A new study says oil from the Deepwater Horizon disaster is still trapped in Alabama's beaches four years later.
The report was released recently by Auburn University researchers who've been studying the BP oil spill since shortly after it occurred.
A team from Auburn collected oil on Alabama's coast as recently as August. The research found that oil is still trapped in the sand, mostly as tar balls.
Test results also show the oil degrades much slower when it's submerged than when it's exposed to air or water.
The report says the latest findings and other research show that oil could remain an ecological threat for years.
The Deepwater Horizon rig exploded in April 2010, killing 11 workers and spewing millions of gallons into the Gulf of Mexico.