Biomonitoramento de cursos d’água na região de Monte Carmelo - MG, utilizando Tradescantia

Abstract

The aquatic environments are impacted daily with diverse discharges of many diverse effluents. In this sense, the pollution of water resources and the increase of genotoxicity in this environment have been observed. The aim of the present study was to evaluate the environmental quality of water resources in Monte Carmelo – MG, through the micronucleus test in Tradescantia. The collections ocurred weekly from september 2015 to january 2017, being september for dry season and january for rainy season. Initially, the rods were excised and placed in distilled water for acclimatization. For each treatment, 15 plants were exposed for 24 hours. The control groups followed similar analysis. Subsequently, the plants were placed in distilled water for 24 hours to recover. Then, the inflorescences were fixed in Carnoy solution for 24 hours at 4 °C. The inflorescences were stored in 70% ethanol at 4 °C until analysis. Ten slides for each treatment were prepared. Cells were stained with 2% acetic carmine. The slides were examined under an optical microscope at 400x. 300 tetrads were analyzed per slide. The genotoxic changes were expressed by the number of micronuclei per 100 tetrads after statistical analysis (ANOVA, Tukey p <0,05). The physicochemical analyzes revealed that few parameters has presented values above the desirable limit. The rainfall levels were similar between the collection periods. The data for the water quality index reveal an improvement in the environmental parameters in the last years in the city under study. For the sample points, except for M1, they showed an increase in micronuclei frequency in relation to the control. However for M2, P1 and P2, the observed values are lower when compared to previous studies. Changes in municipal economic activities may have been the main cause for the reduction of genotoxicity levels at these points. The present work allows to infer that the TRAD-MCN test is sensitive even at low concentrations, for many sources of pollutants in aqueous environment. Thus, the association of the TRAD-MCN test with the traditional analyzes presents itself as an alternative and viable tool. This way, a bigger number of analyzes and the monitoring of these and the addition of new localities should be realized, seeking to clarify first, the genotoxic potential of the municipal aquatic environments, but also to highlight the main causal sources of local environmental contamination.