From CNN.com today:
Oil from the Deepwater Horizon spill may have settled to the bottom of the Gulf of Mexico further east than previously suspected and at levels toxic to marine life, researchers reported Monday.
Initial findings from a new survey of the Gulf conclude that dispersants may have sent the oil to the ocean floor, where it has turned up at the bottom of an undersea canyon within 40 miles of the Florida Panhandle. Plankton and other organisms showed a "strong toxic response" to the crude, according to researchers from the University of South Florida.
"The dispersant is moving the oil down out of the surface and into the deeper waters, where it can affect phytoplankton and other marine life," said John Paul, a marine microbiologist at USF.
Nancy Rome is a documentarian and writer based in Baltimore. She sent us this thoughtful guest post.
The question on everyone's mind right now and for the foreseeable future is: Where has the oil gone?
Much of the scientific community scoffs at the White Houseâ€™s claim last week that 75% of the oil has been cleaned up, even going so far as to call the claim ludicrous, because tracking the spill is so difficult.
To say how much has really been cleaned up is nearly impossible, and oil continues to wash up "under" beaches and marshes on barrier islands and will continue to do so for some time.
If we still do not know exactly how much oil actually gushed from the Deepwater Horizon, then how can we know the exact amount that has been cleaned up?
Well, BPâ€™s â€śstatic killâ€ť seems to have finally plugged the leak in the Gulf of Mexico, more than 3 months after it began spewing oil into the ocean. (Though the final nail in the coffin wonâ€™t come until the â€śbottom killâ€ť succeeds.)
And despite the optimistic reports today, the amount of oil remaining in the gulf is still equivalent to at least four times the amount that spilled in the Exxon Valdez disaster, and possibly double that.
NOAA predicts that 26% of the oil is â€śresidualâ€ť or still residing in the gulf and that another 24% was â€śdispersedâ€ť but much of that may still be hanging around waiting for mother nature (a.k.a. bacteria) to break it down. Further, NOAA says some of the oil is â€śdissolvedâ€ť which doesnâ€™t mean the same thing as â€śdisappeared.â€ť So more than half of the oil could still be dwelling in the Gulf â€“ maybe as much as 8 Exxon Valdez spillsâ€™ worth.
And there are still many, many unanswered questions.
Oceana campaign director Jackie Savitz discussed the dangers of dispersants on CNNâ€™s â€śThe Situation Roomâ€ť last night, check it out:
And tomorrow she will testify before the full Senate Environment & Public Works Committee about the known effects of dispersants. Savitz will offer her perspective on use of Corexit, and will argue that dispersant use is â€śthe lesser of two evils.â€ť
Warning: what follows isnâ€™t exactly light reading.
The New York Times reported yesterday on the complicated task of performing necropsies -- i.e., animal autopsies -- on sea turtles and other creatures that have been found dead in the Gulf of Mexico since the spill started.
Itâ€™s not easy to determine the cause of death of these creatures. Of the 1,978 birds, 463 turtles and 59 marine mammals found dead in the Gulf since April 20th, few show visible signs of oil contamination.
And in the case of sea turtles, a more familiar culprit may be at fault: shrimp trawls and other commercial fishing gear that scoop up turtles as bycatch and prevent them from going to the surface to breathe.
Hereâ€™s a simplified breakdown of how the veterinary investigators begin to determine the cause of death:
Sea turtles can become coated in oil or inhale volatile chemicals when they surface to breathe, swallow oil or contaminated prey, and swim through oil or come in contact with it on nesting beaches.
As of yesterday, 32 oiled sea turtles have been found in the Gulf of Mexico and more than 320 sea turtles have been found dead or injured since the spill began April 20.
While some dead and injured sea turtles are found by search crews or wash up on the beach, some never will. Ocean currents often carry them out to sea where they can sink or be eaten by predators.
Our report shows that the ongoing oil spill can have the following impacts on sea turtles:
The most familiar victims of the oil spill are the ones with faces: birds, sea turtles, dolphins, whales.
But as the New York Times reports today, there are at least three extensive deep-sea coral reefs lying directly beneath the oil slick in the gulf. And coral reefs canâ€™t swim or fly away from the plumes of partly dispersed oil spreading in the deep sea.
Both oil and dispersants are toxic to corals and have been found to impede the ability of corals to grow and reproduce, and the effects are amplified when they are mixed, which may be the case with these plumes.
Itâ€™s unknown exactly how sensitive deep-sea corals are to oil and dispersants, though as Oceanaâ€™s Pacific science director Jeffrey Short told the Times, â€śIt might be locally catastrophic, particularly if thereâ€™s an oxygen-depleted mass that develops.â€ť
There is no truly effective way of cleaning up an oil spill. All the options available are not fully effective or have negative impacts.
Burning the Slick
Unfortunately, burning the oil is a no-win situation; it creates large, toxic plumes of smoke that can result in respiratory problems and eye, nose, throat and skin irritations in both wildlife and humans. Birds may also become disoriented in the smoke.
Burning may be the lesser of two evils as it removes large amounts of oil that can result in immediate and long-term impacts to wildlife in the area, including skin irritations, organ damage, reproductive failures, developmental abnormalities and death.
One plan involves building up almost 70 miles of barrier islands by dredging sand and mud, including some from the bottom of the Mississippi River, and depositing it onto the outer shores of the islands, a process that would normally require years of environmental assessment.
Sediments from the river are likely to be contaminated with a host of other chemicals, like mercury, which could add insult to injury in the already badly contaminated Gulf waters.
Some of these islands are home to bird and wildlife sanctuaries, including the Breton National Wildlife Refuge. The plan may not work because the barrier islands have shrunk significantly, in part as a result of human engineering that has altered the flow of Mississippi for a variety of reasons -- including in efforts to facilitate oil and gas production.