Tue Jul 29, 2008 3:54PM
The official measurements are in, and the Gulf of Mexico "Dead Zone" is the second-largest ever recorded.
Hurricane Dolly, which churned through the Gulf last week, may have mixed in enough oxygen to thwart researchers' predictions that this year's Dead Zone would exceed the largest on record, in 2002. Had the survey been conducted earlier, before Dolly, the official estimate would have gone in the books as significantly larger.
But there's small consolation in a lifeless zone of water off the American coast that covers 7,988 square miles, slightly bigger than in 2007, and about the size of Massachusetts. It failed to reach the New Jersey-sized proportions predicted.
The Gulf Dead Zone was so large this year for several reasons.
One prime culprit: The record Midwest flooding that caused the Mississippi to swell. The discharge of pollutants and nutrients from the Mississippi River causes algae to bloom in the Gulf of Mexico. When the algae dies, the decaying absorbs so much oxygen from the water that large areas become inhospitable to fish. The resulting lifeless area is called a eutrophic or hypoxic zone, or more colloquially, a dead zone. The condition is cyclic, and reaches its maximum in late summer.
Researchers emphasized the exceptional flow of water from the Mississippi as a prime driver of their prediction, but the other major reason is the use of fertilizers on farms across the Midwest. In 50 years, since the advent of modern agricultural techniques and changes to federal farm policy, farmers have increasingly planted more corn per acre, which depletes the soil and requires heavier inputs of chemical fertilizer. Most nitrogen fertilizers are derived from natural gas, so they are essentially a fossil fuel for food.
The acreage of corn planted, and the use of fertilizer, has skyrocketed in the past couple of years as Congress set quotas on the use of ethanol, an alternative fuel that in the United States is made primarily from corn. As requirements to use more ethanol increased, so did corn acreage and fertilizer used.
This could very well be another reason for the nation to focus more attention on growing organically. Organic farming does not use the nitrogen fertilizers that are responsible.
The World Resources Institute recently mapped the world's dead zones and found a whopping 415 eutrophic (nutrient-saturated) zones, including 169 that are known to be hypoxic (devoid of oxygen) and another 169 that probably are. The researchers believe the number is much higher, since only the United States and the European Union do an adequate job of counting and reporting problem coastal areas. China and other fast-growing Asian economies are likely polluting their coasts, but the problem hasn't been documented, the researchers say.