AVALIAÇÃO DA QUALIDADE DA ÁGUA DO CÓRREGO VACA BRAVA, GOIÂNIA – GOIÁS: CONTRIBUIÇÕES PARA CIÊNCIAS AMBIENTAIS E SAÚDE

Abstract

The process of land occupation in Goiânia demonstrates that, Owing to its accelerated populational growth, the city reproduced all the socioenvironmental contradictions of a big metropolis. In this context the Vaca Brava Stream is patially inserted in the Vaca Brava Municipal Park (VBMP), which possess na important environmental role. This study reports na evaluation of the physical, chemical and microbiological characteristics of the Vaca Brava Stream, with a temporal and spatial analyses of its limnological characteristics. The samples collecting was carried out in eight points along the longitudinal axis of the Vaca Brava Stream between June 2015 and May 2016, encompassing the rainy and dry seasons. Twenty-seven physical-chemical and biological parameters were monitored being that, in the field the values of eight were obtained with the remaining 19 measured in a laboratory. For the results a principal component analysis (PCA) was performed, with the t-test to verify differences between the collecting periods (dry and rainy). In a general manner, the results indicated waters with low values of turbidity, nutrients, DBO5 and Chlorophyll-a. However, there were exceptions, as the high concentrations of total phosphor, orthophosphate, total nitrogen (Kjeldahl), and amoniacal nitrogen, recorded in some places during the dry season. Low concentrations of dissolved oxygen were also frequente in the study area. The results point to na expected seasonality which may be related to a larger contribution of poluting sources. The protection of the Vaca Brava Stream headwaters contribute to better values in the sampling points located upstream, most probably owing to the fact of the VBMP. The disordely human occupation is reflected in the higher housing concentration (especially vertical) in the intermediar parts of the Vaca Brava Stream, being coherent with the more negative results expressed in this stretch of the stream. Among all sampling points, the most relevant for the majority of alterations is the Point 5, which might be reflecting the efluente loads coming from sewers, commerce, and small industries as channeled form or surface runoff in the rainy seasoin.