Water quality in the lotic area of the Antas river before and after the construction of the Monte Claro hydroelectric plant, south Brazil

Abstract

AIM: This study characterized the water quality of the lotic areas of the Rio das Antas (Antas River)influenced by the construction of the Monte Claro hydroelectric plant (South Brazil), a run-of-the-river reservoir. METHODS: To assess the water quality, we selected four sampling points based on the results obtained in the water-quality monitoring program performed by CERAN (the Rio das Antas Energetic Company) in the pre-filling (2002-2004) and post-filling (2005-2008) periods. The river flow was monitored during both of the periods. Seasonal samplings were conducted, and alkalinity, chlorophyll a, total and fecal coliforms, conductivity, color, BOD, COD, total phosphorus, nitrate, nitrite, ammoniacal nitrogen, dissolved oxygen, pH, total dissolved solids, suspended solids, sulfates, temperature and turbidity were evaluated. The results were interpreted according to the Brazilian Environmental Council's Water Quality Index, Trophic State Index and CONAMA Resolution 357/05. To verify the occurrence of alterations before and after the plant operation, t-tests were performed. RESULTS: Significant changes in water quality were not observed after the impoundment. The permanence of the characteristics of the natural hydrography was important for maintaining the water quality. The decline of the water quality in a stretch with reduced flow was caused by Burati stream, a tributary containing high concentrations of nutrients and fecal coliforms. CONCLUSIONS:The Monte Claro hydroelectric plant did not alter the water quality of the Antas River. The small reservoir resulting from the plant project favors the maintenance of the water quality of the river and does not favor eutrophication. Attention should be given to Burati stream, a tributary of the Antas River, regarding its high nutrient and coliform content.

Freshwater parameters in the state of Rio Grande do Sul, southern Brazil, and their influence on fish distribution and aquaculture

“…Previous analysis of water from ponds and streams from Rio Grande do Sul presented mean pHs similar to those found in the different regions of this study (Rheinheimer & Souza, 2000;Diel et al, 2007;König et al, 2008;Pimenta et al, 2012;Silva et al, 2012), but in water used for human consumption from artesian wells, from the north central region minimum pH values were down to 4.4 and the maximum up to 10.0 (Rheinheimer & Souza, 2000).…”

“…Mean alkalinity values observed in this study were in agreement with the low levels verified in previous studies (Pimenta et al, 2012;Silva et al, 2012;Kochhann et al, 2013). Alkalinity levels of 63 and 92 mg CaCO 3 L -1 did not affect fertilization and hatching rates, survival or growth of R. quelen larvae (Benaduce et al, 2008).…”

“…Low turbidity values (3-97 NTU) were also observed in other studies of rivers in this state (Petry & Schulz, 2006;Salomoni et al, 2006;König et al, 2008;Blume et al, 2010;Pimenta et al, 2012;Panizzon et al, 2013). High turbidity is associated with a lack of marginal vegetation and deforested areas that favor runoff of sediment during rainy periods (Wachholz et al, 2011;Mattos et al, 2014).…”

Qualidade da água de três locais com potenciais fontes de contaminação no Rio Taquari, RS

“…A bacia hidrográfica do sistema Taquari-Antas situa-se na região nordeste do estado do Rio Grande do Sul, abrangendo uma área de 26.428 km 2 , com aproximadamente 530 km de extensão (Pimenta et al, 2012). Essa bacia nasce no extremo leste do Planalto dos Campos Gerais e tem suas nascentes nos municípios de Cambará do Sul, Bom Jesus e São José dos Ausentes, sendo em sua parte superior denominado de Rio das Antas; e em sua parte inferior, Rio Taquari.…”