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Bacteria helped Gulf oil spill, but it's not so easy in Arctic

  • January 20, 2012 1:04 PM |  
  • By Quirks

bobmcdonald-190.jpgBy Bob McDonald, Quirks & Quarks

Scientists at the University of California Santa Barbara have shown that favourable ocean currents in the Gulf of Mexico made it easier for bacteria to break down oil spilled from the Deepwater Horizon drill rig disaster in 2010.

Using computer models, combined with data from samples taken from the water, the researchers demonstrated that the circular shape of the Gulf of Mexico causes ocean currents there to swirl around like soup being stirred in a pot.

The circular pattern confined most of the roughly 5 million barrels of spilled oil to the gulf area, preventing most of it from contaminating the Florida Keys and drifting up the eastern seaboard.

More importantly, it also meant that a bloom of oil-eating bacteria suspended in the water was returned to the site of the spill two or three times, like birds returning to a feeder. Each time the bacteria returned to the leaking oil well, their population increased so they were able to gobble up the hydrocarbons much faster than expected.

These bacteria metabolize oil, methane and other hydrocarbons the way we metabolize food, turning it into less harmful products such as carbon dioxide and water. They are one of nature's cleanup mechanisms and likely responsible for consuming most of the oil spilled into the Gulf.

This accelerated bacterial effect is one more in the long list of fortunate coincidences that made the Deep Horizon spill much less of an environmental disaster than it could have been. Even though it was the largest accidental oil spill in U.S. history and the cleanup of hundreds of kilometers of fouled shoreline still continues, it could have been worse. The spill happened in warm water where bacteria grow vigorously, the hot sun evaporated the lighter fractions of the oil more quickly off the surface, and the spill happened in a region surrounded by oil industry infrastructure, so cleanup technology was close at hand.

Carry the same scenario to the Arctic and we don't get off so easily.

A blowout or spill in the far north, especially in the cold dark winter, will be much more difficult to capture.

According to Fisheries and Oceans Canada, Arctic waters do contain cold-adapted, oil-eating microbes. However, they operate at slower metabolic rates than warm water species.

Ocean currents in the Arctic Ocean do circulate, but over a much larger area than the Gulf of Mexico, so it would take years for the bacteria to return to the same site, if they return at all. So any bacteria exposed to hydrocarbons will be swept away, which means new blooms will have to grow to replace them.

The cold temperatures also affect the nature of the oil, making it thicker and more viscous, which is harder for the bacteria to break down.

An oil spill on northern land takes even longer to break down, because oxygen levels in oil-soaked marshes and ponds go way down and bacteria cannot thrive as easily.

The scientists who conducted the study are suggesting that detailed modeling of local ocean currents should be carried out before drilling begins, to predict where the spilled material will go and how bacterial communities would respond. This is a very good idea, especially for the high Arctic.

The people cleaning up the Deepwater Horizon oil spill in the Gulf of Mexico had a lot of help from nature. In the Arctic, nature will lend a helping hand, but that hand will not be as strong as it was in the Gulf. Cleanup will be mostly our responsibility, which is one more reason to make sure the oil doesn't spill in the first place.

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