Análise de alguns parâmetros de qualidade da água na baía do Guajará em Belém-PA e os efeitos do regime pluviométrico e de marés

Abstract

Belém is located in the estuarine region, conformed by the Guajarino Estuary, which integrates the Marajoara Gulf, whose fluvial environment is formed at the confluence of the rivers Pará, Tocantins, Acará and Guamá (IPEA, 2016). The water level of the Guajarino Estuary presents fluctuations associated with the seasonal effect (seasonal variations of the rain in the hydrological basins) and the tide (variations of the tide level). The elaboration of this study is due to the fact that the seasonal variations seem to be associated to the environmental changes, that occur in the ecosystem, such as the effect of hydrological seasonality - tides and rainfall. The present study will analyze the physico-chemical components of the Guajará Bay water, relating them to the tides and the hydrological dynamics of the Guamá and Pará rivers, also in this research will be made the analysis of the role of precipitation in the alteration of the water bay physicochemical components. Initially, a descriptive statistic was made, verifying the values of the averages, of the maximum and minimum, facilitating to observe which are in agreement with the current resolution of CONAMA 357/2005. It was also applied the statistical method of Pearson correlation to evaluate the degree of relationship between variables, the correlation was first studied between physico-chemical parameters, thus, it was observed that the parameters that have a strong positive correlation were the electrical conductivity, TDS and salinitiy. The other parameters did not presented significative correlation, demonstrating that they were independent of each other. When applying the correlation between the physical-chemical parameters and the rainfall, no positive or negative correlation was found between these variables, meaning that the role of the rainfall city of Belém, was not mostly important in the variation of the physico-chemical components of the bay and this was also the case for the relationship between the parameters and the tide heights. The behavior graphs of the physical-chemical parameters, in relation to rainfall, showed that among the nine parameters analyzed, six parameters were altered, such as: pH, temperature, electrical conductivity, TDS, salinity, OD and Turbidity. These parameters have changed due to precipitation. The results of the parameters regardind the tides were observed among the nine parameters studied, decreasing the temperature, and increasing the values of electrical conductivity, TDS, salinity and turbidity.