Newsweek, June 7, 2010
By Sharon Begley
Giant plumes of crude oil mixed with methane are sweeping the ocean depths with devastating consequences. ‘I’m not too worried about oil on the surface,’ says one scientist. ‘It’s the things we don’t see that worry me the most.’
It was in mid-May that independent scientists—not any of the officials or researchers working for any of the government agencies on scene at the Deepwater Horizon disaster, let alone BP—first detected the vast underwater plumes of crude oil spreading like Medusa’s locks from the out-of-control gusher in the Gulf of Mexico. BP immediately dismissed the reports, and in late May CEO Tony Hayward flatly declared “there aren’t any plumes,” stopping just short of accusing the scientists of misconduct. Federal officials called the scientists’ claim “misleading, premature and, in some cases, inaccurate.” Moreover, continued a statement from the National Oceanic and Atmospheric Administration, any oxygen depletion in the surrounding waters due to plumes is not “a source of concern at this time,” and critics blaming dispersants for the plumes had “no information” to stand on. NOAA administrator Jane Lubchenco, a respected oceanographer when President Obama tapped her to lead the agency, insists there are no plumes, only “anomalies”—though last week she acknowledged the possibility of oil beneath the surface.
Now it is increasingly clear that the initial reports of undersea oil were right, that life-giving oxygen in the water column is indeed being depleted, and that unless the laws of chemistry have been repealed, dispersants are likely worsening the tentacles of undersea crude. What might have been just another oil spill—albeit a bad one—has been transformed into something unprecedented. Even if the containment dome lowered into place late last week continues to siphon off some of the leaking crude, the Deepwater Horizon disaster will enter the record books not for how much but for where: an enormous release of crude oil not only onto vulnerable shorelines and fragile marshes but into the largely unexplored depths of the sea. The consequences for the delicate balance of existence in the vulnerable ecosystems of the gulf, and for the vast cycles of nature that sustain life there and beyond, are as incalculable as they are potentially devastating.
Their presence has blown to smithereens the cliché that oil floats on water. That correctly describes what happens when pure crude spills into the sea from a well in shallow water or a tanker at the surface, as happened with the Exxon Valdez. But when a gusher is 5,000 feet down, consists of a mix of crude oil and dissolved methane, and is being disgorged under tremendous pressure and temperature, studies predict that the physical and chemical properties of the spill will undergo an ugly alchemy. “The dispersants are changing the chemistry and physics of the oil,” says biological oceanographer Ajit Subramaniam of Columbia University’s Lamont-Doherty Earth Observatory. “They are creating microlayers of oil that are being carried by the deep currents.” Even without dispersants, the crude gets broken into zillions of droplets suspended in the water column and corralled there, prevented from rising to the surface. The result is the undersea plumes that oceanographer Samantha Joye of the University of Georgia and colleagues first detected from the research vessel Pelican three weeks after the blowout. Despite years of research showing that undersea oil might form such plumes, BP’s Hayward insists it cannot. “Oil floats!” he repeatedly says.
Making matters more interesting, the chemical dispersants that work fairly well on surface spills, breaking apart oil slicks into droplets that degrade more quickly than a contiguous layer, may be exacerbating the undersea-oil problem. A 2007 report by the Minerals Management Service—which OK’s oil and gas leases—on the environmental consequences of oil and gas drilling on the outer continental shelf concluded that an underwater plume is a real possibility: “The use of dispersants on oil spills … could cause these compounds to reach the deeper water reef areas.” BP has pumped 185,000 gallons of dispersant onto the out-of-control wellhead (plus 800,000 on the surface). That is causing more of the gushing crude to break up into the very form unlikely to rise to the surface. There have been no suggestions that BP intended to keep the worst of the spill out of sight.
After NOAA questioned the finding of deepwater oil plumes (but now has two boats using sonar to look for plumes), the National Science Foundation stepped in with the kind of support that matters: cash. With “rapid response” grants from the foundation, scientists are searching for plumes and trying to assess their impact. As far as scientists can tell, the undersea oil is actually a witch’s brew of crude mixed with dissolved methane, stretching 15 miles long, 5 miles wide, and 300 feet thick in the case of one plume detected by the Pelican, and 22 miles long, 6 miles wide, and 3,000 feet thick in the case of a plume found by University of South Florida researchers aboard the WeatherBird II last week. The latter plume reaches all the way to the surface.
NOAA’s skepticism about plumes is correct on one point. Contrary to what the phrase conjures up, oil plumes are not black serpentines. The USF researchers caught one on camera last week, but in general they can be detected only by sophisticated instruments lowered into the depths. Samples hauled up do not even look black, though when they are run through a filter, black specks are revealed.
These undersea rivers of oil, though not nearly as concentrated as oil at the surface, are likely to affect the gulf through two mechanisms. The first is oxygen depletion, which has been estimated at 30 percent in the plumes. The other will be direct toxic effects of the oil and methane. Leatherback turtles and sperm whales dive to the 3,200-foot depths where plumes have now been detected, and aren’t smart enough to take evasive action. “They don’t necessarily recognize the plumes as something dangerous,” says marine scientist Ellycia Harrould-Kolieb, who works with the green group Oceana. Sharks, shrimp, and squid are all inhabitants of the deep, which would protect them from a Valdez-type spill on the surface, but now puts them in the crosshairs. Marlin, snapper, and grouper swim hundreds of feet down. One of the biggest losses may be bluefin tuna. Already imperiled from overfishing, the species breeds only in the Mediterranean Sea and the gulf. “This could spell the end to bluefin,” says Harrould-Kolieb. Even small bits of crude, like those in the plumes, can suffocate fish by gunking up their gills.