the shore. As marine biologist and oil spill expert Paul Horsman explains, using dispersants and oil booms are competing strategies. Specifically, breaking something down into tiny bits and dispersing it throughout a mile-plus deep and hundreds-miles wide region (the reason massive amounts of dispersants are being applied at the 5,000 foot-deep spill site as well as at the surface) makes it more difficult to cordon off and contain oil on the surface (the reason booms are being used).
And Corexit might be killing the oil-eating bacteria which would otherwise break down the oil. University of Georgia scientist Samantha Joye notes that scientists have no idea how the large quanties of dispersant will effect the Gulf’s microbial communities (for more information, watch part 1, part 2, part 3, part 4 and part 5 of Dr. Joye’s July 13th press conference).
Moreover, as MSNBC notes, oil-eating bacteria are less active in deepwater, where much of the oil sinks after treatment with dispersants:
Some note that little is known about the deepwater ecosystem — or how the oil and dispersants will react under extremely high water pressure, very low temperatures, limited oxygen and virtually no light.
The conditions at the bottom of the Gulf also could affect the bacteria that help break down the oil near the surface, as they are less active in cold temperatures than in the warm surface waters, and they may be less abundant in the deep.
“We know that the surface material has been degrading,” says Ralph J. Portier, professor of environmental studies at LSU. “But what about the microbial population at depth?”
As Scientific American points out:
The last (and only) defense against the ongoing Deepwater Horizon oil spill in the Gulf of Mexico is tiny—billions of hydrocarbon-chewing microbes, such as Alcanivorax borkumensis. In fact, the primary motive for using the more than 830,000 gallons of chemical dispersants on the oil slick both above and below the surface of the sea is to break the oil into smaller droplets that bacteria can more easily consume.
“If the oil is in very small droplets, microbial degradation is much quicker,” says microbial ecologist Kenneth Lee, director of the Center for Offshore Oil, Gas and Energy Research with Fisheries and Oceans Canada, who has been measuring the oil droplets in the Gulf of Mexico to determine the effectiveness of the dispersant use. “The dispersants can also stimulate microbial growth. Bacteria will chew on the dispersants as well as the oil.”
[But] colder, deeper waters inhibit microbial growth. “Metabolism slows by about a factor of two or three for every 10 degree[s] Celsius you drop in temperature,” notes biogeochemist David Valentine of the University of California, Santa Barbara, who just received funding from the National Science Foundation to characterize the microbial response to the ongoing oil spill. “The deeper stuff, that’s going to happen very slowly because the temperature is so low.”
At the same time, the addition of … dispersants deep beneath the surface is having uncertain effects; it may even end up killing the microbes it is meant to help thanks to the fact that Corexit 9527A contains the solvent 2-butoxyethanol, which is a known human carcinogen and toxic to animals and other life.
Mother Jones provides additional details:
David Valentine … warns the stuff may be riskier than just its toxicity. Corexit may undermine the microbes that naturally eat oil.
Some of the most potent oil-eaters— Alcanivorax borkumensis —are relatively rare organisms that have evolved to eat hydrocarbons from naturally occurring oil seeps. Valentine tells Eli Kintisch at Science Insider that after spills, Alcanivorax tend to be the dominant microbes found near the oil and that they secrete their own surfactant molecules to break up the oil before consuming the hydrocarbons. Other microbes don’t make surfactants but devour oil already broken into small enough globs—including those broken down by Alcanivorax.
What we don’t know is how the surfactants in Corexit and its ilk might affect the ability of Alcanivorax and other surfactant-makers to eat oil. Could Corexit exclude Alcanivorax from binding to the oil? Could it affect the way microbes makes their own surfactants? Could Corexit render natural surfactants less effective?
The National Science Foundation has awarded Valentine a grant to study the problem.
So it’s not a good thing that clean up workers can’t find the oil. It means that the oil will lurk under the surface, in deeper waters where bacterial activity is slower, poisoning the sealife that lives beneath the surface, and washing back up during storms for years to come.
Even Admiral Thad Allen, the government’s point man for the crisis, said that breaking up the oil has complicated the cleanup. As AP reported on June 7th:
The hopeful report was offset by a warning that the farflung slick has broken up into hundreds and even thousands of patches of oil that may inflict damage that could persist for years.
Coast Guard Adm. Thad Allen, the government’s point man for the crisis, said the breakup has complicated the cleanup.”
Dealing with the oil spill on the surface is going to go on for a couple of months,” he said at a briefing in Washington. But “long-term issues of restoring the environment and the habitats and stuff will be years.”
And Admiral Allen admitted in his press conference yesterday that oil could re-surface far into the future:
[Question] There have been reports of very large undersea plumes of oil thousands of feet below the ocean’s surface. So when you say there’s the possibility of the shore being impacted for four to six weeks, how do you come up with that four to six week number? And are you taking into account these very large plumes of oil that are out there and very difficult to sort of gauge where they’re going?
[Admiral Allen] What we’re going to continue to watch for is the oil we can’t see…. But the ultimate impact of this spill… whether or not oil surfaces at a later date will be the subject of long-term surveillance…. Impacts are going to go on for a long, long time.
As Congressman Markey said today, BP has made the Gulf “a toxic bowl” that will “haunt this region” for years, because “all of that oil is still under the surface”:
This article was posted: Wednesday, July 28, 2010 at 4:57 am