USA: Study shows Chemical plume detected in oil spill area in the Gulf of Mexico

Record ID: 343584

  • Title: USA: Study shows Chemical plume detected in oil spill area in the Gulf of Mexico
  • Date: 20th August 2010
  • Summary: GULF OF MEXICO, UNITED STATES (FILE) (REUTERS) VARIOUS OF HEAVILY OILED BIRD IN WATER VARIOUS OF BIRDS VARIOUS OF OILED WATER
  • Embargoed: 4th September 2010 13:00
  • Keywords:
  • Location: Usa
  • Country: USA
  • Topics: Nature / Environment
  • Reuters ID: LVA58JBEL0TROXSHYOVYIFJM375I
  • Story Text: A 22-mile-long chemical plume from the Deepwater Horizon oil spill has been detected 3,000 feet below the ocean surface in the Gulf of Mexico.
    The discovery, made by a robot submersible, shows that even deep sea ecosystems have not escaped the disaster.
    Scientists still cannot say what the long-term effects will be.
    The plume, containing a cocktail of petroleum hydrocarbons, is more than a mile wide and rises 650 feet above the ocean floor.
    In June researchers tracked it moving slowly south-west of the source of the BP blowout at around 0.17 miles per hour.
    Analysis of its composition confirmed that the plume was not the result of a natural oil seep.
    Oxygen readings suggest that bacteria are not breaking down the chemicals as quickly as expected.
    Geochemist Dr Benjamin Van Mooy, a member of the US research team from Woods Hole Oceanographic Institution (WHOI) in Massachusetts, whose findings were published Thursday (August 19) in the journal Science, said: "The overall result is that we didn't see market oxygen drawdown in this plume location near the well."
    Until now, attempts to detect and measure any deep sea plumes from the spill have been inconclusive.
    The new study employed an autonomous underwater vehicle (AUV) called Sentry which detected the plume and zig-zagged through it on a 10-day reconnaissance mission.
    Bristling with sophisticated instruments, the submersible recorded information about chemical compounds and biological activity at various depths.
    Unlike polluted surface water, samples taken from the plume were clear and had no oil odour. However, this does not mean it is not harmful to the environment, the scientists point out.
    It will take months of further work to identify the full list of chemicals in the plume.
    "All I can tell you is that we found a plume. And I can't tell you how much oil is in it because we don't have the values yet. We know there is a plume. We know its length. We know its shape. We know that we collected water samples in it. And when we have analyzed those samples we will be able to constrain how much - what the inventory of those compounds are in there. And at that point, we may be able to see whether its a penny in a very big checkbook, I mean a checking account, or maybe it's bigger," WHOI marine geochemist Dr Christopher Reddy said.
    A key discovery was that, contrary to previous predictions, the scientists found no "dead zones" within the plume - regions of oxygen depletion where almost no fish or other marine animals can survive.
    Although this may sound like good news, it means bacteria are not consuming the chemicals at the expected rate, allowing the plume to persist for a long time.
    BP's Deepwater Horizon offshore rig was drilling into the sea bed 5,000 feet beneath the Gulf of Mexico when the blowout occurred on April 20, sending an uncontrolled surge of oil and gas to the surface.
    The resulting explosion and fire killed 11 crew and created a massive oil spill, described as the worst environmental disaster in US history.
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