Science Show

The Caribbean country of Trinidad and Tobago has a natural wonder of the world - a Pitch Lake. It's a basin of emulsified asphalt. Pauline Newman reports on efforts to study the area and the hope of discovering new forms of life.

Transcript

This transcript was typed from a recording of the program. The ABC cannot guarantee its complete accuracy because of the possibility of mishearing and occasional difficulty in identifying speakers.

Robyn Williams: The Caribbean country of Trinidad and Tobago has its own natural wonder of the world, Pitch Lake, a basin of emulsified asphalt beside the village of La Brea on the island of Trinidad. It's an incongruous sight; 95 acres of semi-solid black lake, surrounded by reeds and cashew nut trees. And it's quite a tourist attraction; 20,000 people a year visit, navigating the humps and sinks in the surrounding roads where veins of pitch from the deep oil-rich rocks that feed the lake force their way to the surface.

Pauline Newman: So even up on the hill as we were driving down we saw the pitch coming up underneath people's yards.

Lindsey Passey: That's right because it's going right in their yards themselves. The village of La Brea is said to be a village of pitch. Any part of the village that you go, you will see pitch. Everybody in this village really do believe that if they stop mining this Pitch Lake, let's say, 10, 15, 20 years, the whole thing will start coming right back up again until it reaches the level.

Robyn Williams: There are only a handful of sites in the world where asphalt rises from the depths and collects in pools on the surface, and Pitch Lake is the most important commercially. The pitch is exported all over the world to be turned into roads and insulating compounds. But until very recently no one suspected the pitch could harbour life, so no one ever looked. Now, however, astrobiologists interested in strange species that exist in unlikely places have discovered microbes growing in the asphalt. Pauline Newman is visiting Trinidad and exploring the unusual lake to see what the scientists are so very excited about.

Lindsey Passey: My name is Lindsey Passey, licensed tour guide at your service. Okay, come along. Are you ready for this?

Pauline Newman: To reach the Pitch Lake itself we had to cross one of the many clear rainwater-filled pockets and cracks that break the surface. Dragonflies swooped as we rolled up our trousers and waded through pink and purple water nymph lilies past tiny flitting fish.

Lindsey Passey: Honestly, my friends, doctors highly recommend this water for bathing purposes due to the sulphur contents into it. This water helps take care of all minor skin disease, pimples, mosquito bites, even a disease by the name of psoriasis. If you wish to take a bath, well, it's up to you.

Pauline Newman: Creamy yellow sulphur paste collects in patches and the lake can smell of rotten eggs. Its surface hisses and bubbles.

Lindsey Passey: Now, look at these areas here. These humps are really caused by natural gas, methane, forcing itself from the bottom to reach to the surface. You hear a sort of hissing sound when the pressure is very high. You strike a match over it you will see a flame of fire.

Pauline Newman: The Pitch Lake is thought to contain 10 million tonnes of asphalt. It oozes to the surface in patches where it spreads out and dries.

Lindsey Passey: This Pitch Lake was discovered by Sir Walter Raleigh in the year 1595. During that time of the year, my friends, the Pitch Lake was at the level of the road. After all the years they have been extracting pitch, that is what remains.

Pauline Newman: Enough to last another 400 years a present rate of extraction. The hotter the sun, the more liquid the pitch becomes and more dangerous.

Lindsey Passey: Within one week's time, honestly, the whole thing fills itself right back up again.

Pauline Newman: Birds and even cows searching for water in the dry season get stuck and sucked under. All in all, a site not exactly suited to life, you might think. But physicist Shirin Haque from the University of the West Indies in Trinidad thought otherwise. She leads an international team of astrobiologists who've recently started looking for living organisms in the pitch.

Shirin Haque: The interesting link is that it forms an analogue site for Titan, one of Saturn's moons where you have hydrocarbon lakes out there, and right here on planet Earth we have a natural hydrocarbon lake in the Pitch Lake. So using that type of analogy we are interested in what kind of organisms, microbes can survive in this kind of extreme condition.

Pauline Newman: Discovering life in the asphalt was a long shot, yet that's what Dr Haque and her colleagues seem to have found.

Shirin Haque: To date our samples have probably been about one foot deep into the Pitch Lake, and our initial results have shown the existence of microbes. We've done some deeper sampling where they have active mining, and even that has shown some. So these results need to be confirmed and repeated. But we have been sampling and running it through DNA sequencing as well as checking whether we have anaerobic or aerobic microbes existing there, which brings up as many questions as it might answer.

Paul Davies: It's a very, very basic problem.

Pauline Newman: Paul Davies is a fellow physicist and astrobiologist now at Arizona State University in the US. He was visiting the site.

Paul Davies: Are we just dealing with a surface phenomenon where biology has invaded and inhabited the surface of the pitch which has all sorts of chemical goodies lying around, or is there something going on at depth? Is there some subsurface biology of a form that might be very exotic?

Pauline Newman: Any surface biology would surely rely on oxygen, but oxygen won't be able to penetrate very far into the pitch, so if there is life beneath the surface it would have to get its energy by other means.

Paul Davies: The subsurface ecosystems that have been studied so far (for example, in deep aquifers) these make use of hydrogen as the ultimate source of metabolism and the hydrogen is produced either by radioactivity or by water passing over hot rocks. The question is whether in this sort of petrochemical Mecca that we see all around us here, whether there is a source of free hydrogen as well that subsurface micro-organisms could utilise.

Pauline Newman: And that's one of the things that Riad Hosein is looking for. Riad is Dr Haque's student.

Riad Hosein: I'm from the department of chemistry, I'm here to investigate the chemical basis for the biological phenomena that goes on in the Pitch Lake. And within 2008 we should get some very positive results, from what I've seen thus far.

Pauline Newman: At the very least the results will be interesting.

Paul Davies: It could be something totally unique because this is almost a unique setting in the world. I think it has been very little studied. There could be many, many surprises coming out of this place.

Pauline Newman: But as for the villagers of La Brea, whatever the scientists find, they'll continue to enjoy their oozing black lake as they have for generations.

So this I would imagine would be a wonderful playground for the village children. I guess they're not allowed here.

Lindsey Passey: Yes, yes, especially in the dry season when they come on here and play cricket or football or soccer. When there is a crisis of water within the village some of the villagers come down here to do their laundry, they spread it on the pitch, they go and bathe, and by the time they finish bathing their laundry is dry, they pull it up and they head for home. Living is very nice out on this Pitch Lake.

Robyn Williams: Lindsay Passey from the Trinidad village of La Brea ending that report from Pauline Newman.

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Guests

Pauline Newman
Hugh Downs School of Human Communication Arizona State University Arizona USA
http://www.asu.edu/clas/communication/people/faculty/davies/index.htm

Presenter

Robyn Williams

Producer

David Fisher

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