View of the Mississippi River from Perot State Park

International Conference on Rivers and Civilization:
Multidisciplinary Perspectives on Major River Basins


La Crosse, Wisconsin USA
June 25-28, 2006

HOST AND PRESENTER INSTITUTIONS
University of Wisconsin-La Crosse Home Page National Mississippi River Museum and Aquarium Home Page

CONFERENCE SPEAKER

Robert Howarth(Cornell University, USA): Human Alteration of the Nitrogen Cycle in Large Watersheds: Causes, Consequences, and Steps Towards Solution. (Abstract)

photo of Robert Howarth Robert W. Howarth earned degrees from Amherst College (BA, 1974) and jointly from MIT and the Woods Hole Oceanographic Institution (PhD, 1979).  He was a scientist at the Marine Biological Laboratory (Woods Hole) from 1980 to 1985 and has held an adjunct appointment there since 2000.  Since 1985, Howarth has been on the faculty at Cornell University (the David R. Atkinson Professor of Ecology & Environmental Biology since 1992).  He was founding Editor and Editor-in-Chief of the journal Biogeochemistry from 1983 to 2003, was Co-Chair of the International SCOPE Nitrogen Project from 1993 to 2002, chaired the US National Academy of Sciences Committee on Causes and Consequences of Coastal Eutrophication from 1998 to 2000, and has been Director of the North American Nitrogen Center since 2003.
http://www.eeb.cornell.edu/howarth/default.html

Abstract: Nutrients are the largest pollution problem in the coastal waters of the United States, and increased inputs over the past several decades have resulted in the degradation of 2/3rds of the nation's coastal rivers and bays. Effects include hypoxia and anoxia, increased incidences of harmful algal blooms, degradation and alteration of habitat and food-web structure, and loss of biotic diversity. Although phosphorus can contribute to this degradation, the major culprit is nitrogen in most coastal marine ecosystems (in sharp contrast to freshwater lakes, where phosphorus pollution is of greater concern). Nitrogen is far more mobile in the environment than is phosphorus, and management practices that often were designed to control phosphorus pollution sometimes fail to recognize the greater mobility of nitrogen. Human activity has roughly doubled the creation of reactive, biologically available nitrogen on the land masses of the Earth. Regional variation in this increase is great, and some large rivers have seen little change, while in other rivers, nitrogen fluxes have increased by 10- to 15-fold or more. Much of this increase has occurred over the past few decades. Increased use of synthetic nitrogen fertilizer and increased intensity of meat production have led the change globally and in many regions (including the Mississippi River basin), but atmospheric deposition of nitrogen from fossil-fuel combustion also contributes globally and is the largest single source of nitrogen pollution in some regions (such as much of the northeastern United States). Because of this regional variation in the sources of nitrogen pollution, management approaches need to be tailored to particular regions. Technical solutions for reducing nitrogen pollution from all sources exist, and generally at reasonable cost. However, effective implementation of solutions for non-point sources of nitrogen pollution has been spotty at best in most watersheds.