Numerical Simulation of Phosphorus Release in an Urban Lake Based on a Diagenesis Model

Urban lakes are important components of urban ecosystems because of their water storage and regulation functions, and they represent landscape elements and recreational activity sites. The aims of this study are to develop a model of phosphorus diagenesis, which has been rarely assessed in lake water quality simulations, to simulate and analyse the dynamic release of phosphorus at the sediment–water interface and investigate the response relationship among the input load of phosphorus, the phosphorus flux from sediment, and the total phosphorus in lake water. The results indicate that the model is capable of continuously describing phosphate flux at the sediment–water interface. Under different testing scenarios, the sediment acts as a “buffer” that absorbs or releases phosphate to maintain a balance between the overlying water and sediment, thus providing phosphate for algae growth over a long time, even if large external loading is reduced. Therefore, using a diagenesis model to treat sediment release may be better than the traditional “assigned-value” method; therefore, this approach will probably be increasingly used in future modelling work.