Abstract
Glyphosate is a popular herbicide used worldwide, and several studies consider it to be an environmental hazard affecting human health. The present study aimed to detect glyphosate in six different reservoirs of Paraíba do Sul and Guandu River Basins in Southeast Brazil, used for multiple purposes, including fishery activities and domestic water supply. Ion chromatography was used to analyze the water samples, as it is a fast and environmentally friendly technique to detect glyphosate. Our results revealed that, despite differences related to trophic state, season of the year or distance to urban areas, glyphosate was detected in all reservoirs and in three of them with concentrations above the limit imposed by Brazilian legislation. Among the environmental variables studied, turbidity presented the highest correlation with glyphosate concentrations. The effect of rainfall increasing turbidity in the rivers reinforces the importance of draining waters from surrounding areas that transport glyphosate into the aquatic ecosystems. The detection of the herbicide in the various systems confirms the wide use of this compound in the drainage basins of the studied reservoirs and highlights the importance of water monitoring. Further, the results reveal how urgent and important it is to explore through laboratory experiments the pathways of degradation of this herbicide in tropical and subtropical aquatic environments together with its effects on flora and fauna.
Highlights
The increasing availability of inorganic fertilizers and pesticides changed the course of world agriculture
Detection and quantification of glyphosate The analytical method of ion chromatography has the advantage of allowing the quantification of glyphosate in water through direct injection, without the need for preconcentration or derivatization, steps that involve sample manipulation render the analysis expensive and time-consuming
The ion chromatography used in this study allowed the quantification of glyphosate in the water of reservoirs, with the advantage of eliminating any prior treatment, resulting in time gain and low waste generation
Summary
The increasing availability of inorganic fertilizers and pesticides changed the course of world agriculture. Glyphosate was widely applied in Colombia to control weeds in coffee plantations (Schrübbers et al, 2014). Glyphosate (CAS number 1071-83-6) is a crystalline solid, with a water solubility of 12 g L-1 at 25°C (Okada et al, 2018). The endurance of glyphosate in water is subjected to physical, chemical and microbial characteristics of the environment (Mallat and Barcelo, 1998). Glyphosate can remain active in water ranging between 7 and 100 days depending on environmental conditions such as pH, temperature, suspended matter, cation concentration, aluminum, and iron content and microbial activity (Fouodjouo et al, 2015). Temporal variation in environmental glyphosate concentrations can directly depend on the time of application and rain events (Hanke et al, 2010)
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