Dale R Van Stempvoort1, John Spoelstra1,2, Natalie D Senger2, Susan J Brown1, Ryan Post3, John Struger1. 1. Environment Canada - Water Science and Technology Directorate, Burlington, ON, Canada. 2. Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada. 3. Engineering and Technical Services, Nottawasaga Valley Conservation Authority, Utopia, ON, Canada.
Abstract
BACKGROUND: The objective of this study was to investigate the occurrence of glyphosate residues (glyphosate and its metabolite AMPA) in shallow groundwater in a catchment dominated by agriculture, and to examine the potential for this groundwater to store and transmit these compounds to surface waters. RESULTS: Glyphosate residues were found in some of the groundwater samples collected in riparian (surface seeps), upland (mostly <20 m below ground) and wetland settings (<3 m below ground). Overall, glyphosate and AMPA were detected in 10.5 and 5.0%, respectively, of the groundwater samples analyzed as part of this study. All concentrations of glyphosate were well below Canadian guidelines for drinking water quality and for protection of aquatic life. Seasonal differences in concentrations in riparian seeps were possibly related to cycles of weather, herbicide application and degradation of glyphosate. Highest concentrations were at upland sites (663 ng L(-1) of glyphosate, 698 ng L(-1) of AMPA), apparently related to localized applications. Most glyphosate detections in wetlands were >0.5 km distant from possible areas of application, and, combined with other factors, suggest an atmospheric transport and deposition delivery mechanism. In both upland and wetland settings, highest glyphosate concentrations were sometimes not at the shallowest depths, indicating influence of hydrological factors. CONCLUSION: The glyphosate/AMPA detections in riparian seeps demonstrated that these compounds are persistent enough to allow groundwater to store and transmit glyphosate residues to surface waters. Detections in the wetlands support earlier evidence that atmospheric transport and deposition may lead to glyphosate contamination of environments not intended as targets of applications. This interpretation is further supported by detections of both glyphosate and AMPA in precipitation samples collected in the same watershed.
BACKGROUND: The objective of this study was to investigate the occurrence of glyphosate residues (glyphosate and its metabolite AMPA) in shallow groundwater in a catchment dominated by agriculture, and to examine the potential for this groundwater to store and transmit these compounds to surface waters. RESULTS:Glyphosate residues were found in some of the groundwater samples collected in riparian (surface seeps), upland (mostly <20 m below ground) and wetland settings (<3 m below ground). Overall, glyphosate and AMPA were detected in 10.5 and 5.0%, respectively, of the groundwater samples analyzed as part of this study. All concentrations of glyphosate were well below Canadian guidelines for drinking water quality and for protection of aquatic life. Seasonal differences in concentrations in riparian seeps were possibly related to cycles of weather, herbicide application and degradation of glyphosate. Highest concentrations were at upland sites (663 ng L(-1) of glyphosate, 698 ng L(-1) of AMPA), apparently related to localized applications. Most glyphosate detections in wetlands were >0.5 km distant from possible areas of application, and, combined with other factors, suggest an atmospheric transport and deposition delivery mechanism. In both upland and wetland settings, highest glyphosate concentrations were sometimes not at the shallowest depths, indicating influence of hydrological factors. CONCLUSION: The glyphosate/AMPA detections in riparian seeps demonstrated that these compounds are persistent enough to allow groundwater to store and transmit glyphosate residues to surface waters. Detections in the wetlands support earlier evidence that atmospheric transport and deposition may lead to glyphosate contamination of environments not intended as targets of applications. This interpretation is further supported by detections of both glyphosate and AMPA in precipitation samples collected in the same watershed.
Authors: Luã Reis; Marilena Raciti; Patricia González Rodriguez; Bertrand Joseph; Ibrahim Al Rayyes; Per Uhlén; Anna Falk; Suzana Telles da Cunha Lima; Sandra Ceccatelli Journal: Environ Toxicol Date: 2022-04-29 Impact factor: 4.109
Authors: Eduardo C Reynoso; Ricardo D Peña; Delfino Reyes; Yaselda Chavarin-Pineda; Ilaria Palchetti; Eduardo Torres Journal: Int J Environ Res Public Health Date: 2020-09-28 Impact factor: 3.390