Potent chemicals fight oil slick

2010-05-05 12:49

Robert - A massive oil leak in the Gulf of Mexico has become the testing ground for a new technique where a potent mix of chemicals is shot deep undersea in an effort to stop oil from reaching the surface, and scientists are hurriedly weighing the ecological risks and benefits.

Crews battling the spill already have dropped more than 590 525 litres of the concoction - a mix of chemicals collectively known as "dispersant" - to try to break up the oozing oil, allowing it to decompose more quickly or evaporate before washing ashore.

The technique has undergone two tests in recent days that the US Coast Guard is calling promising, and there are plans to apply even more of the chemicals.

Needs approval

But the effect of this largely untested treatment is still being studied by numerous federal agencies, and needs approval from a number of them before it can be rolled out in a larger way.

"Those analyses are going on, but right now there's no consensus," said Charlie Henry, the scientific support co-ordinator for the National Oceanic and Atmospheric Administration.

"And we're just really getting started. You can imagine it's something we've never thought about."

Chemical dispersants carry complex environmental trade-offs: helping to keep oil from reaching sensitive wetlands while exposing other sea life to toxic substances.

Works like dish soap

The concoction works like dish soap to separate oil and water, but the exact chemical composition is protected as a trade secret.

The use of chemicals to break up the oil is just one of many techniques being used to try to prevent as much of the slick as possible from reaching land and contaminating sea life in the Gulf of Mexico since an oil rig exploded and collapsed, killing 11 workers and posing a hazard to a fragile ecosystem.

The undersea well has been spewing 757 000 litres a day since the explosion aboard the drilling rig Deepwater Horizon.

BP, the operator of the rig, has been unable to shut off the well, but crews have reported progress with using chemicals to reduce the amount of oil that reaches the surface.

During a test over the weekend, the dispersant was shot into the well at a rate of 34 litres per minute, according authorities. About 11 360 litres total were dispensed during the experiment.

No good options

More than 870 645 litres of dispersant are available, and more is being manufactured by Nalco Company of Naperville, Illinois, for use in the Gulf.

Neither Nalco, BP, rig owner Transocean or the Coast Guard have specified how much of the chemical brew will be needed to handle this spill.

One of the chief agents being used, called Corexit 9 500, is identified as a "moderate" human health hazard that can cause eye, skin or respiratory irritation with prolonged exposure, according to safety data documents.

The company says Corexit contains no known carcinogens or substances on the federal government's list of toxic chemicals.

Even some of the most ardent environmentalists, while concerned about the potential effects, aren't suggesting that the chemical concoction shouldn't be used in this case.

"It's basically a giant experiment," said Richard Charter, a senior policy adviser with Defenders of Wildlife. "I'm not saying we shouldn't do it; we have no good options."