Teores de íons metálicos no rio São Francisco verdadeiro e tributários

Abstract

Eleven counties in the Western Paraná take part of São Francisco Verdadeiro River Basin, whose headspring is in the urban area of Cascavel City. Thus, the importance of monitoring its water quality came to light. In order to evaluate it, ten collection points were selected, so that physical and chemical water parameters such as flow rate, pH, temperature, total organic carbon, organic carbon, electrical conductivity and concentrations of Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni and Zn were evaluated fortnightly from August 1st, 2012 to July 17th, 2013, totalizing 26 samples for each researched site. The water samplings were stored in an amber glass bottle with 2.5-liter capacity, U.S. DH - 48 sampler model and stem. The samples preparation was carried out according to the procedure described by NBR 13809:1997. In the laboratory, after the digestion step, the extracts were submitted to multi-elemental analysis to determine the metal contents by atomic absorption spectrophotometer, with wavelengths and specific calibration curves. The results were graphically analyzed by boxplot according to the collection points, to enable the observation of variation range and extreme values presence. Therefore, line graphs were drawn to analyze the element concentrations distribution over time. The results were compared to the limits established by CONAMA 357/2005 Resolution. Thus, in order to record water quality at the collection points, according to land use, it was carried out the analysis of the most important components. Lastly, it is concluded that the Cr concentration in point S01, Cu and Mn concentrations in agricultural regions and Ni and Zn concentrations in agricultural and urban areas are above the levels prescribed by CONAMA 357/2005 Resolution. These data have indicated that there are some basin environmental impacts in the agricultural and urban areas.