Can ecotechnology cure the dead zone?

By Environmental News Network staff

The dead zone in the Gulf of Mexico has now grown to encompass more than 7,000 square miles.

Web Posted Monday, June 22, 1998
at 5:11 PM ET

The dead zone is caused by the nitrogen and other chemicals that flow into the Mississippi River watershed each spring and ultimately turn more than 7,000 square miles of the Gulf of Mexico into the equivalent of a watery wasteland. Think of an area roughly the size of New Jersey where nothing can grow.

The technical name for the condition -- hypoxia -- means the depletion of oxygen in a body of water. Nitrogen and other nutrients cause hypoxia, or as William Mitsch, professor of natural resources at Ohio State University and the leader of one of six federal task forces studying hypoxia says, "Hypoxia is the result of living in an over-fertilized society. We fertilize the living daylights out of the Midwest."

The main problem comes from farming. According to the U.S. Geological Survey, about 56 percent of the nitrogen entering the Gulf is from fertilizer runoff.

"It's hard for a farmer in the Midwest to connect his activities to problems in the Gulf of Mexico," Mitsch said. The Mississippi River watershed encompasses more than 40 percent of the United States, including Midwest farm fields.

Hypoxia happens when excess nutrients, such as nitrogen and phosphorus, accumulate in a body of water and cause algae to flourish into algal blooms. These blooms thrive on nitrates and phosphates and deplete the water of nearly all dissolved oxygen.

Mitsch's committee is responsible for developing ways to control the pollution that causes hypoxia in the gulf. At a meeting of the Ecological Society of America that took place in early June in St. Louis, Mitsch presented the committee's preliminary conclusions, and they concluded that employing the tools of ecotechnology is the way to go.

Ecotechnology essentially uses nature to take care of problems. The solutions proposed by the task force include restoring or building wetlands and riparian buffer zones along waterways.

"Ecotechnology establishes some degree of natural landscape between human activity and waterways," Mitsch said. Riparian zones, belts of vegetation next to a waterway, and wetlands both serve as filtering systems. Each essentially "cleans" runoff water of fertilizer by-products.

The Gulf of Mexico is not the only area affected by hypoxia. Algal blooms have turned up in the Baltic Sea, Chesapeake Bay and off the coasts of California and Florida.

Dissolved oxygen content in the Gulf of Mexico is normally 5 parts per million. Hypoxia occurs when this level dips to 2 ppm or lower. The lack of oxygen either forces aquatic life to relocate or kills it.

Other potential solutions suggested by the committee included:

• reducing the initial disposal of nutrients into waterways;
• increasing the ability of a watershed to assimilate nutrients
• changing the hydrology of the Mississippi Basin.

"It's our job to assess how well these proposed ecotechnologies will work in dealing with the hypoxia problem," Mitsch said. "It just makes ecological sense to try these kinds of things."

Copyright 1998, Environmental News Network, All Rights Reserved