JIM LEHRER: Now to the Gulf Coast, where the oil is no longer spewing.
We have two takes, the first about what's happening to the oil that's already in the water.
It's been 100 days since the Deepwater Horizon rig exploded, killing 11 workers, fouling the Gulf of Mexico, and leaving wildlife to an oily fate. A temporary cap on the gushing well finally halted the flow of crude two weeks ago, and now signs of oil on the surface have been greatly reduced as well.
As these images illustrate, at the end of June, crude covered thousands of square miles of the Gulf's waters. By this week, the remaining oil appeared only in small patches.
Mike Sutcliffe flew over the Gulf on Tuesday, sizing up the situation for BP.
MIKE SUTCLIFFE, oil observer, O'Brien's Response Management: At this point in time, going over the source, I actually didn't see any sheen whatsoever.
JIM LEHRER: But, in Louisiana, Plaquemines Parish President Billy Nungesser and others insist, it's far too early to relax.
BILLY NUNGESSER, president, Plaquemines Parish, Louisiana: Are they trying to say this is over? I mean, are they that stupid? It took six weeks from when it first started leaking to come ashore. And now they stopped it last week, so it's over?
JIM LEHRER: Before it was capped, the well spewed 94 million to 184 million gallons of oil, and coated more than 600 miles of coastline. BP's cleanup operation has skimmed about 35 million gallons of oily water and burned off another 11 million gallons.
An unknown amount remains suspended below the surface. And many marine scientists worry about that.
SAMANTHA JOYE, professor of Marine Sciences, University of Georgia: There's a lot of dispersed oil in the water, and that stuff could end up in the food web.
JIM LEHRER: In the meantime, entire communities that depend on fishing and tourism remain idled.
LUCIEN GUNTER, Acme Oyster House: Who would have thought that 100 days of an oil spill would, you know, really kind of put us in a situation that, after 100 years of business -- you know, we're worried about what's going on?
JIM LEHRER: BP announced today it has paid out more than $250 million in damage claims so far. The company also hopes to try a so-called static kill next week to plug the ruptured well once and for all.
Once the well is plugged, the newly named CEO of BP, Bob Dudley, vows the cleanup will go on as long as it takes.
JIM LEHRER: We get more now from Nancy Kinner. She's a professor and director of the Coastal Response Research Center at the University of New Hampshire. She's worked closely with the government since the oil spill in the Gulf.
JIM LEHRER: Dr. Kinner, Welcome.
NANCY KINNER, environmental engineer, Coastal Response Research Center Co-Director, University of New Hampshire: Great. Thank you.
JIM LEHRER: Where has all that oil gone?
NANCY KINNER: Well, it's weathered, basically. So, some of it evaporates. The kind of lighter molecules in there go up into the air.
And then what's left starts to be biodegraded by naturally occurring microorganisms. And then the remaining fractions stick together, and you get those kind of tarry substances. And then some of it is still under the water dissolved as droplets.
JIM LEHRER: Well, let's take some of these basic things. Do you agree that roughly 40 percent of the oil that was part of the spill is now gone?
NANCY KINNER: Yes. Just with evaporation alone, you can lose 35 percent or so of the oil that reaches the surface up into the air. So, yes, it's quite possible.
JIM LEHRER: And this is just a natural process?
NANCY KINNER: Yes. This is called weathering. It's a process that you see in all oil spills. And the key thing here is, in the Gulf, it's warmer temperatures, so it happens at a faster rate. So, you...
JIM LEHRER: Why? Why is that?
NANCY KINNER: For instance, if you're going to evaporate something, and it's a warm temperature, it evaporates, goes up into the air faster.
JIM LEHRER: Sure.
NANCY KINNER: Biodegradation by a breaking down of these molecules by the naturally occurring organisms, they work faster at warmer temperatures. So, all of those processes are accelerated.
JIM LEHRER: And does anything go up in the air as they're disintegrating?
NANCY KINNER: Yes. This -- these lighter fractions tend to evaporate, just like when you're at the gas station and you're pumping gas into your car, and you see those vapors. It's that kind of thing, I mean, not to that extent, but that is the kind of thing that happens.
JIM LEHRER: Is there an environmental problem there, a potential program, polluting the air?
NANCY KINNER: Yes, there is. Some of that will break down. As does any kind of release from combustion engines, you will see breakdown by -- the light rays from the sun help break it down, et cetera.
