LTER Cross-site: Dissolved Organic Nitrogen Intersite Comparison (DONIC)

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Williams, Mark W. and Diane McKnight University of Colorado -Boulder DEB 0087248 " Dissolved organic nitrogen intersite comparison (DONIC)" Dissolved organic nitrogen (DON) is a major component of nitrogen inputs and outputs in watersheds, yet it has not been quantified adequately in most ecosystems. This proposal offers a synthesis of what is currently known about DON, and how it may be a key indicator of ecosystem processes and responses to increased inorganic N deposition. The PIs plan to conduct work at many LTERs sites from across the globe ( Luquillo, Hubbard Brook, Bonanza Creek, Toolik Lake, McMurdo Dry Valleys, Santa Barbara Coastal, Sierra Nevada, Niwot Rigdge). The PIs also plan to bring the PIs from multiple LTER sites together for discussions of methods. The specific objectives are to determine if DON inputs and outputs are a measurable and important component of the N-cycle from cold regions to warm regions and over a wide range of inorganic inputs; evaluate whether DON output makes up a substantial fraction of dissolved N lost from ecosystems with low N availability; test whether DON export is controlled by microbial activity; explore whether the N status of an ecosystemn can be evaluated by the ratio of DOC:DON and NO3-N: DON in annual export from streams; determine the bioavailability of DON using two isolation techniques; and discriminate terrestrial and aquatic sources of DON using florescence excitation matrices of humic material.