Think of an oil spill and you picture a black tide engulfing beaches and drowning shorebirds and sea turtles in crude. These are the images of the Exxon Valdez accident, which spilled nearly 11 million gal. of oil into Alaska's Prince William Sound in 1989. The oil that escaped from the tanker eventually coated 1,300 miles (2,100 km) of pristine Alaskan coastline and covered 11,000 sq. mi. (28,000 sq km) of ocean in an inky slick.
The Valdez disaster was the biggest spill in American history until now. Since April 20, when the Deepwater Horizon oil rig exploded and triggered an underwater well blowout, at least 20 million bbl. of crude and counting have poured into the Gulf of Mexico. And, yet, where is all the oil?
On Sunday, I took a boat trip from the fishing port of Venice in the southeastern reaches of Louisiana, where the road ends and the marshlands begin. Traveling with Angelina Freeman, a coast scientist with the Environmental Defense Fund (EDF), we saw no Valdez-style wave of crude drenching the bayou. We did see some oil ringing the tall wetland grasses near Pass a Loutre, La., by the mouth of the Mississippi River the grasses looked as if they had been dipped in chocolate. I could smell the tang of hydrocarbons. But if this is really the "oilpocalypse," as some observers have dubbed the Deepwater catastrophe, it is not apparent on the surface.
That is what makes the Gulf of Mexico spill so much more insidious than that of the Valdez in Alaska, and potentially much more destructive. The oil leaking from the broken well at the bottom of the ocean is everywhere but nowhere you can see. While a tanker spills the entirety of its contents on the surface of the ocean at once, creating an avalanche of crude and immediate and horrific photographic images the Gulf spill gushes continuously, out of sight, from 5,000 ft. (1,500 m) below the ocean's surface. The busted well is a fountain that the Obama Administration recently admitted could flow uninterrupted until August. Think of it less as an acute trauma than a chronic, progressive disease that doctors can diagnose but cannot cure.
So where is the oil hiding? Scientists say some of it is spreading underwater, in plumes that extend thousands of feet below the surface. But BP CEO Tony Hayward disputes those claims. "The oil is on the surface," Hayward said on Sunday while touring a staging area for cleanup workers in Louisiana. He said there was "no evidence" that enormous reservoirs of oil were suspended undersea.
However, two independent university research teams from the University of South Florida and the University of Georgia (UGA) have reported direct evidence of underwater oil. Samantha Joye, a marine scientist at UGA, has been aboard the university's ongoing research voyage in the Gulf and blogging from the ship; she reported on Monday that the team could see oil in water samples collected from plumes nearly 1,000 ft. (300 m) below the surface. "Seeing is believing," she blogged, and after nearly a month of continual obfuscation by BP on the technical details of the spill, Joye's words carry a lot more weight than Hayward's.
But seeing is exactly what will be hard to do with the Gulf spill, now and in the months ahead. The oil underwater will do untold amounts of damage, even if it's invisible. "It's out of sight and out of mind, but it will have a huge effect on the marine life that oscillates in that zone," says Doug Rader, the chief ocean scientist for the EDF.
There is, of course, oil on the surface of the Gulf as well. The slick is thousands of square miles wide, and it will continue to grow and shrink, mutated by hundreds of thousands of gallons of chemical dispersants and the complex effects of ocean currents and winds. We will see the oil wash up along the coastlines of the Gulf in the southern wetlands of Louisiana, for instance, where oil has already begun seeping in then perhaps be carried out again by the tides. BP and the Coast Guard, to their credit, will throw down hundreds of miles of shore boom and other physical defenses against the emerging oil, but as long as the well flows, it will keep coming. "We're not really cleaning up the oil we're just smudging it on the edges," says Ian McDonald, an oceanographer at Florida State University who has closely studied the spill. "So much of this is still hidden."
That makes the work of scientists like Freeman just as vital as that of the hundreds of boaters pulling boom duty for BP. As we cruised around Pass a Loutre, Freeman stopped the boat near oily spots and took medicine-bottle-size water samples, noting the exact locations. Those samples will go back to Louisiana State University where Freeman did her graduate work for scientists to chemically fingerprint any oil and trace it back to the original spill (a method that works much better than dipping a finger and tasting not recommended). "It lets us track what's actually going on with this spill," says Freeman.
Meanwhile, U.S. Attorney General Eric Holder announced on Tuesday that the federal government would launch criminal and civil investigations into the spill to trace its original causes. "We will closely examine the actions of those involved in the spill. If we find evidence of illegal behavior, we will be extremely forceful in our response," Holder said in New Orleans.
Likewise, scientists will need to keep watching and measuring carefully. That will be especially true for the invisible, underwater environment, where oil plumes pose a toxic threat to sea life. In this case, it is what we can't see that can and will continue to hurt us.