摘要:A mathematical model is presented, consisting of a two-layer, finite difference hydrodynamic submodel and a compartmental water quality sub-model. The model is calibrated with field data. Then, it is applied to Southern Evoikos Gulf, an open coastal water body of particular ecological significance in the region of Attiki, in Greece. The application of the model aims at assessing the effect of three alternative treatment scenarios (i.e. biological treatment, biological treatment with N removal and biological treatment with N and P removal) performed in four sewage treatment plants (of a total capacity of 1,000,000 equivalent population) on the water quality of the Gulf. The calculations show that N is the limiting nutrient and its removal results in an improvement of the quality of the recipient, whereas the additional implementation of P removal has a rather limited impact.