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Oil spill not cause of record-size dead zone in Gulf

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Posted: Aug 2, 2010 10:29 PM by Ashley Rodrigue
Updated: Aug 2, 2010 10:39 PM
Source: WBRZ

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Topics: dead zone, oil spill, team, scientists, dispersants, oxygen, Mississippi River

The oil spill apparently hasn't made the annual "dead zone" in the Gulf grow.

It's where nothing lives in an area about the size of New Jersey. It's caused by a lack of oxygen in the water. The predictions on the record-size were made before the spill and the measurements matched up, as if the oil was never there.

A team of scientists found one of the largest dead zones on record-- about 7,700 square miles of little to no oxygen along the continental shelf. LSU professor Dr. Robert Turner says the cause is high levels of nitrogen spilling into the Gulf from the Mississippi River, which creates algae that works opposite of plants on land.

"In the bottom layer, the microbes, the bacteria chew it up, turn the organic matter into CO2, and in the process, they consume oxygen," said Turner.

Turner says it's been years since the team has seen a dead zone this size. However, he's the first to say oil isn't the reason.

"There isn't that much carbon brought in by the oil, under the best of circumstances, as far as we can tell, to make much of a dent in all the carbon that's produced from the fertilizer effect of the nutrients coming down the river," said Turner.

Environmental Sciences professor Dr. Ralph Portier at LSU agrees and says the same for dispersants.

"In relation to 1.8 million gallons of dispersant," said Portier, "it's a very, very dilute quantity, if any, that could be affecting the dead zone."

As for the future?

"The oil in the long term may move in to these areas and may have a lingering problem," said Portier, "or we may have a different kind of a dead zone."

Scientists say this year's dead zone should disappear by December. Tropical systems can also help break the zone up sooner.

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