Real Time Simulation of Nitrogen Cycle in an Estuary

Abstract

A water quality model containing seven nitrogen storage variables appropriate to an aerobic, nitrogen limited, aquatic ecosystem is described. The model distinquishes between various organic and inorganic forms of nitrogen including phytoplankton and zooplankton, but assumes that net settling and resuspension of particulate organic nitrogen is negligible. The model is applied to a chemostat system to demonstrate damped cyclic behavior. A case study of an idealized estuary is used to demonstrate the coupling between hydrodynamic transport, mixing, and biochemical transformations. It is shown that nutrient concentrations are highly sensitive to the representation of the real time (intratidal cycle) transport. Application of the nitrogen cycle model to the Potomac estuary illustrates the large temporal variation of the nitrogeneous constituents. Implications on future research directions and field data collection techniques are presented.