A stoichiometric model for water quality interactions in macrophyte dominated water bodies

A computer model, SIREM1, which incorporates water quality interactions of aquatic plants including planktonic algae, periphyton, and macrophytes is presented in this paper. In this model, the total amount of aquatic plants is represented dynamically as an oxygen equivalent, dependent upon available solar radiation. Through the stoichiometric relationship between plant protoplasm and processes including photosynthesis, respiration, and death, nutrients and autochthonous organic matter are computed based on simulated oxygen equivalents. The model was applied to an impounded stream where macrophytes played an important role in water quality dynamics. There was good comparison between model prediction and actual observations. The results indicate that the time variable oxygen equivalent concept for aquatic plants could be a useful approach for simulating the function of aquatic plants in diurnal dissolved oxygen variations, nutrient uptake/recycle, and the generation of autochthonous organic matter.