ABSTRACT
RESUMO Foram avaliados os efeitos de ações antrópicas sobre o sistema costeiro de Ubatuba (SP) através de modelos que descrevem os mecanismos e as reações envolvidas na dispersão de indicadores microbiológicos (coliformes termotolerantes e enterococos) na água do mar. A análise da qualidade das águas destinadas à recreação, além de ser uma ação importante em termos de saúde pública, também se justifica em vista da importância da atividade turística em Ubatuba, possuindo, ainda, grande relevância para o planejamento ambiental. Na modelagem, foram utilizados os módulos do sistema Delft3D. No módulo de qualidade da água, foram estudados os mecanismos de dispersão dos poluentes, a partir da associação de dados de poluição com os resultados do módulo hidrodinâmico, em duas enseadas em Ubatuba (SP): Flamengo e Palmas. Os resultados obtidos permitem afirmar que o sistema de correntes nas enseadas, determinado pela geomorfologia da região, não confere alta capacidade de diluição e dispersão de efluentes na área de estudo. Todavia, a circulação marinha e os processos envolvidos no decaimento das bactérias são suficientes para difundir e diminuir suas concentrações ao longo das enseadas. Concluiu-se que a modelagem ambiental reproduziu de maneira satisfatória os processos envolvidos no transporte e na difusão de indicadores microbiológicos, contribuindo com os estudos sobre os efeitos das atividades antrópicas no sistema costeiro de Ubatuba.
ABSTRACT The effects of human activities on the coastal system of Ubatuba (SP) were evaluated through models that describe the mechanisms and reactions involved in the dispersal of microbiological indicators (thermotolerant coliforms and enterococci) in seawater. Analysis of the quality of water intended for recreation as well as being an important action in terms of public health, is also justified in view of the importance of tourism in Ubatuba, having also great importance to environmental planning. In modeling, the modules Delft3D system were used. In the water quality module, the pollutants dispersal mechanisms were studied, from the association of pollution data with the results of the hydrodynamic module, in two bays in Ubatuba: Flamengo and Palmas. The results allow us to state that the system of currents, determined by the geomorphology of the area, does not provide high capacity for dilution and dispersion of effluents in the study area. However, the marine circulation and the processes involved in the decay of bacteria are enough to spread and reduce their concentrations along the bays. It was concluded that environmental modeling reproduced satisfactorily the processes involved in the transport and diffusion of microbiological indicators, contributing to the studies on the effects of human activities on the coastal system of Ubatuba.
ABSTRACT
Recreational water quality is commonly assessed by microbial indicators such as fecal coliforms. Maceió is the capital of Alagoas state, located in tropical northeastern Brazil. Its beaches are considered as the most beautiful urban beaches in the country. Jatiúca Beach in Maceió was found to be unsuitable for bathing continuously during the year of 2011. The same level of contamination was not observed in surrounding beaches. The aim of this study was to initiate the search for the sources of these high coliform levels, so that contamination can be eventually mitigated. We performed a retrospective analysis of historical results of fecal coliform concentrations from 2006 to 2012 at five monitoring stations located in the study region. Results showed that Jatiúca Beach consistently presented the worst quality among the studied beaches. A field survey was conducted to identify existing point and non-point sources of pollution in the area. Monitoring in the vicinity of Jatiúca was spatially intensified. Fecal coliform concentrations were categorized according to tide range and tide stage. A storm drain located in northern Jatiúca was identified as the main point source of the contamination. However, fecal coliform concentrations at Jatiúca were high during high tides and spring tides even when this point source was inactive (no rainfall). We hypothesize that high fecal coliform levels in Jatiúca Beach may also be caused by aquifer contamination or, more likely, from tide washing of contaminated sand. Both of these hypotheses will be further investigated.