AVALIAÇÃO DA QUALIDADE DA ÁGUA DA BACIA HIDROGRÁFICA DO RIO VERDINHO LOCALIZADO NO MUNICÍPIO DE RIO VERDE-GOIÁS

Abstract

Agricultural production increase is related to pesticides excessive use because crops require large amounts of agrochemicals. Therewith, the environmental quality is compromised contributing effectively to surface and groundwater contamination. Contamination resulting from the pesticides use occurs mainly by pesticides leaching, runoff and drainage processes, which will arrive the water streams and their watersheds. Thereby, this study objective was to monitor the water quality in rio Verdinho watershed located in Rio Verde - Goiás, standardize and validate an analytical methodology using SPE / LC-UV to determine the herbicides 2,4-D, atrazine and diuron. The water quality monitoring was carried out from January to July 2015months, at six points along rio Verdinho watershed, considering physical, chemical and microbiological parameters. The analyzed parameters were pH, temperature, turbidity, dissolved oxygen, total dissolved solids, electrical conductivity, chemical oxygen demand, nitrate, total phosphorus, total coliforms and Escherichia coli. The analytical method standardization and validation occurred through the sample preparation for solid phase extraction (SPE) and the herbicides identification was performed by high performance liquid chromatography with UV-Vis detector. Extraction parameters optimization was carried out and the method was validated by evaluating the calibration curve and linearity. Some physico-chemical and microbiological parameters did not come forward within the range permitted by CONAMA Resolution No. 357, which shows that this waterbody suffers environmental impacts mainly related to rural activities in the region. The analytical method standardization and validation results showed excellent linearity with r2 value higher than 0.9 for all analyzed herbicides. Thus, the SPE / LC-UV method allowed the 2,4-D, atrazine and Diuron herbicides extraction, concentration and identification.