Caracterização hidroquímica e avaliação do potencial de contaminação por pesticidas em águas subterrâneas do município de Candelária

Abstract

The present study aims to characterize groundwater physicochemical parameters in the municipality of Candelária, correlating the existence of species with geological and/or anthropological causes, in addition to assessing the local vulnerability and potential risk of contamination of pesticides most used in the various crops of the region. The study was developed from the collection and analysis of 26 samples from wells located in the rural area, in two different times. The hydrochemical characterization was performed through the interpretation of Piper and Stiff diagrams and the distribution of results in thematic maps. Results were compared to the maximum contaminant levels (MCL) by Consolidation Ordinance No. 005/2017 and CONAMA Resolution 396/2008. To assess the potential for contamination of pesticides used in the region, the EPA screening criteria, the GUS index and the GOSS method were applied. The presence of glyphosate, imazethapyr and 2,4-dichlorophenoxyacetic acid herbicides was investigated in the collected samples. Results indicated a predominance of sodium bicarbonate waters, divided into two groups, one with higher Na+ and K+ concentrations, indicating water Ca-HCO3 to Na-HCO3 evolution and a second group with fewer dissolved species, indicating rapid circulation and short residence time. Concentrations above MCL were found for 11 wells in at least one of the collections. The presence of the investigated herbicides in the samples was not detected. The vulnerability in the 4 evaluated points varied from low to high. From the distribution of the analysis of the main parameters, it was possible to determine the predominant characteristics of groundwater in each outcrop area investigated.