A practical application of Droop nutrient kinetics (WR 1883)

Algal growth kinetics based on internal phosphorus concentration were incorporated into an existing eutrophication model. Application to a closed system resulted in damped oscillations in algal biomass and phosphate relative to a model with fixed composition. Peak biomass did not differ substantially, however, from that attained using a model with fixed, minimal phosphorus-to-carbon ratio. Sensitivity analyses were conducted following model application to the lower St. Johns River, Florida. Factor-of-two changes in key parameters had little influence on computed chlorophyll. Varying model parameters exerted a larger influence on dissolved phosphate concentration. We conclude Droop kinetics present a mechanism for regulating computed nutrient concentrations rather than computed chlorophyll concentrations.