Scientists Find Where 84 Million Gallons of Oil From the Deepwater Horizon Disaster Went

Researchers discover that a ‘dirty blizzard’ of petroleum oil rained down on the ocean floor—and fragile corals.

(Photo: Reuters)

Oct 29, 2014· 1 MIN READ
Todd Woody is TakePart's editorial director, environment.

When the Deepwater Horizon drilling rig exploded in April 2010, more than 200 million gallons of oil gushed from BP’s Macondo well into the Gulf of Mexico. Much of the petroleum from the United States’ largest oil spill ended up near the surface of the ocean or washed ashore. But the final destination of 84 million gallons has remained a mystery.

Until now.

A team of scientists led by David Valentine, a University of California, Santa Barbara, earth science professor, have discovered that the oil eventually fell to the deep ocean floor in a “dirty blizzard” that covered a 1,250-square-mile area.

That could have significant implications for the health of coral reefs in the Gulf—and BP’s ultimate liability for the environmental damage caused by Deepwater Horizon. Since the disaster, a battle has raged between BP and some scientists over whether the oil spill harmed deep-sea corals that provide habitat for a plethora of marine life.

Valentine’s study, published in the Proceedings of the National Academy of Sciences of the United States on Monday, concluded that corals were in the path of the oil spill.

“Our analyses indicate that significant quantities of Macondo oil were transported near the corals before or during fallout to the sediment,” the study states.

Valentine and colleagues from the Woods Hole Oceanographic Institute and the University of California, Irvine, also said the oil contamination could reduce the number and diversity of tiny marine organisms that live on the ocean floor within the “bathtub ring” of oil.

A BP spokesman, Jason Ryan, dismissed the finding. “The authors failed to identify the source of the oil, leading them to grossly overstate the amount of residual Macondo oil on the seafloor and the geographic area in which it is found,” he told The Associated Press.

So how did the scientists discover where the missing oil went?

Any oil from the explosion would have long since been degraded. But a hydrocarbon called a hopane doesn’t decay, and Valentine and his colleagues used it as a proxy for the BP oil so they could trace its dispersal after the explosion.

During the course of a dozen expeditions to the Gulf, they collected more than 3,000 sediment samples from the seabed at 534 locations.

The sediment that contained the highest concentrations of hopane were within 25 miles of the Macondo well.

“Based on the evidence, our findings suggest that these deposits come from Macondo oil that was first suspended in the deep ocean and then settled to the seafloor without ever reaching the ocean surface,” Valentine said in a statement.

“These findings should be useful for assessing the damage caused by the Deepwater Horizon spill as well as planning future studies to further define the extent and nature of the contamination,” he added.