Agriculture tied to gulf 'dead zone'

April 28, 2011 at 5:58 PM

CHAMPAIGN, Ill., April 28 (UPI) -- The spring rains drenching the U.S. Midwest may lead to an eventual environmental problem of oxygen "dead zones" in the Gulf of Mexico, researchers say.

Researchers at the University of Illinois and Cornell University warn that phosphorus and nitrate pollution in the Mississippi River from agricultural runoff is causing a growing hypoxic zone in the Gulf of Mexico that threatens marine life and wildlife habitats.

The hypoxic zone, which forms every spring or summer in the gulf, measured 7,000 square miles last summer and with high flow in the Mississippi from heavy spring rains, the zone may be large again this summer, a UI release said Wednesday.

Researchers said the farm fields in the Corn Belt -- spanning Illinois, Indiana, Iowa, Ohio and southwest Minnesota -- and in southeastern Missouri and northeastern Arkansas, are the largest contributors of nitrate and phosphorus pollution to rivers, lakes and streams that empty into the Mississippi River and, ultimately, the Gulf of Mexico.

"This illustrates the complexity of the problem, as we have created an agricultural system with high yields, but one that is leaky with nutrients," UI biogeochemist Mark David said. "Although we lose very little phosphorus in terms of how much we apply in fertilizer, it takes only a small amount to cause a water quality problem."

The U.S. Environmental Protection Agency has urged state agencies to work to reduce concentrations of nitrogen and phosphorus in the water supply and improve water quality, he said.

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