Aquatic Sciences Meeting, Albuquerque 2001
|SS31 Integrated Approaches to Drainage Basin Nutrient Inputs and Inland/Coastal Eutrophication (Science and Society Connections)|
|Date: Thursday, February 15, 2001, Time: 9:45:00 AM|
|Howarth, R, W, Oceans Program, Environmental Defense, Boston, MA and Ecosystems Center, MBL, Woods Hole, MA, USA, email@example.com|
|HUMAN INFLUENCES ON THE DELIVERY OF NITROGEN TO COASTAL SYSTEMS: AN OVERVIEW|
|Nutrients are now the largest pollution problem in coastal marine ecosystems globally. In the US, some 60 percent of estuaries are moderately to severely degraded, primarily from N. Globally, human activity has roughly doubled the flux of N from land to the oceans, with much of this occurring over the past 40 years. The increase is much greater in some regions: some 4-fold in the Mississippi basin, 8-fold in the rivers of the northeastern US, and more than 10-fold in the rivers draining to the North Sea.|
Sources of N vary among estuaries. Sewage treatment plants are the largest input in some cases, but generally non-point sources are greater. Agriculture is the major source of N in many systems, including the flux down the Mississippi. Wastes from animal feedlots are a particularly large source in some locations, such as coastal North Carolina, and on average in the US probably exceed fertilizer runoff as a source of N to coastal waters. In some regions, including the northeastern US, atmospheric deposition of N from fossil fuel combustion is the major non-point flux.
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