Part VIII – Conclusion
When important scientific claims are made there is typically a flurry of research and experiments, and a welter of different conclusions and interpretations. As data from different sources accumulates, however, it becomes clearer which interpretations are consistently supported, and which are not. Although a small minority of scientists continue to argue that the source of the nitrogen increase has not been proven, most scientists examining the data from numerous studies have concluded that fertilizer application in farms of the Mississippi River basin are the source of nitrogen that leads to the Dead Zone. The problem has moved slowly from scientific debate, to scientific consensus and into the arena of public policy and government action. The United States Geologic Survey released a report in January, 2008. Here is an excerpt from the accompanying news release which states unequivocally:
“Nine states in the Mississippi River Basin contribute the majority of nutrients to the Northern Gulf of Mexico, threatening the economic and ecological health of one of the nation's largest and most productive fisheries.
“Excessive nutrients have resulted in a zone of low dissolved oxygen or hypoxia, caused by the growth of large amounts of algae. This can stress and cause death in bottom-dwelling organisms in the Gulf.” (Alexander, et al., 2008)
Now that the cause of the Dead Zone has been determined, state and federal agencies are looking for ways to reduce nutrient pollution from farmlands before it enters the Mississippi River system. Voluntary reduction in fertilizer application, restoring wetlands along waterways, and establishment of vegetated buffering zones to absorb nutrients before they enter rivers and streams are among the action strategies being pursued. The goal is to reduce the area of the Dead Zone to 5,000 square kilometers by 2015. This represents about 1/3 the average square area of the Dead zone between 2003–2007. Achieving this goal will require overcoming many challenges, including reluctance of farmers to alter farming practices. In the mean time, small fishing operations near the Dead Zone will continue their struggle to survive.
Figure References
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Alexander, R.B., R.A. Smith, G.E. Schwarz, E.W. Boyer, J.V. Nolan, and J.W. Brakebill. 2008. Differences in phosphorus and nitrogen delivery to the Gulf of Mexico from the Mississippi River basin. U.S. Geological Survey. http://water.usgs.gov/nawqa/sparrow/gulf_findings/ Accessed: May 14, 2008.
Originally published at http://www.sciencecases.org/dead_zone/case8.asp
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