Deepwater Horizon Oil Spill Residue Still Present 10 Years Later

Traces of weathered crude oil from the Deepwater Horizon oil spill were still present in Louisiana’s shoreline environments a decade after the disaster, according to a new study.

The oil rig in the Gulf of Mexico exploded and sank 40 miles off the coast of Louisiana in 2010. Eleven people were killed and over the next 87 days, 4 million barrels of oil leaked from the Deepwater Horizon. It was the largest spill in the history of marine oil drilling operations, according to the U.S. Environmental Protection Agency.

Scientists have been studying the spill ever since. One group of researchers tracked crude oil residue from the Deepwater Horizon for 10 years. In a paper published Tuesday in the journal Frontiers in Marine Science, the team describes the chemical components and changes – or weathering – of the oil in the environment.

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“The better we understand the chemicals and their chemical reactive properties as well as their physical properties, the better we will be able to mitigate oil spills and understand and detect environmental damages from oil spills,” lead author Edward Overton, a professor in environmental sciences at Louisiana State University, said in a news release.

Overton and his team found that 30% to 40% of the oil evaporated into the air. Water soluble chemicals in the oil dissolved quickly, and large portions of the spill were also degraded by the sun and microbes.

“Oil spills release lots of chemicals quickly and most damage from oil spills occurs fairly soon after the spill,” Overton said.

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The research also notes that the chemically altered and longer persisting oil residue can have its own environmental impacts.

“Oil spills are acute events, having potential for causing environmental impacts in the air, on the water’s surface, in the water column and bottom sediments, and in organisms inhabiting these impacted areas,” the paper reads. “However, as oil weathers, the residue become resistant to further rapid compositional changes, and this means that, if not removed by response personnel, residue can remain in environments for extended time, causing long term disruptions of impacted areas.”

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But, the researchers note, the extent of chemical changes to oil after a spill depends largely on weather and local conditions.

“Environmental circumstances surrounding specific spills greatly affect how quickly the compounds can react, what they cover or coat and how much oxygen can be taken up in critical habitats,” Overton said.

The goal of the research, he said, was to expand the understanding of the types of chemicals found in oil and how they might impact the environment.

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