BP Plc is fighting the oil slick menacing the Gulf Coast with more than 160,000 gallons of a detergent-like chemical intended to break the oil down into tiny digestible particles.
The chemicals use the Gulf waves as a giant washtub to scrub the oil from the water, eventually dropping it to the seafloor where deep-sea microbes will feast on it for centuries, said James N. Butler, a professor emeritus of applied chemistry at Harvard University who has studied dispersants.
“It’s just like dish soap on grease,” Butler said. “The dispersant molecule has one end that likes oil, and the other that likes saltwater, and so it breaks into droplets,” he said in an interview.
BP engineers are working around the clock to find a way to stop a well, leaking since a drilling rig exploded and sank last month, from pouring more crude into the Gulf. The company, based in London, has stopped one of the three oil leaks, the U.S. Coast Guard said today.
There is no change in the official estimate that the well is leaking 5,000 barrels of oil a day. Even if the company stops the leak, it still has an oil slick estimated in recent days to be 600 miles in circumference to clean up. If BP can’t stop the oil at sea, it’s predicted to wash ashore in the coming days, killing wildlife and imperiling fish, shrimp and oysters in a region that supplies a third of the U.S.’s seafood.
While dispersants can help reduce the thick oil slick, the oil will still be out there, said Carl Hacker, resident ecologist at the University of Texas School of Public Health in Houston. The oil molecules could linger for a “geologic” period of time, perhaps thousands of years, said Terry Wade, deputy director at the Geochemical and Environmental Research Group at Texas A&M University in College Station, Texas.
BP is mounting a multipronged defense against the oil slick, using skimmer boats to scoop oil from the water’s surface, placing booms to repel it from shorelines, and burning the oil at sea. None of those methods, including dispersants, will be able to eliminate the oil threat, according to researchers who have studied cleanups.
“Once the oil reaches the shore, there are very few options,” said Pedro Alvarez, chairman of civil and environmental engineering at Rice University in Houston.
It takes five to 10 years for a shore to recover when oil reaches it, said Alvarez at Rice University. Using dispersants and other biotechnology can cut that time to two to four years, he said.
The Environmental Protection Agency, National Oceanographic and Atmospheric Administration and other federal agencies had to calculate a trade-off when approving the use of dispersants to control the spill, Charlie Henry, scientific support coordinator for NOAA, said in a press conference yesterday.
The chemicals are low in toxicity, but spread the oil further, potentially exposing more sea life, Henry said. The agencies decided that using chemicals at sea was preferable to allowing the oil to come ashore, where it would have a more deadly effect on wildlife and fisheries, he said.
BP has been pleased with the early results of an effort to inject dispersants deep into the water directly above where the oil’s escaping, said Bill Salvin, a BP spokesman at the Joint Information Center in Robert, Louisiana.
Oil is leaking from pipes connected to a wellhead on the seafloor nearly a mile below the water’s surface. The flows of crude followed an April 20 explosion that resulted in the death of 11 workers and sinking of the Deepwater Horizon drilling rig owned by Transocean Ltd. and leased by BP.
BP conducted two tests of the undersea application, spraying about 3,000 gallons over the leaks in each test, Salvin said. Sonar monitors showed less oil rising to the surface after the dispersants were applied, he said.
BP released additional dispersant underwater last night, said David Mosley, a Coast Guard petty officer in the Joint Information Center. Mosley couldn’t quantify the amount of dispersant released.
No dispersant is being used today, as officials try to gage the effect the subsea releases have had, Mosley said.
Nalco Holding Co., of Naperville, Illinois, is providing much of the dispersants to BP for the oil fight. Dispersants include surfactants -- the same key molecules that make dish soap or detergent active, said Charlie Pajor, a spokesman for the dispersant manufacturer.
Nalco has sent all of the dispersants it held in stock to combat the Gulf oil spill, and is manufacturing more at a plant outside of Houston, Pajor said. BP had an additional 230,138 gallons on hand yesterday.
To work most effectively, the oil and chemicals need to be blended thoroughly, said Butler, the Harvard professor. BP is relying on waves and currents and winds at sea to mix the dispersant with the oil.
If BP is successful at injecting the dispersants deep underwater, the most sensitive creatures close-by will be marine organisms in the earliest stages of their lives, said Peter Wells, former head of coastal and water science at Environment Canada.
Crustaceans, shrimp-like organisms, and plankton could easily ingest the oil if it was broken into small enough particles and distributed through the water column.
Naturally seeping oil in the Gulf already feeds some microbes, but such organisms aren’t very prevalent, because other sources of food are more appealing, said Wade of Texas A&M.
“It’s like going into the super-market and instead of buying a steak or a potato, eating the floor tiles,” he said.
Microbes will eventually digest the oil, a process that could take thousands of years, he said.