Long after the Deepwater Horizon oil spill, the marshy shores of the Gulf of Mexico were still feeling the effects of the disaster. Marsh grass retained plant-smothering oil, and the soil continued to crumble away at a faster rate than before the spill, causing the shoreline to retreat more rapidly than it would otherwise, a new study shows.
Following an explosion in April 2010, the Deepwater Horizon rig pumped nearly 800 million liters of oil into the sea (SN: 2/12/20). The disaster killed dozens of humans and untold sea life. And the oil and its by-products were catastrophic for the Gulf ecosystem, both underwater and along the shore (SN: 4/3/15).
But the oil also caused structural damage to the shoreline by killing the marsh plants crucial to holding soil in place, researchers report January 25 in Environmental Pollution. That’s making the coast more vulnerable to tropical storms that may be increasing in intensity due to climate change.
“If the plants are compromised in any way, shape or form, you’re going to lose a lot of land,” says Giovanna McClenachan, an ecologist at Nicholls State University in Thibodaux, La.
McClenachan was working on her Ph.D. at Louisiana State University in Baton Rouge when the disaster happened. She and her supervisor, coastal ecologist Eugene Turner quickly set up research plots in the marshy coast of south Louisiana. Three times a year for the next eight years, they conducted tests on the soil strength with a sheer vane, a common tool farmers use to test soil strength, and analyzed the amount of oil it contained.
They also examined satellite images from 1998 to 2021 to analyze what marsh vegetation looked like before, during and after the spill over a much longer 23-year period.
The field test revealed that, immediately after the Deepwater Horizon disaster, the oil concentration of some of the most volatile components of oil, called aromatics, in marsh soil jumped from an average of 23.9…
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