Proposal: DEB 0507973 PI: Ehrenfeld, Joan Institution: Rutgers
Human activities, in particular fossil fuel combustion and fertilizer production, are adding vast quantities of nitrogen (N) to ecosystems. This excess N causes numerous environmental problems, including eutrophication, hypoxic coastal waters, loss of species diversity, and drinking water toxicity. Wetland systems typically have a high capacity to retain N because their wet soils promote denitrification, a soil process which converts nitrate to nitrogen gases. Wetlands in urban areas, however, may not have the same ability to remove N because hydrological alterations resulting from urbanization make urban wetlands drier than they have been historically, thus inhibiting the N-removing process of denitrification. Although it is known that both intrinsic soil mineralization and N from atmospheric deposition are important sources of nitrate in these disturbed wetlands, it is not known which source of N contributes to the release of N to surface waters. We will use a novel method, based on a dual isotope approach using 15N and 18O, which has not yet been tested in urban wetland ecosystems, to distinguish between N from precipitation and N from soil in soil water samples collected deep in the soil profile. Distinguishing soil and atmospheric sources of N leached to surface waters will have important implications for environmental management and policy. This research will also be a contribution to the emerging field of urban ecology. The research will be communicated in articles for the general public in the publications of such organizations as the NJ Audubon Society, the NJ Conservation Foundation, the NY/NJ Trail Conference, the NJ Water Resources Research Institute, and the Raritan Baykeeper, organizations that are all heavily involved in the management and conservation of wetlands in urbanizing regions.
