Environmental Quality and Cytogenotoxic Impact of the Waters of a Stream Receiving Effluents from Tannery Industry

The Estância Velha stream integrates the Sinos River Basin that provides drinking water in one of the most important Brazilian centers, the “Capital of tanneries,” and it receives effluents from tannery industries. In Brazil, water quality is monitored only through physicochemical and microbiological parameters, and considering the biomarkers’ importance in complementing the analysis, the present study was aimed at evaluating the environmental quality of the Estância Velha stream also through cytogenotoxic criteria, at the stream source (site 1), as well as upstream (site 2) and downstream (site 3) of the demographically most dense area. The results for dissolved oxygen, color, total phosphorus, silver, and thermotolerant coliforms classified the Estância Velha stream as class 4 in general; that is, the water is suitable only for navigation and to landscape harmony. Overall, the water was classified as poor by Water Quality Index (WQI) and as hypereutrophic by Trophic State Index (TSI). The main genotoxic alterations (micronuclei and nuclear buds) were observed in site 2, in which were obtained the highest levels of aluminum, silver, iron, and manganese. Despite this, most of the effluents released from the region are not treated prior to being discharged into the stream, suggesting the requirement for effluent treatment to ensure the quality of the water source available.