There's Less To See, But Oil Still Haunts The Gulf

Now that the oil stopped spewing from sea floor, we see less of it on the Gulf's surface. It's dispersed. But what does that mean and how does that affect life in the Gulf? Host Liane Hansen talks with oceanography professor Ian MacDonald and Richard Snyder, director of the Center for Environmental Diagnostics and Bioremediation, about their research.

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LIANE HANSEN, host:

This is WEEKEND EDITION from NPR News. Im Liane Hansen.

There's more criticism surrounding the Gulf oil spill this morning. A congressional investigation has found that the Coast Guard routinely allowed BP to dump thousands of gallons of dispersant into the Gulf of Mexico, even though the federal government had directed limited use of the toxic chemical that breaks up the oil.

Coming up, how BP has changed its strategy to address the mounting damage to the company's image. First: Now that that the oil has stopped gushing from the Gulf floor, we're not seeing much on the surface. Where did it go?

For answers, we turn to Ian MacDonald. We spoke to the professor of oceanography at Florida State University in June. He joins us once again from member station WFSU in Tallahassee. Welcome back.

Professional IAN MACDONALD (Oceanography Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee): Hello, Liane. Good to be here.

HANSEN: Also with us is Professor Richard Snyder, director of the Center for Environmental Diagnostics and Bioremediation. He's in the studios of member station WUWF in Pensacola, Florida. Thank you for joining us.

Professor RICHARD SNYDER (Director, Center for Environmental Diagnostics and Bioremediation): Oh, hello, Liane. How are you?

HANSEN: Well, thank you.

Professor MacDonald, I want to start with you. Has all of the oil been dispersed, and what exactly does that mean?

Prof. MACDONALD: Well, there's not any new oil flowing into the Gulf, and thats good news. And oil floating on the water in the Gulf in summertime conditions, if it's a light crude, has a half-life of between seven to five days, and we're going on 15 days-plus since they shut off the well. So we should be down to a quarter or even an eighth of the volume that was there originally.

The oil goes away. It dissipates into the atmosphere. It coagulates. It sinks. It dissolves into the water column. It doesnt disappear. It's still there; we just dont see it in the great surface layers that we had before.

HANSEN: Hmm. Professor Snyder, what are you seeing in your research on where the oil has gone?

Prof. SNYDER: On the microscopic level, there has not been enough done yet to document what is happening out there with all the use of this dispersant. So we are taking water samples, extracting them, and looking for the molecules of the oil that come ashore. Mostly, thats been floating oil that has gotten to the beaches and gotten entrained into the beach sand. It's gotten buried into the beach sand. So thats really what we're dealing with now, is the aftereffects of the floating oil that - have come ashore.

HANSEN: Professor MacDonald, what are you seeing that's apparent to the eye? What are you looking at on the microscopic level?

Prof. MACDONALD: Apparent to the eye are the floating masses that are left, that are remaining. And these are big, gooey blobs of tar balls and mats of emulsified oil. And they're still present; they're still drifting around, and they still will make landfall.

Whats not apparent is the oil thats buried into the marine sediments, into the marine soils. And as Dick was implying, the material that has come ashore, or has sunk to the bottom, is buried. And what it does is, it degrades as long as there's oxygen present in the soil. But as soon as it reaches a level where there's no oxygen, then it persists - and it persists for decades.

And so that - the chemical residuum of that, and the chemical material released by that persistent oil will affect the animals that live in the soils, in the sands. And unfortunately, they're the base of a lot of the marine food chain.

HANSEN: Professor Snyder, could you actually tell us about - what are marine soils?

Prof. SNYDER: When we talk about marine soils, we use the term sediments rather than soil. Soils are more ascribed to terrestrial habitats. And when we look at sediments - for example, when we go due south of Pensacola, out over the continental shelf, as we move out over that shelf - we see quartz sands close into the shore and gradually more calcium carbonate, as there's less sand transport and more biological activity making that calcium carbonate.

And then when you drop down off of the slope and get into the deepwater, there's very little terrestrial quartz, sands and terrestrial sediment that makes it out that far. And you start getting very, very fine, silty clay, muds. And you get out into the deep waters, they're even described as oozes sometimes, because it is that very, very fine mud consistency.

So the marine sediments change quite a bit, depending on where you are.

HANSEN: Right. And oil could be a problem in all of those instances.

Prof. SNYDER: Yes, it could.

Prof. MACDONALD: Because they're all living sediments, because they all contain burrowing organisms and complex chemical reactions, which are greatly affected by the presence of high organic loads like will be yielded from these oil droplets that fall.

HANSEN: Something I'd like to ask both of you - and Ill start with you, Professor Snyder. What questions are you asking as - moving forward, and what hidden impacts are you looking at?

Prof. SNYDER: We dont know what the concentrations of the oil are. We dont know the degradation rates by the bacteria of the soil, and that will be temperature-dependent. If it's in deep cold water, it will not degrade as fast as it will in the surface water. We dont know if it's being degraded faster than it's moving, or if it's going to get to the shoreline in concentrations that will have toxic effects.

We have fish populations on natural and artificial reefs all over the continental shelf south of Pensacola. Those could all be impacted by dissolved oil plumes that come up onto the shelf. And is there enough toxicity in the remaining, dissolved oil to have serious impacts to our local fisheries and wildlife?

HANSEN: Professor MacDonald, what questions are you asking? What hidden impacts are you looking at?

Prof. MACDONALD: The question is: Will the Gulf of Mexico, as a result of this, be a less productive ecosystem? And if the productivity and the biodiversity were to be diminished by a few percentage - 10 percent, 15 percent - that might be very hard to document. Nonetheless, this would be an effect. And if you stretched it out over several years, it would be a severe effect on the ecosystem and the well-being of the people that depend on this ecosystem.

Here's an idea. BP is going to be hit with a huge fine. This fine should be put in a permanent trust to assess, to understand, and to sustain the Gulf of Mexico ecosystem for the future generations. I hope that will happen.

Prof. SNYDER: We have a concept of ecosystem, or environmental or ecological resilience. And that is, you can beat something up and at some point, it won't get up again. Have we done that with this oil spill? Thats a question that we won't know for years to come because a lot of those impacts will cascade into the future. Some will be synergistic with other impacts, like overfishing.

A really good example of this is the Georges Bank Fishery, where we've fished cod almost to extinction. And having backed off on the fishery pressure, those stocks are not responding. We've exceeded some level of resilience there. Have we done that to the Gulf of Mexico? I think thats the big, big, overriding question that, as Ian says, we need sustained funding for a long period time to make sure that that - to find out whether that is happening or not.

HANSEN: Richard Snyder is director of the Center for Environmental Diagnostics and Bioremediation. Ian MacDonald is a professor of oceanography at Florida State University. Thank you both.

Prof. SNYDER: Thank you, Liane.

Prof. MACDONALD: Thank you, Liane.

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