HR: 0800h
AN: B41D-0234    [Abstracts]
TI: Rainfall in Semiarid Ecosystems: Coupled Hydrology and Biogeochemistry Affect Nitrogen Cycling
AU: * Pullin, M J
EM: mpullin@nmt.edu
AF: Department of Chemistry, New Mexico Institute of Mining and Technology, Socorro, NM 87801 United States
AU: Vivoni, E R
EM: vivoni@nmt.edu
AF: Department of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology, Socorro, NM 87801 United States
AU: Harrison, B J
EM: bruce@nmt.edu
AF: Department of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology, Socorro, NM 87801 United States
AU: Andrews, J
EM: jross@nmt.edu
AF: Department of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology, Socorro, NM 87801 United States
AU: Vargas, A
EM: avargas_alexandra76@msn.com
AF: University of Texas El Paso, Department of Geological Sciences, El Paso, TX 79968 United States
AB: In semi-arid ecosystems, the timing, location, and amount of rainfall exert significant controls on the rates, duration, and location of biogeochemical cycling. This research seeks to examine the effect of rainfall magnitude and timing on redox processes occurring in desert soils and ephemeral stream channels. Simulated rain experiments indicate that soil wetting initiates nitrogen cycling that persists for days following an event. Observed nitrogen processes include transport of nitrate within the soil column, mineralization to ammonium, nitrification, and denitrification. Examination of a field site containing a series of interconnected stream channels indicates significant differences in the location of nitrate stored within the watershed. Additionally, high soil nitrate concentrations found at the terminus of the watershed created by a sediment dam indicate the net export of nitrate from the ecosystem. This suggests that nitrogen mineralization and nitrification rates are larger than plant uptake and/or denitrification rates or that nitrate production is hydraulically decoupled from plant uptake.
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 0471 Oxidation/reduction reactions (4851)
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: Fall Meeting 2005