EGU2017-1993 Can an aquatic macrophyte bioaccumulate glyphosate? A watershed scale study using a non-target hydrophyte Ludwigia peploides

PÉREZ, DÉBORA JESABEL; OKADA, ELENA; MENONE, MIRTA LUJÁN; APARICIO, VIRGINIA; COSTA, JOSE LUIS

Viena

Congreso; European Geosciences Union General Assembly 2017. Session SSS7.8/BG9.10/HS11.53 The impact of pesticides in life, water, sediment, air and soil resources; 2017

The hydrophyte Ludwigia peploides is widely distributed in South America streams, and therefore, it can be used as a biomonitor for pesticides used in agricultural production. Glyphosate is one of the main pesticides used in Argentina. This has resulted in its occurrence in non-target wetland ecosystems. The objectives of this study were to: 1) establish and validate an extraction and quantification methodology for glyphosate in L.peploides plants, and 2) evaluated the role of this species as a glyphosate biomonitor in the agricultural watershed of the El Crespo stream. For the first objective, we collected plant material in the field. The leaves were dissected and oven dried at 60º C, grinded and sieved through a 0.5 mm mesh. Different solutions were tested for the extraction step. Labeled glyphosate was used as an internal standard to evaluate the recovery rate and the matrix effect of the different extraction methods. Glyphosate was derivatized with FMOC-Cl and then quantified by ultra-performance liquid chromatography (UPLC) coupled to a mass tandem spectrometer (MS/MS). The method based on an aqueous phase extraction step 0.01 mg/mL of activated carbon as a clean-up to decrease the matrix interference had a recovery of 117 ± 20% and the matrix effect was less than 20%. This method was used to analyze the glyphosate levels in L.peploides in the El Crespo stream. For the second objective, plants of L.peploides were collected on March 2016 in eight monitoring sites of the stream from the headwaters to the stream mouth. Surface water and sediments samples were collected at the same time to calculate the bioconcentration factors (BCFs) and biota-sediment bioaccumulation factors (BSAFs). The BCFs ranged between 28.57 - 280 L/Kg and the BSAFs ranged between 2.52- 30.66 at different sites. These results indicate that L.peploides can bioaccumulated glyphosate in its leaves and the major bioavailability is given mainly by the herbicide molecules present in surface water, rather than sediment. In this sense, L.peploides could be used as biomonitor organism to evaluate a glyphosate levels in the freshwater aquatic ecosystems.