Air Date: Week of August 27, 2004

Living on Earth’s Jennifer Chu reports that rising levels of carbon dioxide may be causing changes in the makeup of the Amazon.

Transcript

CURWOOD: Coming up: biomonitoring – a movement to help people find out how many PCB’s and other chemicals are in their bodies. First, this Note on Emerging Science from Jennifer Chu.

[SCIENCE NOTE THEME]

CHU: Anyone who lives near a hog farm will tell you the smell isn’t pretty. The source of that smell is large open pits filled with hog waste that’s been flushed out of hog houses. In recent years, many of these pits have been decommissioned. For instance, in North Carolina there are 1,700 inactive sites.

To clean up these pits, farmers have to drain the liquid and then truck the solid waste away for use as fertilizer. But farmers complain this process is very costly. Now, there may be a cheaper and greener solution to this disposal problem: poplar trees.

Researchers in North Carolina have taken a half-acre pit, drained out the liquid, filled the hole with soil and planted over 300 poplar trees. The roots of these trees grow faster and deeper than most others, and scientists have found they can absorb 3,000 gallons of sludge per acre per day. This sludge contains nutrients for the trees, such as nitrogen and phosphorus. The heavy metals in the waste, like copper and zinc, are stored in the trees’ tissue.

Researches believe the trees will act as a sponge and prevent these contaminants from leaking into groundwater. Hog farmers can opt to harvest the trees for lumber once the site is completely cleaned up. Scientists estimate that would take up to 15 years.

That’s this week’s Note on Emerging Science, I’m Jennifer Chu.

CURWOOD: And you're listening to Living on Earth.

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[MUSIC: The Pogues “A Pistol for Paddy Garcia” RUM, SODOMY & THE LASH (Wea International – 1985)]