Aplicação do modelo EPA-Aquatox à Baía de Vitória (ES)

Abstract

Estuaries are environments in which human activities have caused several changes and negative impacts. One example is the release of untreated sewage, which in Vitoria Bay generates a very significant input of nutrients and organic matter, resulting in disturbances in the ecosystem. Computational models have been used as a tool for environmental management of water quality related with organic input, but models that use biological concepts, called ecological models, to evaluate consequences in estuarine chemical-physical and biology have not been used. The present study aimed to use an ecological model, the EPA-Aquatox, to assess its effectiveness, through simulations, for reproduction of water quality in Vitoria Bay, and analysis of consequences of organic pollution in the estuarine environment. It was conducted a literature search of ecological data relating physics, chemistry, and biology to implement the model. Sensitivity analysis showed that, the most sensitive state variables were obtained by using detailed studies and historical series of measurements, as expected, according to literature, for the parameters phosphorus, BOD, ammonia and chlorophyll. The calibration of the model showed that the best adjustment is to use 55% of the total estimated for the contribution of urban organic load. Through simulations of scenarios for the years 2009 and 2010, it was observed that the contribution of urban organic is much more significant to the Vitoria Bay than river organic loading contribution. After the conclusion of “Águas Limpas” civil works, there will be a significant improvement in water quality, however, at times it´s quality will not be in good condition, considerating parameters like phosphorus and ammonia according to the CONAMA resolution 357.