Saving Lousiana wetlands from Gulf spill

An island in Barataria Bay, La., that is home to hundreds of brown pelican nests as well at terns, gulls and roseate spoonbills is affect by oil from the Deepwater Horizon disaster. (Gerald Herbert/AP)

Oil from the spill in the Gulf of Mexico is creeping closer to southern Louisiana’s fragile wetlands and the best way to deal with it once it lands just might be to set it on fire.

So far about 65 miles of Louisiana’s coastline has been hit by the spill, the Christian Science Monitor said. Oil has traveled as many as 12 miles inland.

The CS Monitor said there are several ways to deal with contaminated wetlands, including strengthening microbes, cutting marsh grass and conducting controlled burns. But like many things, the Monitor says, not all solutions are created equal.

Not all of them may be practical in this situation, cautions Qianxin Lin, a coastal ecologist at Louisiana State University in Baton Rouge.

Part of the challenge is that the oil reaching the coast has had several days to weather – essentially losing the components that evaporate most readily, leaving a thicker, watery mousse to move inland with winds and tides.

Strengthening microbes in the wetlands by feeding them nitrogen and phosphorous could help to degrade oil in the contaminated areas, the Monitor says.

The danger in this method, however, is that the oil is affecting tidal wetlands. Lin says this method is best suited for marsh areas.

Tides could carry the nutrients out into the Gulf, triggering algae blooms, which already are a problem offshore.

Marsh sediment also does not have much oxygen in it. So even if fertilized, the microbes might not become as active, the Monitor says.

Clean up crews could cut the oiled marsh grass and leave the roots so new grass could grow, but moving people or machines through the marsh could send oil deeper into the sediment. That oil could affect the ecosystem for decades.

Experts told AFP that moving grasses and marshes around could cause more damage.

Cleaning up the maze of marshes, where there’s nothing to stand on and shallow-bottomed boats are needed to navigated the narrow channels, is a logistical nightmare.
Unlike a beach or rocky shore, crews can’t just drive up with a backhoe or a mop. And there are plenty of places for frightened wildlife to hide from rescue workers as the oil slowly smothers them.

That means the best option is to leave the oil there or burn it off, AFP said.

The Monitor says burning has worked in the past.

The approach appears to have been successful in dealing with a relatively small spill triggered by hurricane Katrina, according to Amy Merten, a researcher with the National Oceanic and Atmospheric Administration.

Merten wrote in a report that oil from a Chevron Oil tank destroyed by Katrina was blown into an adjacent marsh when hurricane Rita came through. Burning the marsh removed between 80 and 90 percent of the oil, the Monitor says.

Interestingly, the burn took place months after Rita hit, suggesting that, under some conditions, there need not be an extreme sense of urgency if authorities choose this option.

Enough residue remained to be deemed a hazard to wildlife for a time. But after about two years, monitoring efforts showed that the ecological structure and function of the burned marsh returned to closely match those of adjacent, unburned and untainted marshes, Lin says.

Still, the technique might not work if water levels in the marsh are too low, the Monitor says, because heat from the fire will destroy the roots.