Earthsky Interviews
Private: The Dead Zone
11-27-2001 - Uncategorized
_DB:_ This season, scientists reported that the dead zone is the size of Massachusetts. They say that this hypoxic zone happens not because of too few nutrients, but too many. Nitrates and phosphates from agricultural fertilizers run off into rivers and are washed out to sea. These rich nutrients spur the growth of enormous algae blooms at the surface. The algae dies, then settles to the bottom to decompose. This process uses up the dissolved oxygen in the lower depths – and that leaves too little oxygen for most aquatic species to survive.
_JB:_ One solution, some researchers say, is wetlands – bogs, marshes, swamps and streamside forests. Wetlands filter out the chemicals that wash into waterways. Most of the nitrates turn into harmless nitrogen gas that floats away into the atmosphere. But to save the Gulf, we’d need millions more acres of wetlands in the Midwest and the lower Mississippi River basin. Two centuries ago, much of this area was swampy. Eighty percent of those natural wetlands are now gone.
_DB:_ Today’s program was made possible by the “National Fish and Wildlife Foundation”:http://www.nfwf.org/, in cooperation with the “U.S. Forest Service”:http://www.fs.fed.us/. We’re Block and Byrd for Earth and Sky.
The following individual(s) were interviewed for today’s show. Our thanks to:
Dr. William J. Mitsch
Director, Olentangy River Wetland Research Park
School of Natural Resources
The Ohio State University
Columbus, OH
Author’s Notes:
Restoring wetlands could be easy – you just break the drainage tiles that are under most of the farms of the Midwest. Instant wetlands!
In the Gulf’s hypoxic zone, dissolved oxygen levels dip below two parts per million, and most aquatic species can’t live in waters containing less than that. Dissolved oxygen levels in the Gulf are normally about 5 to 10 part per million.
The “dead zone” typically begins in the spring, when planting and fertilizing fields peaks. The accumulation of nitrogen and other chemicals usually reaches a maximum in midsummer and disappears in the fall.
It’s estimated that the American Midwest has lost about 80 percent of its wetlands in the last two centuries, compared to a 50 percent loss in the contiguous United States. Under current conservation programs, about 577,000 acres of wetlands have already been created or restored. So about 10 to 25 times more wetlands are needed to cause a significant reduction of nitrogen levels in the Gulf, says Dr. William Mitsch of Ohio State
University.
Ohio has lost ninety percent of its wetlands.