If not, why would you pour 6.6 million litres of a synthetic petroleum solvent as a dispersant into the already oil-filled Mexican Gulf? Why are they letting BP continue to pour in this dispersant of relatively unknown effects on marine and coastal organisms (other than breaking up obvious plumes of oil to make the stuff less visible)? Because the pictures of heavy oil are bad PR? I’d rather let the world see, on a daily basis, what has been wrought by our thirst for oil, instead of trying to spread it around thinly and hoping some microbes will be able to break it down more easily that way – without a whole lot of evidence to back up that hope! Nature News has more on the growing debate over the impact of dispersed oil:
It may look unhealthy, but the cure could be worse.
USCG/Petty Officer 1st Class Tasha Tully
For years, Robert Twilley has worked to bridge the traditional academic divides between oceanography and coastal science.
“They really are not two separate systems,” says Twilley, a coastal scientist from Louisiana State University in Baton Rouge. “Whatever you do offshore certainly has implications to the shoreline and bay estuary environments.”
Now, Twilley is watching this lesson unfold before his eyes. As London-based BP continues to pour vast quantities of dispersants into the Gulf of Mexico, Twilley and many other scientists are growing increasingly concerned about the chemical soup that may be creeping onshore, as well as the poorly understood effects of dispersant in the water column at sea.
Initially, BP and the federal agencies involved in the spill response made the decision to use dispersant offshore to limit the amount of viscous oil washing up on beaches and into the wetlands, says Ed Overton, an environmental chemist at Louisiana State University. The idea behind the use of dispersants offshore, says Overton, “is you hold your nose and accept damage offshore to try to prevent damage onshore”.
So far, more than 6.6 million litres of dispersant have been applied: more than 4 million litres offshore and more than 2.5 million litres at the site of the leak. On the surface, dispersants are sprayed from planes over the surface of the oil. To reach oil at depth, dispersant is pumped from a vessel at the surface down to a wand pointed into the oil flowing from the broken wellhead, some 1.5 kilometres deep. Before the Deepwater Horizon spill, dispersants had only been used to treat surface oil.
Therein lies the worry, says David Valentine, a geomicrobiologist at the University of California in Santa Barbara. “It’s an experiment that’s never been performed before—to dump that much of an industrial chemical into the ocean.”
“My hunch is that when this thing started they wanted to keep the oil off the beaches, so they used the dispersants.” says Samantha Joye, a biogeochemist at the University of Georgia in Athens. “But no one thought it would go on this long.”
Now there are fears that that dispersed oil is making its way into shallow waters even as questions abound about the impacts on the water column at depth. We are trying “to unravel what’s truth and what’s purely speculation,” says Twilley.