Water Resources Research Act Program

Details for Project ID 2010AZ407B

Sources and transport of nitrogen from sky-island ecosystems to groundwater basins

Institute: Arizona
Year Established: 2010 Start Date: 2010-03-01 End Date: 2011-02-28
Total Federal Funds: $10,000 Total Non-Federal Funds: $20,000

Principal Investigators: Jennifer McIntosh, Kathleen Lohse, Armin Sorooshian

Abstract: Atmospheric deposition of nitrogen (N) is a significant source of nutrients and contaminants to the land surface that can impact water quality, biodiversity, and ecosystem function. Some of the highest rates of N deposition (primarily from anthropogenic activities) in the Western United States have been reported in semi-arid high elevation catchments adjacent to urban areas. These mountain systems are important sources of recharge to adjacent alluvial groundwater basins. Despite this, relatively little is known about the importance and magnitude of N inputs to sky-island systems and the transport of this atmospheric N through mountain catchments to groundwater basins. We propose to investigate the dominant sources of N input to the Santa Catalina Mountains (what proportion is coming from atmospheric vs. terrestrial sources?), and evaluate the impact of climate and bedrock type (lithology) on N reaction and transport. To do this, we will measure the N-species composition (NO3, NO2, NH4, amines, organic-N) and stable isotopes (δ15N, δ18O, Δ17O) of atmospheric deposition, soil pore waters, and surface waters at multiple elevations in the Santa Catalina Mountains underlain by different bedrock types. Results from this study will provide an increased understanding of the sources and amounts of nitrogen being deposited to sky-island ecosystems, and how nitrate is retained and/or transported from mountain catchments to adjacent groundwater basins. We are seeking funding to cover the analytical costs and partial student support. The proposed study is made possible by significant cost-sharing from a current State of Arizona Water Sustainability Program grant.