HR: 09:30h
AN: NB31D-05 INVITED     [Abstracts]
TI: Apportioning Sources of Riverine Nitrogen at Multiple Watershed Scales
AU: * Boyer, E W
EM: boyer@nature.berkeley.edu
AF: University of California, Department of Environmental Science, Policy, and Management 137 Mulford Hall # 3114 , Berkeley, CA 94720-3114 United States
AU: Alexander, R B
EM: ralex@usgs.gov
AF: US Geological Survey, Water Resources Discipline 413 National Center 12201 Sunrise Valley Drive, Reston, VA 20192
AU: Sebestyen, S D
EM: sdsebest@syr.edu
AF: State University of New York, College of Environmental Science & Forestry 1 Forestry Drive, Syracuse, NY 13210 United States
AB: Loadings of reactive nitrogen (N) entering terrestrial landscapes have increased in recent decades due to anthropogenic activities associated with food and energy production. In the northeastern USA, this enhanced supply of N has been linked to many environmental concerns in both terrestrial and aquatic ecosystems, such as forest decline, lake and stream acidification, human respiratory problems, and coastal eutrophication. Thus N is a priority pollutant with regard to a whole host of air, land, and water quality issues, highlighting the need for methods to identify and quantify various N sources. Further, understanding precursor sources of N is critical to current and proposed public policies targeted at the reduction of N inputs to the terrestrial landscape and receiving waters. We present results from published and ongoing studies using multiple approaches to fingerprint sources of N in the northeastern USA, at watershed scales ranging from the headwaters to the coastal zone. The approaches include: 1) a mass balance model with a nitrogen-budgeting approach for analyses of large watersheds; 2) a spatially-referenced regression model with an empirical modeling approach for analyses of water quality at regional scales; and 3) a meta-analysis of monitoring data with a chemical tracer approach, utilizing concentrations of multiple elements and isotopic composition of N from water samples collected in the streams and rivers. We discuss the successes and limitations of these various approaches for apportioning contributions of N from multiple sources to receiving waters at regional scales.
DE: 1803 Anthropogenic effects
DE: 1806 Chemistry of fresh water
DE: 1871 Surface water quality
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly