Corn's gulf impact

Addressing environmental problems always seems to involve trade-offs. For the pursuit of ethanol, here's another potential gotcha: expanding the size of the Gulf of Mexico's annual "dead zone."

Scientists at the University of British Columbia and the University of Wisconsin looked at the energy bill President Bush signed in December and its goal of producing 36 billion gallons of ethanol a year by 2022. They analyzed the impact it could have on nutrients from farm runoff. Nutrients in the runoff flow down the Mississippi and Atchafalaya Rivers and feed algae in the Gulf. When the algae die, they decompose, which uses up oxygen in the water. Low-oxygen waters are fatal to organisms like shellfish.

If the US meets its ethanol goals without reducing other demand for corn, the amount of nutrients flowing into the Gulf of Mexico could rise from 10 to 34 percent above today's level. The results of the study appear in the current issue of the Proceedings of the National Academy of Sciences.