Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Push From the Mississippi Kept Deepwater Horizon Oil Slick Off Shore, Penn Research Shows

11.05.2012
When the Deepwater Horizon drilling rig exploded April 20, 2010, residents feared that their Gulf of Mexico shores would be inundated with oil. And while many wetland habitats and wildlife were oiled during the three-month leak, the environmental damage to coastal Louisiana was less than many expected, in part because much of the crude never made it to the coast.
Research by a trio of geoscientists, including the University of Pennsylvania’s Douglas Jerolmack, now offers an explanation for why some of the oil stayed out at sea. Using publicly available datasets, their study reveals that the force of the Mississippi River emptying into the Gulf of Mexico created mounds of freshwater which pushed the oil slick off shore.

“The idea is that, if the water surface is tilting a little bit, then maybe the oil will move downhill, sort of like a ball on a plate. If you tilt the plate, the ball will roll one way and then another,” Jerolmack said. “Surprisingly no one had really investigated the effect that the tilting of the water surface can have on the migration of oil.”

The finding, published in the journal PLoS ONE, could help make better predictions about where oil will make landfall in future oil spills, helping to direct efforts to spare fragile coastlines and wildlife.

Jerolmack, an assistant professor in Penn’s Department of Earth and Environmental Science, collaborated on the study with lead author Federico Falcini, a postdoctoral investigator in Jerolmack’s lab at the time. Bruno Buongiorno Nardelli of Italy’s Consiglio Nazionale delle Richerche also contributed to the work.

As the Deepwater Horizon disaster unfolded two years ago, the National Oceanic and Atmospheric Administration used information from satellite data and helicopter flights over the Gulf to produce aerial images of the shifting coat of oil. NOAA also issued daily forecasts of where the oil slick might travel, using computer models based on ocean currents.

“We noticed that there was a big disconnect between the forecasts of where the oil was going to be the next day and where the oil actually was the next day,” Jerolmack said. “That maybe shouldn’t be a surprise, because these computer models were not generated to forecast the movement of oil, they were generated to forecast the movement of water.”

Clearly some force beyond the ocean’s current was acting to direct the oil’s movement. So the researchers turned their attention to the ocean’s topography.

They accessed interpreted data from the Colorado Center for Astrodynamics Research that provides real-time information about sea-surface levels. These measurements, gathered from radar bounced off the surface of the ocean from the Jason2 satellite, were considered unreliable near shore, where land could confuse the signals.

The researchers performed their own analyses on the Jason2's raw data to separate out this confounding effect and glean sea-surface-level information within a few kilometers of shore. Their results confirmed the existence of several mounds and troughs in the Gulf. One mound in particular drew their attention.

“We recognized that there was a very persistent mound, a bump or a bulge, in the elevation of the sea surface in the vicinity of the Mississippi Delta,” Jerolmack said.

The reason was that the oil spill coincided with the typical spring flood on the Mississippi, creating a larger-than-normal flow of water into the Delta. This powerful discharge of fresh water mounded on top of the denser salt water of the Gulf. The resulting bulge, which was approximately 10 centimeters higher than the surrounding ocean and 50-100 kilometers in diameter, was positioned so that oil from the Deepwater Horizon drilling rig ran “downhill” and away from the coast.

A mathematical model representing a two-layer fluid — comprised of oil on top and fresh water underneath — confirmed that the slope of the mound was sufficient to direct the oil’s movement.

“The model was able to predict the speed at which the oil moved away from this fresh-water mound and how long it took for the oil to move away from the mound,” Jerolmack said.

Despite this correlation, mound formation was just one of many competing forces driving the drift of the Gulf oil slick, Jerolmack noted.

“A mound can only form if the river discharge is relatively high and the ocean is relatively calm.”

Indeed, as the Mississippi flood waters subsided and the river’s discharge lessened, the bulge disappeared and the oil slick moved back toward shore. The winds of Hurricane Alex, which formed in late June 2010, also resulted in a decline in mound formation and the oil slick being pushed toward land.

Still, factoring in mound formation will help produce more accurate forecasts of oil spills around the Mississippi Delta — and perhaps predict other dispersion events as well.

“This feature is likely important not only for the oil spill, but also for the dispersal of nutrients, sediments and pollution into the Gulf,” Jerolmack said.

The study was supported by a grant from the National Science Foundation.

Katherine Unger Baillie | EurekAlert!
Further information:
http://www.upenn.edu

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

Im Focus: Artificial Enzymes for Hydrogen Conversion

Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.

Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

New quantum phenomena in graphene superlattices

19.09.2017 | Physics and Astronomy

A simple additive to improve film quality

19.09.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>