September 11, 2012

Study Shows 200,000 Tons of Oil and Gas from Deepwater Spill Eaten by Bacteria

Researchers from the University of Rochester and Texas A&M University have found that over a period of five months following the disastrous 2010 Deepwater Horizon explosion and oil spill, naturally occurring bacteria that exist in the Gulf of Mexico consumed and removed at least 200,000 tons of oil and natural gas that spewed into the deep Gulf from the ruptured well head.

The researchers analyzed an extensive data set to determine not only how much oil and gas was eaten by bacteria, but also how the characteristics of this feast changed with time.

“A significant amount of the oil and gas that was released was retained within the ocean water more than one-half mile below the sea surface. It appears that the hydrocarbon-eating bacteria did a good job of removing the majority of the material that was retained in these layers,” said co-author John Kessler of the University of Rochester.

The results, published this week in Environmental Science and Technology, include the first measurements of how the rate at which the bacteria ate the oil and gas changed as this disaster progressed, information that is fundamental to understanding both this spill and predicting the behavior of future spills.

Kessler noted, “Interestingly, the oil and gas consumption rate was correlated with the addition of dispersants at the wellhead. While there is still much to learn about the appropriateness of using dispersants in a natural ecosystem, our results suggest it made the released hydrocarbons more available to the native Gulf of Mexico microorganisms.”

Workers cleaning beaches from the 2010 Gulf oil spill

Workers cleaning beaches from the 2010 Gulf oil spill

Their measurements show that the consumption of the oil and gas by bacteria in the deep Gulf had stopped by September 2010, five months after the Deepwater Horizon explosion.

“It is unclear if this indicates that this great feast was over by this time or if the microorganisms were simply taking a break before they start on dessert and coffee,” said Kessler. “Our results suggest that some (about 40 percent) of the released hydrocarbons that once populated these layers still remained in the Gulf post-September 2010, so food was available for the feast to continue at some later time. But the location of those substances and whether they were biochemically transformed is unknown.”

Previous studies of the Deepwater Horizon spill had shown that the oil and gas were trapped in underwater layers, or “plumes,” and that the bacteria had begun consuming the oil and gas. By using a more extensive data set, the researchers were able to measure just how many tons of hydrocarbons released from the spill had been removed in the deep Gulf waters. The team’s research suggests that the majority of what once composed these large underwater plumes of oil and gas was eaten by the bacteria.
Kessler, recently appointed as associate professor in the Department of Earth and Environmental Sciences at the University of Rochester, worked with graduate research assistant Mengran Du at Texas A&M to analyze more than 1,300 profiles of oxygen dissolved in the Gulf of Mexico water, spanning a period of four months and covering nearly 30,000 square miles.

The researchers calculated how many tons of oil and gas had been consumed and at what rate by first measuring how much oxygen had been removed from the ocean.

Du explained that “when bacteria consume oil and gas, they use up oxygen and release carbon dioxide, just as humans do when we breathe. When bacteria die and decompose, that uses up still more oxygen. Both these processes remove oxygen from the water.”

Du added that it is this lower oxygen level that the researchers could measure and use as an indicator of how much oil and gas had been removed by microorganisms and at what rate.

The work was supported by the National Science Foundation with additional contributions from the National Oceanic and Atmospheric Administration, the Sloan Foundation, BP/the Gulf of Mexico Research Initiative, and the Chinese Scholarship Council.

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About the University of Rochester
The University of Rochester is one of the nation’s leading private universities. Located in Rochester, N.Y., the university gives students exceptional opportunities for interdisciplinary study and close collaboration with faculty through its unique cluster-based curriculum. Its College, School of Arts and Sciences, and Hajim School of Engineering and Applied Sciences are complemented by its Eastman School of Music, Simon School of Business, Warner School of Education, Laboratory for Laser Energetics, School of Medicine and Dentistry, School of Nursing, Eastman Institute for Oral Health, and the Memorial Art Gallery.

About Research at Texas A&M University: As one of the world’s leading research institutions, Texas A&M is in the vanguard in making significant contributions to the storehouse of knowledge, including that of science and technology. Research conducted at Texas A&M represents an annual investment of more than $700 million. That research creates new knowledge that provides basic, fundamental and applied contributions resulting in many cases in economic benefits to the state, nation and world.

Media contact:  Leonor Sierra, University of Rochester, at (585) 275-4118 or lsierra@ur.rochester.edu or Karen Riedel, Texas A&M College of Geosciences, at (979) 845-0910 or kriedel@tamu.edu

 

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2 Comments to Study Shows 200,000 Tons of Oil and Gas from Deepwater Spill Eaten by Bacteria

  1. read a book many years ago about the sinkings of ships(oilers/tankers) during WW II by german subs,,Many gallons of fuel were sunk in the gulf and east coast..what”s the comparison with the amount of oil releases by the BP blow out ? Great story, incidentally,,going to forward to son for his radio broadcast…

  2. Charlie Rankin ' 50 on September 14th, 2012
  3. That’s good to know that the bacteria are breaking down some of the submerged oil, but it would be really great if there were some more recent samples. If 40% is still there after the first 5 months but the bacteria have stopped eating, that’s still thousands of gallons of oil that are present.

    It’s probably a bad sign that the bacteria used up enough oxygen that they had to stop feeding. If there’s not enough oxygen for bacteria to survive on the floor of the gulf, then what do you think happened all of the other marine creatures that lived down there?

  4. Isaac M on September 17th, 2012
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