Impact of Mountain Resort Development on Stream Water Nitrogen Export: The Importance of Spatial LocationEPA Grant Number: F6E10272
Title: Impact of Mountain Resort Development on Stream Water Nitrogen Export: The Importance of Spatial Location
Investigators: Gardner, Kristin
Institution: Montana State University
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2006 through August 31, 2009
Project Amount: $97,478
RFA: STAR Graduate Fellowships (2006) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Aquatic Ecosystems , Fellowship - Aquatic Systems Ecology
Land use/land cover (LULC) change has been shown to be a significant threat to aquatic ecosystems, and yet the understanding of the linkages between land use and water quality is inadequate to inform land management decisions. Nitrogen is a contaminant of particular concern because of its high mobility in soils and its association with development (wastewater, fertilizer). Nitrogen (N) is the most common limiting nutrient in North American forested ecosystems. With increasing residential development and escalating inputs of N to localized geographic areas of a watershed, those areas may reach a condition known as “N saturation”. When N saturation is reached additional N inputs are in excess of biological requirements and are “leaked” to streams and groundwater. At the watershed scale, I propose that not only the amount and type of landscape alteration, but also the spatial location will dictate the spatial and temporal patterns of stream water nitrogen.
This research develops an innovative method to examine the impact of geographic location and spatial distribution of LULC change on the spatial, seasonal, and temporal patterns of stream water nitrogen (N). The spatial locations of LULC (e.g. vegetation, on-site septic systems, pavement, riparian features, residential development, water, and recreational facilities) and watershed characteristics (e.g. soils, geology, topography, topology, and hydrological flow paths) will be determined from high-resolution remote-sensing imagery data (QuickBird) and airborne laser mapping (ALSM) topography data. Stream water will be sampled in both synoptic events at 55 sites - four times a year and weekly, at 9 sites. Stream water samples will be analyzed for all species of nitrogen, phosphate, anions, cations, and the δ15N and δ18O of nitrate. The relationships between LULC, watershed characteristics, and water quality will be determined by developing a physically based, spatially explicit nitrogen export coefficient model that incorporates not only LULC class percentages, but the spatial pattern (organization and location) of this LULC to quantify and model the impacts of LULC on stream ecosystem function and water quality. The export coefficient model will be validated by performing isotopic analysis using the stable isotopic rations of δ15N and 18O of NO3- to estimate the relative contributions of stream water nitrate sources.
The relationships quantified in the export coefficient model will identify spatial and geographic characteristics that lead to localized nitrogen saturation and increased nitrogen export to stream water. The results will provide land managers with tools to identify areas vulnerable to nitrogen saturation and increased export to stream water.