HR: 11:30h
AN: NB22E-05    [Abstracts]
TI: Denitrification in an Urban Greenbelt: Contrasting Aquatic and Terrestrial Patches
AU: * Roach, W J
EM: john.roach@asu.edu
AF: School of Life Sciences, Arizona State University, P.O. Box 874501, Tempe, AZ 85287 United States
AU: * Roach, W J
EM: john.roach@asu.edu
AF: Urban Ecology IGERT, Center for Environmental Studies, Arizona State University, P.O. Box 873211 , Tempe, AZ 85287 United States
AU: Grimm, N B
AF: School of Life Sciences, Arizona State University, P.O. Box 874501, Tempe, AZ 85287 United States
AU: Grimm, N B
AF: Center for Environmental Studies, Arizona State University, P.O. Box 873211, Tempe, AZ 85287 United States
AB: The Indian Bend Wash flood-control project relies on a greenbelt to safely convey floods through Scottsdale, AZ. A chain of shallow artificially maintained lakes sitting in a larger, protected floodplain of irrigated turf grass characterizes the greenbelt. We conducted a series of experiments exploring how the creation of novel patch types affected denitrification in the wash. DEA analyses on sediments collected from eight lake and six stream segments as well as soil samples from eight floodplain transects demonstrated that mass-specific potential denitrification rates were significantly higher in lakes than in streams or floodplains. Nutrient limitation bioassays revealed that NO₃-N limited denitrification in lake sediments while floodplain soils were limited by the availability anaerobic conditions created by water additions. Although rain events are rare in the desert, irrigation is common and we conclude that annual denitrification in the floodplain can be substantial. Because lake water NO₃-N concentrations often exceed 1 mg/L, the finding that NO₃-N limited denitrification in the sediments was surprising. However, further experiments using intact cores demonstrated that it was not so much the availability of NO₃-N in the overlying water as the rate the nitrate diffused into the sediments that limited denitrification in the lakes.
DE: 9901 NABS Student Award - Basic Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly