Determinação multirresíduos de agrotóxicos em águas de poços de captação utilizados para o consumo humano na zona rural de Cerro Largo (RS)

Abstract

Nowadays, several researchers have been warning about the problems caused by the use of agrochemicals in Brazil and worldwide. However, the usage of these compounds are increasing in order to control the integrity of plantations. In this context, the objective of this work is to evaluate the presence of pesticides by liquid chromatography coupled to mass spectrometry in rural water supply wells in Cerro Largo state of Rio Grande do Sul. Samples from twelve artesian wells were analyzed and the water quality was evaluated by considering the following physical-chemical parameters: absorbance (λ - 254 nm), electrical conductivity (mg L-1), apparent color (uH), dissolved oxygen (mg L-1), pH, sedimentable solids (mg L-1), temperature (°C) and turbidity (uT). The results obtained were compared to a regulatory system, Portaria da Consolidação (PRC) No 5/2017 in Ministry of Health (MS). Four collections were carried out, one in each season of the year, the physical-chemical parameters were analyzed followed by analysis in two detection wells and quantification of the presence of pesticides. The agrochemicals monitored in water samples using CLAF-EM were: Atrazine, Azoxystrobin, Cyproconazole, Clomazone, Diphenoconazole, Epoxiconazole, Fipronil, Imazapyr, Malathion, Metsulfuron-methyl, Penoxsulam, Pyraclostrobin, Pirimicarb, Profenofos, Propanil, Propiconazole, Simazine and Tiabendazole. Concentrations varied between 0.013 to 8.864 μg L-1. The agrochemicals detected in well 1 in summer season were: Azoxystrobin (0.030 μg L-1), Fipronil (0.211 μg L-1), Metsulfuron-methyl (0.374 μg L- 1), Penoxsulam (1.729 μg L-1), Profenofos ( 1.958 μg L-1) and Propanil (8.864 μg L-1); in fall season: Atrazine (0.040 μg L-1), Azoxystrobin (0.396 μg L-1), Penoxsulam (0.648 μg L-1) and Propanil (0.881 μg L-1); in winter season: Metsulfuron-methyl (0.557 μg L-1) and Propanil (1.602 μg L-1); and in spring season: Atrazine (0.050 μg L-1), Azoxystrobin (0.170 μg L- 1), Fipronil (0.085 μg L- 1), Penoxsulam (0.866 μg L-1) and Propanil (0.679 μg L-1). The substances found in well 2 during summer were: Cyproconazole (0.110 μg L-1), Epoxiconazole (0.006 μg L-1), Malathion (0.649 μg L- 1), Penoxsulam (0.374 μg L-1) and Pyraclostrobin (0.157 μg L-1); in fall season: Atrazine (0.031 μg L-1), Azoxystrobin (0.143 μg L-1), Fipronil (0.085 μg L-1), Metsulfuron-methyl (0.150 μg L-1) and Penoxsulam (0.063 μg L-1); in winter: Atrazine (0.015 μg L-1), Azoxystrobin (0.068 μg L- 1), Fipronil (0.085 μg L-1), Imazapyr (0.027 μg L-1) and Penoxsulam (0.063 μg L-1); and in spring: Azoxystrobin (0.170 μg L-1), Diphenoconazole (0.029 μg L-1), Fipronil (0.085 μg L- 1) and Penoxsulam (1.231 μg L-1). Even though detected, the quantities of agrochemicals did not surpassed the regulatory system stablished in PRC N° 5/2017.