by Neil Caudle

hen Chris Martens has climbed to the top of the tower, more than 200 feet in the air, having hugged the rough Zs of its metal so tight that his arms are now scratched up and raw, he can stop and gaze down on the deep, pillowed green of the forest. He can watch the macaws, bright as feathered candy, cruising the moist, rising air.

For a marine scientist who grew up with boats, whose preferred elevation is sea level or below, whose wife introduces him as the "mud man" because he spends so much time down and dirty in coastal sediments, this is an unthinkable height. What is he doing here, aloft in the wilds of Brazil, with only a smattering of Portuguese, with some gadgets wired inside of cooking pots like homemade bombs? He has come here to measure the breath of the forest.

What the rain forest breathes is a matter of interest because the fate of the Amazonian rain forest may be entwined with the fate of the Earth. Do rain forests protect us from global warming by producing oxygen and consuming greenhouse gases such as methane and carbon dioxide? Or does a rain forest’s decaying litter actually produce more greenhouse gas than the forest consumes?

No one knows. So as pressure mounts on rain forest nations to protect and preserve the "lungs of the Earth," those nations are in the political bind of trying to limit mainstays of their economies—logging and ranching—without hard evidence that restrictions will do any good.

To try and resolve the scientific uncertainties, Brazilian and U.S. scientists in the mid-1990s proposed a comprehensive study of Amazonia, including greenhouse-gas exchange and the effects of land-use changes in the rain forest. The response was a multinational project known as the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), led by Brazil, with U.S. participation, and funded by NASA.

hen word of this project reached Christopher Martens, professor of marine sciences, his first thought was radon. Yes, this was odd. Radon is not a factor in the greenhouse effect or global warming. It is a short-lived radioactive gas that can escape from the soil and build up to risky levels in basements and crawl spaces.

But Martens knew that radon had a useful side, as well. At sites in Quebec, Alaska, and North Carolina, Martens and his students had for years used radon as a "tracer." While gases such as carbon dioxide and methane mix and merge with the elements around them, radon retains its identity—a reliable marker that goes with the flow.

"Radon has no chemistry or biology," Martens explains. "Only physical processes affect it. When it comes in from a source, it either decays away, radioactively, or it leaves, physically, and so it’s a perfect tracer for studying the physics of gas exchange."

Next: "We have to be clever."

© 2001 Endeavors, The University of North Carolina at Chapel Hill. All rights reserved.