How Will Biofuels Production Affect “Dead Zones” in Gulf of Mexico and Elsewhere?

Nutrient run-off from agriculture contributes significantly to the formation of extensive, oxygen-depleted, “dead zones" in the Gulf of Mexico, the Chesapeake Bay, and in water bodies elsewhere across the country. Efforts have been underway for some time to restore aquatic ecosystems, but relatively little progress has been made to date. How can these efforts be improved, and how will the increasing production of biofuels from corn, soy, and cellulosic feedstocks, as mandated by the Renewable Fuel Standard, affect these restoration efforts? Questions such as these have inspired a recent congressional hearing, new legislation, and recent research.

On September 17, the House Committee on Science and Technology Subcommittee on Energy and Environment held a hearing to discuss draft legislation The Harmful Algal Blooms and Hypoxia Research and Control Amendments Act of 2009 . In his opening statement , Subcommittee Chairman Brian Baird (D-WA) observed, “Harmful algal blooms pose serious threats because of their production of toxins and reduction of oxygen in the water. These impacts include alteration of the ocean’s food web, human illnesses, and economic losses to communities and commercial fisheries.” The bill would “develop and coordinate a comprehensive and integrated strategy to address harmful algal blooms and hypoxia, and to provide for the development and implementation of comprehensive regional action plans to reduce harmful algal blooms and hypoxia.” Rep. Baird and ten cosponsors subsequently introduced H.R. 3650 on Sept. 25. Similar legislation (S. 952) has been introduced in the Senate by Senator Olympia Snowe (R-ME).

According to the Centers for Disease Control and Prevention , scientists still do not know the full affect of harmful algal blooms on human health, but it is known that cyanobacteria, harmful marine algae associated with red tide, and Pfiesteria piscicida can cause rashes, gastrointestinal illnesses, confusion, allergic reactions, and death in some cases.

One of the major known causes of harmful algal blooms and hypoxia is nutrient runoff from agricultural production. A recent study , “Impact of Biofuel Crop Production on the Formation of Hypoxia in the Gulf of Mexico,” published in the Environmental Science and Technology Journal , examines the potential impact of nitrate pollution under different biofuel production scenarios through 2022, consistent with meeting the biofuel production levels mandated in the Renewable Fuel Standard.

At present, nutrient run-off from agriculture (primarily from corn and soy production) is responsible for about half of the excess nutrient load in the northern Gulf of Mexico. The study found that by shifting from corn-based ethanol production to using increasing amounts of cellulosic feedstocks (e.g. corn stover and switchgrass), nitrate output from the Mississippi watershed, which feeds into the northern Gulf of Mexico, could be reduced by as much as 20 percent by 2022, if best management practices are consistently applied. However, this would fall far short of what would be needed to reduce the size of the hypoxia zone from the current five-year annual average of 14,600 km2 down to EPA’s goal of 5,000 km2. A much more aggressive nutrient management approach will be needed in order to reach this goal. The authors conclude: “[O]nly when all of the nitrogen runoff associated with the production of corn, soy, and switchgrass is reduced will the EPA goal be met.”