A university scientist and the federal government say they have found persuasive evidence that oil from the massive Gulf of Mexico spill is settling on the ocean floor.
The new findings, from scientists at the University of South Florida and from a broad government effort, mark the latest indication that environmental damage from the blowout of a BP PLC well could be significant where it’s hardest to find: deep under the Gulf’s surface.
The amount of oil that has settled in the sediment—and the extent of damage it has caused—remains unclear. But scientists who have been on research cruises in the Gulf in recent days report finding layers of residue up to several centimeters thick from what they suspect is BP oil.
The material appears in spots across several thousand square miles of seafloor, they said. In many of those spots, they said, worms and other marine life that crawl along the sediment appear dead, though many organisms that can swim appear healthy. How the death of organisms in the sediment might affect the broader Gulf ecology is something scientists are studying.
Tests to determine how much of the material on the seafloor matches the spilled oil are continuing. But the fact that tests now have started to link some oil in the sediment to the BP well could add to the amount of money BP ends up paying to compensate for the spill’s damage.
Under federal law, companies found responsible for an oil spill have to pay compensation for the resulting environmental harm. The more BP’s oil is found to have polluted the Gulf floor and killed marine life there, the more money the government is likely to press BP to pay.
The test results also raise questions about the possible downsides of the government’s use of chemical dispersants to fight the spill.
Under federal direction, about 1.8 million gallons of dispersants were sprayed on the spilled oil in an effort to break it up into tiny droplets that natural ocean microbes could eat up. At the time, officials said the dispersants shouldn’t cause oil from the spill to sink to the seafloor. However, more recently, a federal report said dispersants may have helped some spilled oil sink to the sediment.
Scientific teams have reported in recent months finding a strange substance on the Gulf floor, in some cases as far as about 80 miles from BP’s ill-fated Macondo well, which blew out in April and spilled an estimated 4.1 million barrels of oil into the Gulf before it was capped.
They have speculated that the substance—found as deep as 2,300 meters below the surface—was oil from the BP blowout. But, until now, they haven’t had this evidence from chemical tests.
David Hollander, an oceanographer at the University of South Florida, said in an interview that he and colleagues have just completed tests showing that the chemical profile of oil they found in Gulf sediment matches that from the blown-out BP well.
“The chemical signatures are identical,” said Mr. Hollander, who found the contaminated samples in an area of the Gulf floor off the Florida Panhandle. Although it’s conceivable the tests could show a false match with the BP oil, “the statistical probability of something like that is unimaginable,” Mr. Hollander said.
The federal government also has found oil matching Macondo oil in Gulf sediment, Steve Murawski, a top National Oceanic and Atmospheric Administration scientist, said in an interview. He declined to disclose how much sediment contamination the government found, or exactly where in the Gulf it was, saying experts still are analyzing the test results.
The government plans to publish details of its findings later this month.
BP, too, is testing the Gulf environment for oil contamination, and some of its results will figure into the coming federal report. Laura Folse, director of science and technology for BP’s Gulf Coast restoration effort, declined to say whether BP found oil matching Macondo oil in the Gulf sediment.
She also said she couldn’t comment on Mr. Hollander’s findings because she hadn’t seen them.
Oil from a given location has a telltale chemical pattern—a distinct mix of the various hydrocarbon compounds that make up oil. Running an oil sample through special machines spits out a graph, or fingerprint, of the amount of each component in that oil.
Normally, scientists draw these fingerprints by measuring certain compounds in oil known as “biomarkers.” The federal government used that method in its tests, NOAA’s Mr. Murawski said.
Mr. Hollander and his colleagues found their sediment samples lacked enough of those biomarkers to test, he said. So they examined a different set of compounds in the oil. They measured the quantity of two groupings of carbon atoms that each compound contained.
When they compared the resulting graph to one from a known sample of Macondo oil, the graphs were “sitting right on top of each other,” signaling a match, Mr. Hollander said.
Mr. Murawski said the method Mr. Hollander used is “accepted” but “not standard,” though he stressed he wasn’t criticizing Mr. Hollander’s work.
Samantha Joye, a University of Georgia oceanographer, also has found what she believes to be evidence of BP oil in Gulf sediment. She is awaiting lab results tracing the chemical fingerprints of sediment samples she took.
On a research cruise in the Gulf that ended Friday, she saw worms that crawl along the Gulf floor “just decimated,” she said. But eels and fish, which can swim away, often appeared fine, she said.
The federal government made sure to test sediment in areas where Ms. Joye and Mr. Hollander said they found oil.