Nitrogen-Cycle Model for Aquatic Systems: Analysis

Formulation and analysis of a nitrogen-cycle model for aquatic systems is described. The transformations of elemental nitrogen from the nutrient species to different phytoplankton and zooplankton species biomass are presented. The dynamic behavior of the cycle, at different levels of complexity, is investigated using realistic initial conditions and transformation governing kinetic rates. To assess the effects of different environmental forcing functions on the behavior of the nitrogen cycle, model results are analyzed under simplified flow and no-flow conditions. A methodology to study sensitivity of the cycle behavior under transient conditions is advanced. The results of the study indicate that added structural complexities to model reveal discernible changes in model response to identical input conditions, the state-of-the-art is lacking to simulate short-term species succession in ecosystems, and sensitivity analyses of nonlinear systems under transient condition is possible.