Narrator: This is Science Today. Ecologist Alex Horne of the University of California, Berkeley builds wetlands. Usually, artificial wetlands are thought of as an effective low-tech way to treat sewage. They're especially useful in developing countries that can't afford so-called modern sewage treatment plants. But Horne and his fellow researchers have made an interesting discovery.

Horne: We have been able to stumble on the fact that things built like old-fashioned duck ponds, basically -- a bunch of reeds going out among water that's a couple of feet deep, and then some more reeds, some more water -- the kind of average wetland that most people think about, I think -- turns out to be an excellent way to remove nitrate from water. Now nitrate sounds like an innocuous compound.

Narrator: But in developing countries particularly, it's dangerous for small infants to drink water with high nitrate levels. The nitrate locks up the oxygen in their bloodstreams and slowly asphyxiates them.

Horne: The baby's actually unable to breathe well, and babies can die. So that's one good reason worldwide to keep nitrate levels low.

Narrator: And thanks to Horne's discovery, doing that will be a lot easier. For Science Today, I'm Steve Tokar.