Aug 20, 2010 6:21 AM by Sharlee Barriere

Major Study Charts Long-Lasting Oil Plume in Gulf

WASHINGTON (AP) - A 22-mile-long invisible mist of oil is
meandering far below the surface of the Gulf of Mexico, where it
will probably lester for months or more, scientists reported
Thursday in the first conclusive evidence of an underwater plume
from the BP spill.
The most worrisome part is the slow pace at which the oil is
breaking down in the cold, 40-degree water, making it a
long-lasting but unseen threat to vulnerable marine life, experts
Earlier this month, top federal officials declared the oil in
the spill was mostly "gone," and it is gone in the sense you
can't see it. But the chemical ingredients of the oil persist more
than a half-mile beneath the surface, researchers found.
And the oil is degrading at one-tenth the pace at which it
breaks down at the surface. That means "the plumes could stick
around for quite a while," said study co-author Ben Van Mooy of
the Woods Hole Oceanographic Institution in Massachusetts, which
led the research published online in the journal Science.
Monty Graham, a scientist at the Dauphin Island Sea Lab in
Alabama who was not involved in the study, said: "We absolutely
should be concerned that this material is drifting around for who
knows how long. They say months in the (research) paper, but more
likely we'll be able to track this stuff for years."
Late Thursday, federal officials acknowledged the deepwater oil
was not degrading as fast as they initially thought, but still was
breaking down "relatively rapidly." Jane Lubchenco, chief of the
National Oceanic and Atmospheric Administration, said agency
scientists and others were "working furiously" to come up with
actual rates of biodegradation.
She noted a bright spot from the slow breakdown of the oil:
Faster would mean a big influx of oil-eating microbes. Though they
are useful, they also use up oxygen, creating "dead zones" that
already plague the Gulf in the summer. Dead zones are not forming
because of the oil plume, Lubchenco said.
The underwate Noil was measured close to BP's blown-out well,
which is about 40 miles off the Louisiana coast. The plume started
three miles from the well and extended more than 20 miles to the
southwest. The oil droplets are odorless and too small to be seen
by the human eye. If you swam through the plume, you wouldn't
notice it.
"The water samples when we were right in the plume look like
spring water," study chief author Richard Camilli said. "You
certainly didn't see any oil droplets and you certainly didn't
smell it."
The scientists used complex instruments - including a special
underwater mass spectrometer - to detect the chemical signature of
the oil that spewed from the BP well after it ruptured April 20.
The equipment was carried into the deep by submersible devices.
With more than 57,000 of these measurements, the scientists
mapped a huge plume in late June when the well was still leaking.
The components of oil were de ected in a flow that measured more
than a mile wide and more than 650 feet from top to bottom.
Federal officials said there are signs that the plume has
started to break into smaller ones since the Woods Hole research
cruise ended. But scientists said that wouldn't lessen the overall
harm from the oil.
The oil is at depths of 3,000 to 4,000 feet, far below the
environment of the most popular Gulf fish like red snapper, tuna
and mackerel. But it is not harmless. These depths are where small
fish and crustaceans live. And one of the biggest migrations on
Earth involves small fish that go from deep water to more shallow
areas, taking nutrients from the ocean depths up to the large fish
and mammals.
Those smaller creatures could be harmed by going through the
oil, said Larry McKinney, director of Texas A&M University's Gulf
of Mexico research center in Corpus Christi.
Some aspects of that region are so little known tg t "we might
lose species that we don't know now exist," said Graham of the
Dauphin Island lab.
"This is a highly sensitive ecosystem," agreed Steve Murawski,
chief fisheries scientist for the federal agency NOAA. "The
animals down at 3,300 to 3,400 feet grow slowly." The oil not only
has toxic components but could cause genetic problems even at low
concentrations, he said.
Lubchenco said NOAA is "very concerned about the impact" of
the oil below the surface and federal officials last week started
more aggressive monitoring of it.
For much of the summer, the mere existence of underwater plumes
of oil was the subject of a debate that at times pitted outside
scientists against federal officials who downplayed the idea of
plumes of trapped oil. Now federal officials say as much as 42
million gallons of oil may be lurking below the surface in amounts
that are much smaller than the width of a human hair.
Whilesuederal officials prefer to describe the lurking oil as
"an ephemeral cloud," the Woods Hole scientists use the word
"plume" repeatedly.
The study conclusively shows that a plume exists, that it came
from the BP well and that it probably never got close to the
surface of the Gulf of Mexico, Camilli said. It is probably even
larger than 22 miles long, but scientists had to stop measuring
because of Hurricane Alex.
Earlier this week a University of South Florida team reported
oil in amounts that were toxic to critical plant plankton deep
underwater, but the crude was not necessarily in plumes. Those
findings have not been reviewed by other scientists or published.
The plume is probably still around, but moving west-southwest of
the BP well site at about 4 miles a day, Camilli said.
While praising the study that ended on June 28, Murawski said
more recent observations show that the cloud of oil has "broken
apart into a bunch of very small features, some them much farther
away." Texas A&M's McKinney said marine life can suffer harm
whether it is several smaller plumes or one giant one.
NOAA redirected much of its sampling for underwater oil after
consulting with Woods Hole researchers. The federal agency is now
using the techniques that the team pioneered with a robotic sub and
an underwater mass spectrometer, Murawski said.
Previous attempts to define the plume were "like watching the
Super Bowl on a 12-inch black-and-white TV and we try to bring to
the table a 36-inch HD TV," said Woods Hole scientist Chris Reddy.
The paper, fast-tracked for the world of peer-reviewed science, was
written on a boat while still in the Gulf, he said.
Reddy said he could not yet explain why the underwater plume
formed at that depth. But other experts point to three factors:
cold water, the way the oil spewed from the broken well, and the
use of massive amounts of dispersants to break up the oil before it
gets to the surface.
The decision to use 1.8 million gallons of dispersants amounted
to an environmental trade-off - it meant less oil tainting the
surface, where there is noticeable and productive life, but the
risk of longer-term problems down below.
Retired Coast Guard Adm. Thad Allen, the government's point man
on the Gulf oil spill, said it was a choice between two difficult
options - with the discussions going on in front of the president.
In the end, officials decided to "accept the implication of the
hydrocarbons in the water column rather than Barataria Bay or the
Chandeleur Islands" in Louisiana.
Given the slow rate at which the oil is degrading in the coldis ater, Samantha Joye of the University of Georgia, and others say
it is too early to even think about closing the books on the spill:
"The full environmental impacts of the spill will thus not be felt
for some time."


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