June 2008

U.S. Water News Online

NEW ORLEANS — Researchers predict a "dead zone" of oxygen-depleted waters off the Louisiana and Texas could grow this summer to 10,084 square miles, making it the largest such expanse in at least 23 years.

If the preliminary forecast holds, the researchers say, the size of the so-called "dead zone" would be 17-21 percent larger than at anytime since the mapping began in 1985 — and about as large as the state of Massachusetts. Another forecast is planned next month.

The report from scientists at Louisiana State University and the Louisiana Universities Marine Consortium is based on May nitrate loads on the Mississippi River at Baton Rouge.

Excess nutrients can spur the growth of algae, and when the algae die, their decay consumes oxygen faster than it can be brought down from the surface. As a result, fish, shrimp and crabs can suffocate, threatening the region's commercial fishing industry.

R. Eugene Turner, who led the recent modeling effort, said in a statement that intensive farming — including working land for crops used to make biofuels — has contributed to the high rate of nitrogen loading.

Researchers say the largest dead zone measured was 8,894 square miles in 2002. It was about 7,900 square miles last year.

Many scientists believe the nation's corn crop is partly responsible for the dead-zone, which is caused, in part, by nitrogen that enters the Mississippi River as runoff. Nitrogen is a key ingredient in corn and soybean fertilizer.