Scientists predict large ‘dead zone’

Washington, D.C.-A team of scientists from The National Oceanic and Atmospheric Administration (NOAA), the Louisiana Universities Marine Consortium, and Louisiana State University is forecasting that the “dead zone” off the coast of Louisiana and Texas this summer – an area of low or no oxygen that can threaten marine life – has the potential to be the largest since shelf-wide measurements began in 1985, and significantly larger than the average size since 1990. The NOAA-supported modeling effort, released on July 17, predicts this summer’s “dead zone” in the Gulf of Mexico may be as large as 8,500 square miles, an area about the size of New Jersey. The forecast is based on nitrate loads from the Mississippi and Atchafalaya rivers in May, and incorporates the previous year’s conditions. Since 1990, the average annual hypoxia-affected area has been approximately 4,800 square miles, but measured 6,662 square miles in 2006, NOAA said. One of the study’s researchers said the riverine flow in May 2007 contained 35 percent more nitrogen than in May 2002, which he said “may be due to more intensive farming of more land, including crops used for biofuels, unique weather patterns, or changing farming practices.” The researchers say the LSU model is the most accurate based on past performance, but is still in the experimental stages, and additional research is required before it becomes an operational forecast. The fertilizer industry has long questioned how much of a role fertilizer use plays in the Gulf hypoxia zone. Earlier this month, The Fertilizer Institute submitted 14 pages of comments to EPA on its Draft Science Advisory Board (SAB) Hypoxia Report, in which TFI claimed that the poor correlation between nitrogen and/or phosphate fertilizer use and the size of the Gulf hypoxic zone indicates “a more complex problem than simply nutrient over-enrichment,” and that the report should take into account all sources of nutrients and their ability to be controlled (GM July 9, p. 10). TFI also argued that fertilizer use efficiency is at an all-time high, and estimated that U.S. farmers since 1980 are applying 41 percent less nitrogen and 53 percent less phosphate per bushel of corn produced. TFI said progress has also been made in conservation practices such as wetland and riparian buffer creation and restoration.