Spring Nitrate Flux in the Mississippi River Basin: A Landscape Model with Conservation Applications

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• 作者：Mary S. Booth ; Chris Campbell
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：August 1, 2007
• 年：2007
• 卷：41
• 期：15
• 页码：5410 - 5418
• 全文大小：483K
• 年卷期：v.41,no.15(August 1, 2007)
• ISSN：1520-5851

文摘

Nitrogen derived from fertilizer runoff in the MississippiRiver Basin (MRB) is acknowledged as a primary cause ofhypoxia in the Gulf of Mexico. To identify the locationand magnitude of nitrate runoff hotspots, and thus determinewhere increased conservation efforts may best improvewater quality, we modeled the relationship between nitrogeninputs and spring nitrate loading in watersheds of theMRB. Fertilizer runoff was found to account for 59% ofloading, atmospheric nitrate deposition for 17%, animalwaste for 13%, and municipal waste for 11%. A nonlinearrelationship between nitrate flux and fertilizer N inputsleads the model to identify a small but intensively croppedportion of the MRB as responsible for most agriculturalnitrate runoff. Watersheds of the MRB with the highest ratesof fertilizer runoff had the lowest amount of land enrolledin federal conservation programs. Our analysis suggeststhat scaling conservation effort in proportion to fertilizer useintensity could reduce agricultural nitrogen inputs to theGulf of Mexico, and that the cost of doing so would be wellwithin historic levels of federal funding for agriculture.