Constant pushes from the Mississippi River ensured that the bulk of the oil slick produced in the Gulf of Mexico by the BP/Deepwater Horizon oil spill did not reach more coastlines than it did. In other words, the river limited the extent of the devastation that may have occurred.
Scientists were expecting the coast of Louisiana to be extremely affected by the spill. However, their predictions did not take into account the influence the large river had on this region of the Gulf. The waters kept most of the hydrocarbons away.
The BP oil spill began in late April, 2010, when the Deepwater Horizon drilling rig exploded, and then sunk two days later. A ruptured wellhead could not be covered in time, and released massive amounts of crude from the ocean floor.
Underwater plumes of oil spread throughout the Gulf, forcing the National Oceanic and Atmospheric Administration (NOAA) to shut down vast areas to commercial fishing. The total value of damages rose to billions of dollars.
University of Pennsylvania expert Douglas Jerolmack worked with two other scientists to reach this conclusion. They say that the river produced plumes of freshwater that struck against the oil slicks, pushing them away from the coasts.
“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,” says Jerolmack.
“Surprisingly no one had really investigated the effect that the tilting of the water surface can have on the migration of oil,” the expert goes on to say. Details of the work were published in the latest issue of the peer-reviewed scientific journal PLoS ONE, which is edited by the Public Library of Science.
An additional reason why existing models could not predict the motion of oil plumes accurately was that they were originally developed to assess the movements of water. Oil has a different density, and is therefore affected differently by underwater currents.
People, animals and plants living on the Louisiana coastline were lucky that the oil spill coincided with a typical spring flood on the Mississippi River. This extra punch further contributed to pushing most of the oil away from beaches and other sensitive habitats.
Funds for the research were provided by the US National Science Foundation (NSF).
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