But EPA has been monitoring to see that those concentrations are at acceptable levels.
JIM LEHRER: Now, you -- when -- as one of the folks said in the setup piece, that there's no sheen anymore, that's -- that's a good thing, right?
NANCY KINNER: Right. Yes.
JIM LEHRER: And that -- you can see it with the naked eye, and -- but, for you, what does that mean?
NANCY KINNER: Well, basically, that's all part of that weathering process.
And the thing we have to remember is that, for 90-plus days, there was a major spill basically day after day after day.
JIM LEHRER: Sure.
NANCY KINNER: And now, a couple of weeks later, we haven't had that spill, and these natural processes have occurred and tried to catch up with the release.
JIM LEHRER: Now, the dispersants, these...
NANCY KINNER: Yes.
JIM LEHRER: ... chemicals that were put in, have they... are they still being used?
NANCY KINNER: No, they're not -- they're not being used, because you don't have the oil coming out of the well anymore. So -- and once the oil gets weathered, the dispersants don't work very well.
JIM LEHRER: All right, now, there have been reports that a lot of this oil sunk to the bottom. Is that true?
NANCY KINNER: I don't think we have all of the data in yet, but I think most of the data shows that the well -- oil came out of the well, and, when they added the dispersants there, the -- that broke the oil into little droplets. And that oil actually stayed under the surface, most of it, stayed under the surface. And then some fraction of it came up to the surface.
JIM LEHRER: So, what about the stuff that's still in there? Just a matter of time before it goes away on its own?
NANCY KINNER: Yes, what's happening is, again, a kind of a weathering process, but you don't have evaporation down there, because it's colder, and it can't go into the air.
NANCY KINNER: But biodegradation is occurring. And some of the data coming back from the cruises of the research vessels out there has shown that biodegradation is occurring out there right now. And, then, of course, there's just the natural dilution process.
JIM LEHRER: Is there any way to authoritatively predict what's going to happen and how long it's going take to get rid of the rest of this oil?
NANCY KINNER: I think we're going to have to keep monitoring, and we're going to have to really look at the organisms themselves to see what the effects...
JIM LEHRER: What exactly are these organisms that...
NANCY KINNER: The bacteria breaking it down?
JIM LEHRER: Yes. Yes.
NANCY KINNER: They're very, very tiny, tiny organisms.
And you can't see them with the naked eye.
JIM LEHRER: Oh, you can't see them?
NANCY KINNER: Oh, no, no...
JIM LEHRER: Oh, no. OK. OK.
NANCY KINNER: ... not the organisms that are breaking down the oil. They are really tiny.
And they basically live naturally in the ocean. And they are used to having some amount of hydrocarbons because the Gulf of Mexico has natural seeps of oil.
And, basically, what they do is, they use that oil, the compounds in the oil, as a food source. Just like we eat hamburgers, for example, and use oxygen to breathe into degrade it, they're using the organics in the oil and using oxygen from the water.
JIM LEHRER: Sure. Sure.
As an expert, are you optimistic about all of this at this point? I know about -- there's a whole -- the oil that is already onshore, that's a different thing.
NANCY KINNER: Right. Right.
JIM LEHRER: But the oil that's still in the water, what's your level of optimism that this is going to eventually go away and how long it might take?
NANCY KINNER: Well, I think it will -- it will weather, and we will lose a fairly large percentage of it to biodegradation.
JIM LEHRER: Yes.
NANCY KINNER: ... and, as I said, some to evaporation.
I think some of it, the heavier fractions, those kind of tarry fractions, will remain for a fairly long time.
JIM LEHRER: Like what, a matter of months, years?
NANCY KINNER: Oh, months -- months, at least, to years, yes.
And then what I don't think we know is what the effect will be on the organisms themselves. And we have really got to look into that.
JIM LEHRER: You mean what's left behind after the oil leaves?
NANCY KINNER: Right. Well, what they have come in contact with over that period of time, will it affect their genetic material, will it affect their metabolism, those kind of things. And those are longer studies.
JIM LEHRER: And the ecosystem within the water itself.
NANCY KINNER: That's right.
JIM LEHRER: Don't know yet?
NANCY KINNER: I think the book is still out on that.
JIM LEHRER: OK.
Dr. Kinner, thank you very much.
NANCY KINNER: Thank you.