[Simulation and evaluation on TIN and PO4(3-) -P reduction in Deep Bay, China]

Environmental Fluid Dynamics Code (EFDC), three-dimensional hydrodynamic and water quality models, are employed to simulate the transport of total inorganic nitrogen (TIN) and orthophosphate (PO4(3-) -P) in Deep Bay, China under different hydrologic conditions. It shows that, the computational results of TIN and PO4(3-) -P match very well with monthly-averaged field data in dry and wet seasons. The results of TIN and PO4(3-) -P reduction scenarios show that, it is necessary to reduce TIN concentration in Pearl River to Grade III to guarantee TIN in Deep Bay comply with the marine functional zonation requirement of the standard of Grade III. TIN and PO4(3-) -P concentrations in Deep Bay could comply with the marine functional zonation requirement if 95% TIN and PO4(3-) -P loading are reduced from the inflow when degradation ignores. When the degradation is considered, TIN could comply with the marine functional zonation requirement if 83% TIN loading are reduced from the inflow.