Eulerian modeling of radionuclides in surficial waters: the case of Ilha Grande Bay (RJ, Brazil) The passive scalar approach allows the decoupling of the transport modeling from the hydrodynamic circulation modeling. In this respect, the implicit hypothesis is that the hydrodynamic circulation in the far field is independent of the concentration distribution of a given constituent. The decoupling of the transport model from the hydrodynamic model allows the negligence of baroclinic forcing in the latter. In order to model the transport of constituents for a given scenario, the pertinent hydrodynamic circulation will be previously modeled. Some scenarios of hydrodynamic circulation and transport of contaminants are simulated with the SisBAHIA platform.