BP’s Deepwater Horizon oil spill may have been much larger than thought

NEW ORLEANS -- Oil from the 2010 BP Deepwater Horizon disaster may have spread much farther than initially thought, possibly reaching as far as Texas and the Florida Keys, a new study suggests.

"The impact of the oil's toxicity is larger than previously assumed," said Igal Berenshtein, a University of Miami marine scientist and the study's lead author. "It's important to account for the toxicity that's invisible and also the three-dimensional nature of the (oil) plume, and our study does that."

He estimates the extent may be 30% larger than 2010 satellite imagery indicated. The imagery was widely accepted by the public and scientists as showing the spill's reach, but a growing body of field data collected just after the spill indicates the oil had a much larger footprint.

Berenshtein and the study's other scientists combined data from water, seafloor and beach sampling, fish toxicity studies and oil transport models to track oil invisible to satellites.

It's been nearly 10 years since the Deepwater Horizon rig drilling BP's Macondo well blew up, causing an 87-day uncontrolled release of more than 160 million gallons of oil into the Gulf of Mexico. Eleven people were killed in the explosion.

The spill killed or sickened an incalculable number of marine animals and is blamed for lingering health problems in hundreds of spill responders and coastal residents.

Published this week in the journal Science, Berenshtein’s study stresses the need for a more thorough method of assessing the impact of future spills. It says satellite imagery only shows the oil that’s visible from space, and often overlooks thinner concentrations that are also harmful to the environment. Also missing from satellite assessments is the three-dimensional quality of oil spills, including large plumes below the water’s surface.

Study co-author and University of Miami oceanographer Claire Paris said satellites still have value for assessing spills.

"Currently, satellites provide the most rapid and accurate indication of the location of the oil slicks," she said. "But the oil spill also extends in the water column."

To understand the full ecological impact, site sampling and oil movement modeling, which incorporates information about currents and weather patterns, should be incorporated after the next large spill, the authors wrote.