Occurrence of glyphosate and AMPA in an agricultural watershed from the southeastern region of Argentina

• Published in: The Science of the total environment Vol. 536; pp. 687 - 694
• Main Authors: Lupi, Leonardo, Miglioranza, Karina S.B., Aparicio, Virginia C., Marino, Damian, Bedmar, Francisco, Wunderlin, Daniel A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2015
• Subjects: Agricultural watershed; Agriculture; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid - analysis; AMPA; Argentina; Carbon; Contaminants; Environmental Monitoring; Glycine - analogs & derivatives; Glycine - analysis; Glyphosate; Half-Life; Herbicides - analysis; Pesticide Residues - analysis; Pesticides; Sampling; Sediments; Soil profile; Soils; Texture; Water Pollutants, Chemical - analysis; Argentina; AMPA; Agricultural watershed; Soil profile; Glyphosate
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.07.090

Glyphosate (GLY) and AMPA concentrations were determined in sandy soil profiles, during pre- and post-application events in two agricultural soybean fields (S1 and S2). Streamwater and sediment samples were also analyzed. Post-application sampling was carried out one month later from the event. Concentrations of GLY+AMPA in surface soils (0–5cm depth) during pre-application period showed values 20-fold higher (0.093–0.163μg/g d.w.) than control area (0.005μg/g d.w.). After application event soils showed markedly higher pesticide concentrations. A predominance of AMPA (80%) was observed in S1 (early application), while 34% in S2 for surface soils. GLY+AMPA concentrations decreased with depth and correlated strongly with organic carbon (r between 0.74 and 0.88, p<0.05) and pH (r between −0.81 and −0.76, p<0.001). The slight enrichment of pesticides observed from 25cm depth to deeper layer, in addition to the alkaline pH along the profile, is of high concern about groundwater contamination. Sediments from pre-application period showed relatively lower pesticide levels (0.0053–0.0263μg/g d.w.) than surface soil with a predominance of glyphosate, indicating a limited degradation. Levels of contaminants (mainly AMPA) in streamwater (ND-0.5ng/mL) denote the low persistence of these compounds. However, a direct relationship in AMPA concentration was observed between sediment and streamwater. Despite the known relatively short half-life of glyphosate in soils, GLY+AMPA occurrence is registered in almost all matrices at different sampling times (pre- and post-application events). The physicochemical characteristics (organic carbon, texture, pH) and structure of soils and sediment in addition to the time elapsed from application determined the behavior of these contaminants in the environment. As a whole, the results warn us about vertical transport trough soil profile with the possibility of reaching groundwater. [Display omitted] •The fate of GLY+AMPA was studied in agricultural soil profiles from soybean fields.•GLY+AMPA in soil profile were well correlated with organic carbon content and pH.•GLY was concentrated in the upper soil layer after application.•GLY and AMPA were detected in streamwater and sediment at lower levels than soils.