Senior Project Advisor
Hood Canal, Denitrification, Estuary, Circulation, Estuarine Circulation, Nitrogen, Nitrogen Cycle, Dissolved Oxygen, Hypoxia, Salish Sea
Hood Canal is a long, fjordal estuarine inlet. Because of a sill near its mouth, Hood Canal experiences regular low oxygen in its bottom water; recently, dissolved oxygen has been even lower than usual, leading to fish kills and other ecosystem damage. Anthropogenic nutrients, particularly nitrogen, may be the cause, so it is important to quantify the components of the nitrogen cycle, like denitrification. To my knowledge, there is only one estimate of denitrification from Hood Canal in the literature. This study sought to supplement that data with an independent estimate of denitrification using water circulation along with N2 concentrations from the bottom of the water column at 4 stations in Hood Canal. I used Matlab to calculate mean flow velocities from instantaneous velocities generated by the Salish Sea Model. I started by using a simple 2-layer flow model with perfect diffusion through the bottom layer, but a high estimate led me to transition to an advection-diffusion partial differential equation model. This model yielded inconclusive results; the high denitrification outputs suggested that maybe the diffusion constant found in the literature increased too much with depth. Future studies could measure N2 concentrations at different depths to better fit the diffusion constant or change the mean flow velocity in the model to vary with time.
Johnson, Spencer, "Estimating the Denitrification Rate in Hood Canal using Water Circulation" (2021). WWU Honors College Senior Projects. 463.
Subjects - Topical (LCSH)
Denitrification--Washington (State)--Hood Canal--Measurement; Water currents--Washington (State)--Hood Canal--Measurement; Estuaries--Hydrodynamics; Hypoxia (Water)--Washington (State)--Hood Canal
Hood Canal (Wash.)
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