HR: 14:25h
AN: B33G-04 INVITED     [Abstracts]
TI: It's all about connections: coupled hydrological and biogeochemical cycles affecting delivery of nitrogen to surface waters
AU: * Boyer, E W
EM: boyer@nature.berkeley.edu
AF: University of California, Dept. of Environmental Science, Policy and Management, Berkeley, CA 94720 United States
AU: Alexander, R B
EM: ralex@usgs.gov
AF: US Geological Survey, 12201 Sunrise Valley Drive, Reston, VA 20192 United States
AU: Sebestyen, S D
EM: sds@nature.berkeley.edu
AF: University of California, Dept. of Environmental Science, Policy and Management, Berkeley, CA 94720 United States
AU: Shanley, J B
EM: jshanley@usgs.gov
AF: US Geological Survey, Water Resources Discipline, Montpelier, VT 05602
AU: Smith, R A
EM: rsmith1@usgs.gov
AF: US Geological Survey, 12201 Sunrise Valley Drive, Reston, VA 20192 United States
AB: Cycles of nitrogen, carbon, and water are tightly linked in both terrestrial and aquatic ecosystems. In this presentation, we explore how flowpaths and residence times of water in landscapes shape delivery of water and nitrogen (N) from landscapes to surface waters. First, we present long-term monitoring data from watershed studies in Vermont, Colorado, and New York. There we are monitoring N dynamics under varying hydrological regimes such as events and seasons, and have characterized flow paths and N sources. Second, we present results from a spatially referenced regression model quantifying N sources and fluxes in riverine systems at regional scales with an empirical modeling approach. The simulations provide information about the role of delivery of atmospheric N from the terrestrial landscape to surface waters, and the role of in-stream processing in altering N loads during transport to downstream receiving waters. Both of these approaches illustrate the coupled role of water and nitrogen cycles in controlling the temporal variation of. N in surface waters, and suggest factors controlling "hot spots" and "hot moments" from which high N loads arise. Our work sheds light on how processes occurring throughout the mosaic of land uses comprising upland watersheds combine to determine N loads in the downstream receiving waters.
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 1804 Catchment
DE: 1806 Chemistry of fresh water
SC: Biogeosciences [B]
MN: Fall Meeting 2005