ÍNDICE DE QUALIDADE DAS ÁGUAS (IQA) EM BACIAS HIDROGRÁFICAS SOB APLICAÇÃO DE VINHAÇA

Abstract

Brazil is the largest producer of sugar cane in the world, and this crop is used by the sugar energy industries to manufacture ethanol, energy and sugar, having great importance in the Brazilian economic scenario. During the alcohol distillation process, a by-product known as vinasse is produced, composed of high concentrations of nutrients, and which, when used indiscriminately, has the potential to alter soil properties in addition to allowing the contamination of water resources through its runoff and leaching. Therefore, this work aimed to evaluate changes in the water quality index of four surface water collection points located close to areas fertigated with vinasse over six years of monitoring. The study was carried out in the Alto Taquari MT region, and physical, chemical and microbiological parameters that make up the AQI calculation were evaluated, with monthly analysis totaling 288 samples. For data analysis, statistical tests were applied, making a comparison with the control analysis and subsequently evaluating the influence of the dry and rainy season. Therefore, the normality of the data was initially assessed using the Shapiro Wilks test and subsequently the Kruskal Wallis test was applied to check whether there was any influence of the years evaluated on the response variable. Finally, the Dunn test with Bonferroni correction was applied to evaluate multiple comparisons. It was found that the IQA had fluctuations over the years, remaining between regular, good or excellent. There was no influence of fertigation and the dry and rainy seasons on the monitored data, with the exception of the C21 period in relation to S20, and S20 in relation to the S21 period, making it possible to show that water quality improved over the years.