April 20 marks 10 years since the BP oil spill began off the Louisiana coast when the Deepwater Horizon drilling rig exploded. Over the next six months, more than 200 million gallons of crude spilled into the Gulf.
It's considered to be the largest oil spill in U.S. history.
Now while there are no more tar balls washing up on beaches from Texas to the Florida Panhandle, what about the lingering environmental effects of the disaster?
Steve Murawski is a fisheries biologist and marine ecologist at the University of South Florida College of Marine Science in St. Petersburg. He serves as Director of the Center for Integrated Analysis and Modeling of Gulf Ecosystems (C-IMAGE), which is funded by a grant from the Gulf of Mexico Research Initiative.
Over the decade since the Deepwater Horizon spill, thousands of scientists have analyzed its impact on the Gulf of Mexico. The spill affected many different parts of the Gulf, from coastal marshes to the deep sea.
On this week's Florida Matters, Murawski speaks to WUSF's Steve Newborn about the long-term effects of the spill. Here's part of their conversation:
Tell us about some of the surprises you’ve seen.
Originally, there was a steep decline in most species in the amount of oil in them. And then it popped back up in 2017 when we did our last comprehensive survey, and we think what's happening is the oil on the sea bottom is not being necessarily landfilled there, but it's re-suspended by passage of storms and underwater phenomenon that sort of like shaking up a snow globe, you know, that oil in the bottom keeps getting re-suspended and then basically entering the food chain.
So every time a hurricane comes zooming up the Gulf, we're going to have tarballs maybe, or some kind of effect on the ecosystem every time.
Yeah, we certainly will have tarballs for decades. And you see that when you see a hurricane and in Randolph, Louisiana, for example, we know that there's a lot of oil there at the toe of the beach, you know, just underneath and eventually that will get landfilled as well, but still we'll find deepwater tarballs for a long period of time.
One of the reasons why we're seeing a lot of oil on the bottom of the Gulf was the use of dispersants. This is a product with the name Corexit, it was injected at the wellhead site and it mixed with oil droplets either causing them to float in the water column or sink right down to the seabed floor like you were seeing. A lot of studies say that this dispersion could contain cancer-causing agents, toxins, endocrine-disrupting chemicals and mess with the fish's reproductive capabilities. What did you see differently from this spill from previous spills because of the use of dispersants?
This is probably one of the most controversial issues stemming from Deepwater and one that continues in terms of debate in the scientific community and then the Management Committee. The real interesting things that we're have worked on in the last 10 years is whether or not that made any difference at all.
One of the things that our group has done is create what we call “Deepwater Horizon in a Can,” which is basically a high-pressure facility in Hamburg, Germany. It is very clever, where engineers are basically able to inject the oil droplets with or without dispersants. But the key to all this was actually saturating the oil droplets with methane. That's the way it came out. And the good analogy is like a spray can, or maybe a champagne bottle when you open it, that champagne is infused with carbon dioxide, right? When you have a big pressure drop, like when you open the champagne bottle, it spews out all over the place, right?
We think that one of the major factors wasn't that it was used to disperse, but you created only small droplets by opening the champagne bottle. And we know that there's a huge pressure drop when that oil came out of the hole and that basically went into the seawater.
So the real question isn't so much how much we buried (on the sea floor) with the use of dispersants – it’s whether or not it actually was helpful at all, in those two primary objectives. And the scientific community is split on this. And what we need is either another field experiment where we can control this or a much larger experimental tank facility.
So I'm sure that the oil industry and the Coast Guard and others are going to think that that is the playbook for the next big subsurface blowout that happens. A lot of the scientists, including myself, are unconvinced that that actually is a method that actually does what it thinks it does.