Modeling transient storage and nitrate uptake kinetics in a flume containing a natural periphyton community

An existing transport model including storage zones was combined with a submodel describing biotic retention of nutrient based on Michaelis‐Menten kinetics. This transport/retention model was used to simulate the results of an experiment in which the inflows to flumes containing nitrate‐limited natural stream periphyton on artificial substrates were amended with chloride and nitrate. Hydrodynamic parameters were determined by fitting the model to the chloride data. The Michaelis‐Menten maximum uptake rate parameter was determined by fitting the model to the nitrate data. The transport/retention model accurately simulated the responses of the flumes to the amendments. Independent batch experiments to determine Michaelis‐Menten parameters were performed on periphyton from a control flume. The maximum uptake rate parameters from the two experiments are in good agreement. Both experiments indicate possible inadequacies of the Michaelis‐Menten kinetic model for describing nutrient uptake in a complex field community.