The next figures represent a time series of the winter dissolved inorganic nitrogen (DIN) and phosphate concentrations measured in the Mondego estuary between 1993 and 1997 and also for 2005 and part of 2004. Each year is represented by the average of all field data in the winter season (January, February, March, September, October and December). The black line represents the moving average of two years. The moving average can allowing finding a trend for the field data and even with an obvious lacking of measurements it is possible to assume no significant variation on the winter DIN and Phosphate Concentration until 2005 and 2004 where there is a significant tendendy to decrease.
Figure 1	Figure 2
Figure 3 and 4 represent spatial distribution of the properties computed by MOHID Modelling System for the Mondego estuary. Figure 3 establishes the areas in which DIN concentrations are below the background value, between the background and the elevated level and the areas where the concentration is above the elevated. In Figure 4 is shown the salinity distribution in each area. The figures show clearly the existence of three different zones in the Mondego Estuary: seawater zone, mixing zone and tidal fresh zone. The limits of these areas for DIN and salinity distributions are identical. Generally, it is possible to say that, according to MOHID results, higher values of salinity correspond to areas of lower DIN concentrations and the range of DIN concentration between the back ground value and the elevated value correspond to the mixing area with salinity values that can range between 20 and 30. Thus, despite the average value considered to apply the assessment criteria, it is important to note that the model results evidence an important gradient of DIN concentrations in the estuary, characterize the actual situation with a large range of values, between 0 and 90 µmol N/L. Figure 5 represent the DIN vs. Salinity curve, based on field data registers. From the figure it is not viable to identify any clearly relation between the DIN and salinity values, but it is possible to observe a higher cloud of points corresponding to high values of salinity and lower DIN concentration. In fact, the irregular distribution can be related with the existence of a sluice controlling the Pranto river discharge. The characteristics of the south channel can change in a very significant way, if the sluice is closed, with salinity increases, as a consequence of hydrodynamic conditions changes. The figure shows all the existing samples, since it was not possible to distinguish the sluice state in the registers, which means that includes both conditions.	Figure 3
	Figure 4
	Figure 5

The North Channel has concentrations below the elevated level while in the South channel, the values can reach to 14 µ g/L. The model results show clearly the differences between the two channels indicated before.

Figure 4.

Oxygen Distribution

Figure 5 represents the annual average of oxygen spatial distribution in the estuary resulting form the model simulation. Oxygen concentration between 8 and 9 mg/L are found in most estuary and higher values are found in the south channel, in concordance with higher values of Chlorophyll-a.

Figure 5