Anthropogenic influences on a mediterranean Nature Reserve: modelling and forecasting

The lagoon of Biguglia (northeastern Corsica) is one of a number Nature Reserve. Anthropogenic activities are increasing over its watershed however. The present study aims to examine the state of health of the lagoon with the example of two pollutants (Cd and Cu). Water samples were collected in spring and summer 1997. The trace metal fluxes between the various compartments were measured. Transfer processes from the watershed to the lagoon were also examined. The temporal evolution of Cd and Cu content is assessed on the one hand by comparing the present data with former reference work (1992). On the other hand, a 5-box model is implemented in order to reduce the complex functioning of the lagoon to a system of differential equations. With the help of a numerical resolution method, the increase of metallic concentration levels is estimated since 1992. On the basis of 1997 data, two hypotheses are compared. The hypothesis that takes into account a growing increase of anthropogenic activities on the watershed gives, by extrapolation, results that are closer to field measurements. However, even with this hypothesis, the cadmium content in the lagoon is underestimated. This may signify that for this metal the evolution of the lagoon pollution is more important than a linear increase.