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Apr 30, 2010 6:08 PM by Melissa Canone

Oil Type Harder to Remove From Marsh

NOLA.COM-The potential environmental damage from the Gulf of Mexico oil spill as it washes into Louisiana coastal estuaries increased Friday with the news that the petroleum involved might not be the light, easily treated Louisiana Sweet Crude, but a thicker, more viscous type that will be harder to remove from the marsh.

"When we analyzed the sample we got, it turned out to be stuff that was much heavier than typical south Louisiana crude," said Ed Overton, an LSU professor and one of the state's experts on oil spills. "It looks like it could be something heavier.

"South Louisiana crude is the easier type to clean up and contain. This other stuff would be a whole different ball game. A much tougher ball game."

Overton cautioned that his lab analysis was based on a single sample, and he has urgently been trying to get others. "We need to know, because this could change how we go about attacking this thing.

"I've been telling people all week that since this is Louisiana sweet crude, treating it won't be a big problem. But now we need to confirm this heavier stuff as soon as possible."

Louisiana "sweet" crude is prized by refiners because it contains a high percentage of the volatile compounds that are used for making gasoline, and a small fraction of asphaltenes, heavier, non-combustible compounds that are most commonly used for roads and roofs.

While the volatile compounds have high toxicity and can pose serious health risks to plants, fish, wildlife and humans including cancers and death, they evaporate quickly once exposed to oxygen and sunlight and are easy to treat during spills, Overton and other clean-up experts said.

Chemical dispersants sprayed on these sweet crudes quickly break them up into small particles that can be attacked by bacteria in the water, which readily decompose it.

Asphaltenes have low toxicity, but they are resistant to dispersants, and emulsify with sea water to form a flowing gelatinous substance.

"Once that comes ashore, it will stick to our grasses along the edges of the marsh and will be very difficult to get off, and last a very long time," said Overton.

"Those grassy edges are some of the real keys to this habitat that drives these incredible estuaries. That's why I've been calling everyone I can think of to get another sample."

Getting a sample isn't easy as simple as dipping a bucket in the spill, Overton said. It must be collected by experts familiar with testing protocols.

"I've been asking everyone but the postman," he said. "So far no one can help. And we need to know because this will change everything.''

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