(Translation is to come out later....XD)
來源網址：http://www.reuters.com/article/idUSTRE67N5CC20100824
Microbes ate BP oil deep-water plume: study
(Reuters) - A Manhattan-sized plume of oil spewed deep
into the Gulf of Mexico by BP's broken Macondo well has been
consumed by a newly discovered fast-eating species of microbes,
scientists reported on Tuesday.
The micro-organisms were apparently stimulated by the massive
oil spill that began in April, and they degraded the hydrocarbons
so efficiently that the plume is now undetectable, said Terry
Hazen of Lawrence Berkeley National Laboratory.
These so-called proteobacteria -- Hazen calls them "bugs" --
have adapted to the cold deep water where the big BP plume was
observed and are able to biodegrade hydrocarbons much more
quickly than expected, without significantly depleting oxygen
as most known oil-depleting bacteria do.
Oxygen is essential to the survival of commercially important
fish and shellfish; a seasonal low-oxygen "dead zone" forms
most summers in the Gulf of Mexico, caused by farm chemical
run-off that flows down the Mississippi River.
mHydrocarbons in the crude oil from the BP spill actually
stimulated the new microbes' ability to degrade them in cold
water, Hazen and his colleagues wrote in research published
on Tuesday in the journal Science.
In part, Hazen said, this is because these new "bugs" have
adjusted over millions of years to seek out any petroleum
they can find at the depths where they live, which coincides
with the depth of the previously observed plume, roughly
3000 feet. At that depth, water temperature is approximately
41 degrees F (5 degrees C).
FEASTING ON HYDROCARBONS
Long before humans drilled for oil, natural oil seeps in the
Gulf of Mexico have put out the equivalent of an Exxon Valdez
spill each year, Hazen said.
Another factor was the consistency of the oil that came from
the Macondo wellhead: light sweet Louisiana crude, an easily
digestible substance for bacteria, and it was dispersed into
tiny droplets, which also makes it more biodegradable.
These latest findings may initially seem to be at odds with
a study published last Thursday in Science by researchers
from Woods Hole Oceanographic Institution, which confirmed
the existence of the oil plume and said micro-organisms did
not seem to be biodegrading it very quickly.
However, Hazen and Rich Camilli of Woods Hole both said on
Tuesday that the studies complement each other.
The Woods Hole team used an autonomous robot submarine and
a mass spectrometer to detect the plume, but were forced
to leave the area in late June, when Hurricane Alex threatened.
At that time, they figured the plume was likely to remain for
some time.
But that was before the well was capped in mid-July. Hazen
said that within two weeks of the capping, the plume could
not be detected, but there was a phenomenon called marine
snow that indicated microbes had been feasting on hydrocarbons.
As of Tuesday, there was no sign of the plume, Hazen said.
That doesn't mean there is no oil left from the 4.9 million
barrels of crude that spilled into the Gulf after the April
20 blowout at BP's Deepwater Horizon rig. The U.S. government
estimated on August 4 that 50 percent of the BP oil is gone
from the Gulf and the rest is rapidly degrading.
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