Thursday, May 20, 2010

BP oil spill: Measures to mitigate wetland damage, stem flow continue.

About 40 percent of the nation's coastal wetlands are clumped along southern Louisiana, directly in the path of oil that was still gushing from a ruptured underwater well. Roughly 3.5 million gallons has escaped in the weeks since an oil rig explosion, and some is bearing down on the marshes as workers rush to lay protective boom.

"No question we will see some widespread impacts," Garret Graves, chairman of the Coastal Protection and Restoration Authority of Louisiana, said after an observation flight. "If we allow this oil to get into our coastal areas and fundamentally change the ecosystem, the consequences are profound."

Removing oil from wetlands is a huge challenge. Bulldozers can't simply scrape away contaminated soil, as they do on beaches. Cutting and removing oil-soaked vegetation could further weaken the fragile vegetation that holds the marshes together. Absorbent materials and detergents have limited effectiveness, Graves said.

If a thick enough layer of oil coats hardy swamp grasses and shrubs, scientists say it could shut down their equivalent of breathing -- absorbing carbon dioxide and releasing oxygen.

"You could literally suffocate the marsh," said Alex Kolker, a coastal systems specialist with the Louisiana Universities Marine Consortium.

Even worse, the oil could soak into the ground and poison roots, killing entire plants. With nothing to anchor it, the soil would wash away, accelerating a process that has cost Louisiana about 2,300 square miles of coastal marshes and barrier islands the last 80 years -- an area bigger than Delaware.

A spill-related loss of wetlands would ripple through the food chain they support, from tiny organisms to fish and birds.

"It's like you pull a thread on the shirt and it all comes apart," said Mark LaSalle, an ecologist at the Pascagoula River Audubon Center in Moss Point, Miss.

Or the damage could be less severe and the ecosystem could survive yet again.

"It's like when you get pneumonia," Kolker said. "There's a certain amount you can handle and bounce back, and there's a certain amount that will make you miserable but you'll survive, and there's a certain amount that will kill you."

All hinges on how much oil reaches the wetlands, and how soon workers can plug the leak from the stricken well pouring at least 200,000 gallons daily into the Gulf since the rig exploded and sank April 20.

From Texas to Florida, the Gulf region is laced with wetlands. But Louisiana's are most directly threatened by the encroaching oil and by far the most plentiful, even after the state has suffered 80 percent of U.S. coastal wetland loss.

Wetlands feed and provide nesting and spawning grounds for multitudes of waterfowl and fish. Menhaden, the top commercial fish species in the lower 48 states and an ingredient in products ranging from insecticide to chicken feed, spends its crucial first months of life nibbling decomposed marsh grass.

"Lose the marshes and we lose menhaden," said Andy Nyman, a wetland and wildlife ecologist at the Louisiana State University Agricultural Center.

Wetlands perform the kidney-like function of filtering chemicals and other pollutants from waters, and they prevent floods by soaking up excessive waters like sponges and releasing them when levels recede. Historically, they have shielded inland cities such as New Orleans from the worst of the Gulf's tidal surges during hurricanes and tropical storms.

As land area of wetlands has declined over the years, so has their effectiveness.

Beginning in the 1930s, levees built along the Mississippi River to ward off flooding curtailed flow of fresh water into estuaries, killing off plants unable to live year-round in salt water. That accelerated erosion and converted former wetlands into open water.

The river previously deposited layers of new mud to replenish the marshes. Now, the levees prevent that.

As part of our responsibility to show the immediate and long term effects of this catastrophic oil spill on accelerated soil erosion your website via measures to mitigate wetland damage, solutions to control beach erosion, and methods to re-vegetate those areas damaged by soil pollution helps in its recovery.

… read more

News of this theme will be posted here.

No comments: