Avaliação da qualidade ambiental do Rio Uberabinha (MG) utilizando parâmetros físico-químicos e comunidades de macroinvertebrados bentônicos como bioindicadores

Abstract

Aquatic ecosystems worldwide are impacted by inappropriate land use and release of domestic and industrial effluents, which increase in proportion to the socio-economic activities. In order to preservation, it is necessary periodic monitoring of the quality of these ecosystems, using additional to the physico-chemical evaluation, biological monitoring, to determine the water quality measured by structural and functional alterations of the communities in ecological systems. Thus, the aim of this study was to perform an environmental diagnosis of the Uberabinha river (MG) using water s physico-chemical and microbiological parameters and benthic macroinvertebrate as indicators of environmental quality. Specifically, it was sought to evaluate the water quality from the legal point of view, through the framework into quality classes of CONAMA Resolution 357/2005, and to evaluate the environmental quality using different metrics of benthic macroinvertebrate communities and their responses to environmental disturbances. It was studied five points of the river upstream of Uberlândia (M1 to M5), five points in the urban area of Uberlândia (U1 to U5) and two points downstream of the city (J1 and J2). For physico-chemical and microbiological water analysis, collections were made in the dry season and the rainy season, and for macroinvertebrate sampling, collections were taken at the end of the dry season and at the beginning of the dry season, and then calculated metrics abundance, BMWP, Shannon-Wiener, Pielou eveness, taxa richness, percent EPT, Chironomidae and Oligochaeta. The comparison between these metrics simultaneously local and sampling periods was performed using Two Way ANOVA, and the relationship between metrics was evaluated by Principal Component Analysis (PCA). The most important standards among water s physico-chemical and microbiological parameters were determined using a principal components analysis (PCA). Most of the sampling points fell into the Class 4 of CONAMA 357, and the variables BOD, COD, turbidity, conductivity, total suspended solids, total nitrogen, ammonia nitrogen, nitrite, total phosphorus and fecal coliform showed a gradient of environmental quality, from the sampling points located upstream of Uberlândia (M1 to M5), which showed better environmental quality, to points downstream of the city (J1 and J2) and the last point of Uberlândia s urban area (U5), which had the worst water quality, due to the release of domestic sewage. With regard to metrics, sampling points upstream showed higher values of diversity, richness, BMWP and % of EPTs in relation to the urban area and downstream point. The metrics % of EPT and Shannon-Wiener s index (H\'), followed by taxonomic richness were those that best reflected the environmental quality of Uberabinha river, referring to the good quality of the points located upstream of Uberlândia, by being distant to urban area, and in the worst conditions, the point U5 and points downstream of Uberlândia, which are heavily impacted.