HR: 1330h
AN: H13A-02    [Abstracts]
TI: Watershed Characteristics Influencing Stream Nutrient Concentrations Across a Rural-to-Urban Land Use Gradient
AU: * Pellerin, B A
EM: bpeller@usgs.gov
AF: USGS, 6000 J Street, Placer Hall, Sacramento, CA 95831 United States
AU: Wollheim, W M
EM: wollheim@eos.sr.unh.edu
AF: Water Systems Analysis Group, Institute for the Study of Earth, Oceans, and Space University of New Hampshire, Durham, NH 03824 United States
AU: Vorosmarty, C J
EM: charles.vorosmarty@unh.edu
AF: Water Systems Analysis Group, Institute for the Study of Earth, Oceans, and Space University of New Hampshire, Durham, NH 03824 United States
AU: McDowell, W H
EM: bill.mcdowell@unh.edu
AF: Department of Natural Resources, James Hall Unversity of New Hampshire, Durham, NH 95831 United States
AU: Hopkinson, C S
EM: chopkins@unh.edu
AF: The Ecosystems Center, The Marine Biological Lab, Woods Hole, MA 02543 United States
AB: We assessed the influence of several watershed-scale features on mean annual stream inorganic nitrogen (N) and phosphorus (P) concentrations in 23 urbanizing catchments (rural-to-urban) dominated by non-point source inputs. Population density was not a strong predictor of N or P concentrations across the gradient, while residential land use (%) explained 52% of the NO₃ variability both across the gradient and even more variability (0.70%) in a subset of catchments with intermediate population densities (suburban, 100 to 620 people / km²). A multiple regression using percent wetlands and septic density explained a similar amount (51 and 73 %) of the NO₃ variability across the rural-to-urban gradient and within suburban watersheds, highlighting the potential role of septic wastewater and wetlands as N sources and sinks, respectively. Isotopic data (¹⁵N-NO₃) suggested that wastewater was the dominant source of NO₃ in suburban and urban watersheds. While residential land use was the best single predictor, it provided little information on mechanisms controlling stream chemistry. In contrast, the use of wetland percentage and septic density in a multiple regression explained as much variability and suggested key sources and sinks for management at the watershed-scale.
DE: 1803 Anthropogenic effects
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
DE: 1890 Wetlands
SC: Hydrology [H]
MN: 2005 Joint Assembly