Methane levels add new concerns

New Orleans: It is an overlooked danger in the oil spill crisis: The crude gushing from the well contains vast amounts of natural gas that could pose a serious threat to the Gulf of Mexico's fragile ecosystem.

The oil emanating from the seafloor contains about 40 per cent methane, compared with about 5 per cent found in typical oil deposits, said John Kessler, a Texas A&M University oceanographer, studying the impact of methane from the spill.

That means huge quantities of methane have entered the Gulf, scientists say, potentially suffocating marine life and creating "dead zones" where oxygen is so depleted that nothing lives. "This is the most vigorous methane eruption in modern human history," Kessler said.

Flammable substance

Methane is a colourless, odourless and flammable substance that is a major component in the natural gas used to heat people's homes. Petroleum engineers typically burn off excess gas attached to crude before the oil is shipped off to the refinery. That's exactly what BP has done as it has captured more than 28.3 million litres of crude from the breached well. A BP spokesman said the company was burning about 850,000 cubic metres of natural gas daily from the source of the leak, adding up to about 12.74 million cubic metres since the containment effort started 15 days ago. That's enough gas to heat about 450,000 homes for four days.

But that figure does not account for gas that eluded containment efforts and wound up in the water, leaving behind huge amounts of methane. Scientists are still trying to measure how much has escaped into the water and how it may damage the Gulf and it creatures.

The dangerous gas has played an important role throughout the disaster and response. A bubble of methane is believed to have burst up from the seafloor and ignited the rig explosion. Methane crystals also clogged a four-storey containment box that engineers earlier tried to place on top of the breached well.

Now it is being looked at as an environmental concern.

The small microbes that live in the sea have been feeding on the oil and natural gas in the water and are consuming larger quantities of oxygen, which they need to digest food. As they draw more oxygen from the water, it creates two problems. When oxygen levels drop low enough, the breakdown of oil grinds to a halt" and as it is depleted in the water, most life can't be sustained.

The National Science Foundation funded research on methane in the Gulf amid concerns about the depths of the oil plume and questions what role natural gas was playing in keeping the oil below the surface, said David Garrison, a programme director in the federal agency who specialises in biological oceanography.

"This has the potential to harm the ecosystem in ways that we don't know," Garrison said. "It's a complex problem."

BP CEO Tony Hayward on Thursday told Congress members that he was "so devastated with this accident", "deeply sorry" and "so distraught."