Análise de qualidade das águas de abastecimento público em zonas rurais e urbanas do município de Cerro Largo/RS

Abstract

Water resources are subject to degradation processes due to the release of chemical substances from domestic, industrial and agricultural production effluents, which cause changes in the physical, chemical and biological state of water, negatively impacting the quality of water for its multiple uses, especially for the noblest destination, public supply. In this sense, the aim of this study was to analyze the quality of groundwater regarding physical-chemical, microbiological and multi-residue pesticides in ten points (called P1 to P10), sampling public supply in rural and urban areas of a municipality located in the Missions Region of the state of Rio Grande do Sul. For this purpose, groundwater sampling was carried out in homes (urban area) and in supply wells (rural area) located in the city, using the criterion of choice of points, those that supply wells that served the largest population in rural and urban areas. Therefore, the water quality was evaluated considering the parameters UV absorbance λ-254 nm, electrical conductivity (μS cm-1), dissolved oxygen (OD) (mg L-1), sedimentable solids (mL L-1), and those established in Consolidation Ordinance nº 5/2017 and Ordinance nº 888/2021 of the MS, such as total coliforms (presence/absence), Escherichia coli coliforms (presence/absence), apparent color (uH), residual chlorine free (ppm), nitrate (mg L-1), hydrogenic potential (pH), temperature (°C) and turbidity (uT), and by means of High Performance Liquid Chromatography coupled to Mass Spectrometry (HPLC-MS) were determined 26 pesticide compounds, namely: atrazine, azoxystrobin, bentazone, cyproconazole, difenoconazole, clomazone, epoxiconazole, imazethapyr, imidacloprid, fipronil, malathion, pirimicarb, propiconazole, simazine, imazapique, carbofuran, tebuconazole, pyriconazole, metsulfuronmethyl, penoxlam, pyrazusulfuron-ethyl, profenophos, propanil, thiamethoxam and trifloxystrobin. The results regarding the physical-chemical parameters, except for free residual chlorine, which obtained a satisfactory result in only one sampling point (P4) located in the urban area, were in line, when relevant, with Ordinance nº 5/2017 and nº 888/2021, both from the Ministry of Health. Regarding microbiological parameters, only in P10 (rural area) the presence of E. coli was identified. Regarding the determination of pesticide compounds, atrazine was detected above the Quantification Limit of the method (LQm), in the summer season. Finally, although present, the quantified pesticide did not present values above the VMP established by Consolidation Ordinance nº 5/2017 and Ordinance nº 888/2021 of the Ministry of Health (MS).