You are here:
Quantifying seasonal shifts in nitrogen sources to Oregon estuaries using a transport model combined with stable isotopes
Citation:
BROWN, C. A. AND J. E. KALDY, III. Quantifying seasonal shifts in nitrogen sources to Oregon estuaries using a transport model combined with stable isotopes. Presented at Pacific Estuarine Research Society Meeting, Newport, OR, February 28 - March 01, 2008.
Impact/Purpose:
Identifying the sources of dissolved inorganic nitrogen (DIN) in estuaries is complicated by the multiple sources, temporal variability in inputs, and variations in transport.
Description:
Identifying the sources of dissolved inorganic nitrogen (DIN) in estuaries is complicated by the multiple sources, temporal variability in inputs, and variations in transport. We used a hydrodynamic model to simulate the transport and uptake of three sources of DIN (oceanic, riverine and wastewater treatment facility effluent) to Yaquina Bay, Oregon, USA. Model results were used to determine the importance of advective transport and mixing of DIN sources on spatial and temporal patterns in stable isotope (delta 15N) of macroalgae. Model simulations combined with stable isotope data reveal that riverine sources dominate during the wet season, coastal upwelling is the major source of nitrogen during the dry season, and wastewater effluent is a minor source. Our novel use of a transport model coupled with stable isotopes allowed the quantification of sources of DIN within the estuary, which would not have been possible using the traditional approach of mixing diagrams, due to the number of sources and the temporal variability in inputs.